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Rice Science, 2021, 28(5): 479−492

Research Paper

Breeding Novel Short Grain for Tropical Region to Combine Important Agronomical Traits, Biotic Stress Resistance and Cooking Quality in Background

1 1 1 1 Uthomphon SAICHOMPOO , Possawat NARUMOL , Pawat NAKWILAI , Peeranut THONGYOS , 2 2 3 4 Aekchupong NANTA , Patompong TIPPUNYA , Siriphat RUENGPHAYAK , Teerarat ITTHISOPONKUL , 5 6 1 Niranee BUERAHENG , Sulaiman CHEABU , Chanate MALUMPONG (1Department of Agronomy, Faculty of Agriculture at Kamphaeng Saen, Kasetsart University, Nakhon Pathom 73140, ; 2Tana Group International Co., Ltd., Phan, 57120, Thailand; 3Rice Science Center & Rice Gene Discovery Unit, Kasetsart University, Kamphaeng Sean Campus, Nakhon Pathom 73140, Thailand; 4Faculty of Agricultural Product Innovation and Technology, Srinakharinwirot University, Bangkok 10110, Thailand; 5Faculty of Science Technology and Agriculture, Yala Rajabhat University, , Yala 95000, Thailand; 6Faculty of Agriculture, Princess of Naradhiwas University, Narathiwat 96000, Thailand)

Abstract: Breeding program strategies to develop novel short grain varieties such as japonica (short grain) that introgress biotic stress resistance and high grain quality have been developed using indica rice (Pin Kaset+4 and Riceberry) for applications in (Koshihikari) improvement. Four breeding lines showing promising agronomic performance with short grain and low amylose content (< 20%) were obtained. In addition, sensory testing of these breeding lines showed high scores that similar to Koshihikari. Two promising lines, KP48-1-5 and KP48-1-9, which possessed a combination of four genes resistance to different biotic stresses (Bph3 + TPS + Xa21 + Pi-ta) and four genes for grain quality (GS3 + SSIIa + wxb + badh2), were developed using marker-assisted selection (MAS) with the pedigree method. The current study clearly illustrated the successful use of MAS in combining resistance to multiple biotic stresses while maintaining a high yield potential and preferred grain quality. Moreover, the results indicated that this breeding program, which includes crossing temperate japonica with indica, can create novel short grain rice varieties adapted to a tropical environment, like the japonica type. Key words: marker-assisted breeding; short grain rice; grain quality; biotic resistance

The popularity of Japanese food and the increase in resulting in a high price for this commodity (Kang, the Japanese population in Thailand have recently 2010). Therefore, the japonica rice used for cultivation increased the demand for japonica rice. In fact, under tropical conditions should be improved. restaurant chains from Japan have increasingly Chiang Rai, the northernmost province in Thailand, invested in Thailand to open Japanese restaurants at a has become a major production base for japonica rice growth rate of 10%‒15% per year. As a result, because of its climate, and locally developed accessions Thailand ranks the fifth in the world in terms of its of japonica varieties have qualities similar to those of number of Japanese restaurants (Miyamoto, 2017). accessions grown in Japan (Warinrak, 2013). In 1995, However, the production of temperate japonica rice in there were two known japonica rice varieties [DOA1 tropical region such as Thailand is very limited, from (SN) and DOA2 from Akitakomachi

Received: 10 August 2020; Accepted: 26 October 2020 Corresponding author: Chanate MALUMPONG ([email protected]) Copyright © 2021, China National Rice Research Institute. Hosting by Elsevier B V This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) Peer review under responsibility of China National Rice Research Institute http://dx.doi.org/10.1016/j.rsci.2021.07.008

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(AK)] that are suitable for planting in the northern backcross methods with marker-assisted selection parts of Thailand because their resistance to hot (MAS) were used to select rice varieties for short weather is higher than other japonica rice varieties grain, high yield, good cooking quality and resistance (Seemanon et al, 2015). However, DOA1 and DOA2 to biotic stress. off-type plants were found in the fields, and the genetic background of the two varieties was changed RESULTS compared with the original SN and AK from Japan Weather data during breeding program (Nakwilai et al, 2020). Therefore, after 25 years, DOA1 and DOA2 were incompletely integrated into The weather data during the five years of the breeding the genetic backgrounds of SN and AK, respectively. program is shown in Fig. S1. The mean daytime and Thus, a japonica rice breeding program should be nighttime temperatures for the five years were 26.7 ºC started in Thailand to breed new varieties for and 23.0 ºC , and the mean maximum and minimum alternative choices in japonica rice production. temperatures for the five years were 31.2 ºC and 20.2 ºC , In Japan, the best japonica cultivar is ‘Koshihikari’ respectively. In addition, the mean relative humidities (KH), which was grown on 36.2% of the total rice during the daytime and nighttime over the five years area in 2016, and since then, it has continuously were 72.1% and 88.2%, respectively, and the average maintained its top position in Japan because of its high rainfall over the five years was 4.1 mm. eating quality and appeal to Japanese consumers Breeding program during early generations (Kobayashi et al, 2018). Thus, it has been used as a genetic resource to improve eating quality in rice The results of the breeding program are shown in Fig. breeding throughout Japan (Wada et al, 2013). 1. In the first cross, the paddy grain shapes of the two However, KH is less resistant to lodging and more parents KH (width/length 3.80/6.90 mm) and RB susceptible to diseases such as blast than other (width/length 2.60/11.20 mm) were identified as the varieties. In addition, it is slight resistance to bacterial shortest and longest grain phenotypes, respectively, leaf blight (Ishizaka et al, 1989). whereas the paddy grain shapes of their progenies in The new Thai indica variety ‘Pin Kaset+4’ (PinK4) BC1F1 ranged from 2.50‒3.70 mm in grain width and was improved by the pseudobackcrossing method for 7.00‒11.00 mm in grain length (data not shown). The pyramiding multiple traits. PinK4 is introgressed with paddy grain shapes of the F2 progenies ranged from six target genes and three QTLs, including those for 2.60‒3.90 mm in grain width and 6.60‒11.00 mm in resistance to bacterial leaf blight (BLB; xa5 and Xa21), grain length (Fig. 2-A and -B). Thus, 52 short grain leaf-neck blast (BL; Pi-ta), brown planthopper (BPH; plants of BC1F1 and 45 plants of F2 were selected and qBph3, qBL1, qBL11 and TPS) and flash flooding continued to BC1F3 and F4 generations, respectively. (Sub; Sub1A and Sub1C). In addition, it is characterized In the second cross, KH × PinK4, the paddy grain as high yield and aromatic qualities (badh2) and exhibits shapes of the F2 progenies ranged from 2.61‒3.80 mm improved starch profiles (soluble starch synthase IIa; in width and 6.60‒10.00 mm in length. For the SSIIa) (Ruengphayak et al, 2015). Another Thai indica parental lines, KH displayed a short grain (width/ variety ‘Riceberry’ (RB), a new variety, was length 3.39/7.30 mm), while PinK4 had a long grain developed using conventional breeding between Hom (width/length 2.85/10.70 mm) (Fig. 2-C and -D). Thus, Nin, a local non-glutinous purple rice, and Khoa 27 F2 plants were selected and continued to F4 Dawk Mali 105, a premium fragrant rice, and then generation. selected by the pedigree method. RB becomes soft, fluffy and fragrant when cooked (Poosri et al, 2019). Advancement of generations Thus, these Thai indica varieties were used as parents Phylogenetic relationships of selected lines in this research. Therefore, breeding program strategies that are For BC1F4 and F5 from KH × RB, five and one lines successful in developing novel short grain white rice were selected, respectively. Notably, seven lines were varieties such as japonica (short grain) have been selected from KH × PinK4. Thus, a total of 13 selected developed to support the Japanese food industry by lines from both crosses were analyzed for their genetic employing indica rice (PinK4 and RB) for application backgrounds together with their parents and control in japonica rice (KH) improvement. Pedigree and varieties (DOA1, DOA2, AK and PTT1).

Uthomphon SAICHOMPOO, et al. Breeding Short Grain Rice in Koshihikari Background 481

Fig. 1. Scheme of breeding programs for short grain rice derived from Koshihikari × Riceberry and Koshihikari × Pin Kaset+4 from WS15 to WS19 in , , Thailand. WS, Wet season; DS, Dry season; MAS, Marker-assisted selection; GBS, Genotype by sequencing.

The phylogenetic tree was divided into two groups line namely Ped (2-12-17) was classified into the (Fig. 3). Group I contained 12 selected lines together indica group. Thus, this line was discarded and the with KH, AK, DOA1 and DOA2. This group was remaining 12 selected lines were evaluated during a clearly identified as a japonica type. When considering preliminary yield trial. the selected lines, KP48-1-5 and KP48-2-4 had close Preliminary yield trial relationships to KH and DOA2, whereas BC1F4 (95-2-14) was close to AK and DOA1. Group II The preliminary yields of 12 selected lines were contained indica parental lines (RB and PinK4) and evaluated in wet season in 2018 (WS18) at Tana Grain the control indica rice, PTT1. However, the selected Polish, Ltd., Phan district, Chiang Rai Province,

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Fig. 3. Phylogenetic tree of breeding lines and control varieties based on genotyping by sequencing. The phylogenetic tree revealed two groups. Group I comprises the japonica type, while group II is made up of the indica type. The numbers at the node indicate the percentage obtained with 1000 bootstraps. Fig. 2. F2 segregations of paddy grain length and width from Koshihikari (KH) × Riceberry (RB) (A and B) and KH × Pin Kaset+4 (PinK4) (C and D). Overall sensory scores were combined from the evaluation of nine characteristics (Fig. 4-A). The overall Thailand. The grain yield (GY) and agronomic traits scores were significantly different among lines/ were significantly different among the lines/varieties varieties. KP48-1-5 (32.91) and BC95-2-14 (30.27) (P < 0.05) (Table 1). The days to 100% flowering (DF) had the highest overall scores, while the overall scores of the 12 lines were not significantly different of the control varieties (DOA2 and KH) were 28.73 compared to DOA1 and DOA2, but were significantly and 29.16, respectively. longer than those of AK and KH. The 1000-grain Considering all traits, including GY, agronomic traits, weights of the lines were significantly lower than grain quality and sensory score, and by MAS, five those of DOA1 and DOA2 except for KP48-1-5 and lines KP48-1-5, KP48-1-9, BC95-2-14, BC95-2-12 KP48-1-3. However, the GYs of the other 10 lines and BC95-2-7 were selected for continued yield trials excepted BC69-3-1 and BC90-2-4 were significantly in dry season in 2019 (DS19) and wet season in 2019 higher than those of AK and KH, and showed similar (WS19). Finally, the sensory test in WS19 revealed to those of DOA1 and DOA2. that the highest overall scores were found in When considering the grain quality, the grain BC95-2-12 and KP48-1-9, and the second highest length to width ratios were significantly different overall scores were found in KP48-1-5 and BC95-2-14 among lines/varieties (P < 0.05) (Table 2), and the (Fig. 4-B). length to width ratios of milled grains were below 2.0 for all the 12 lines. This indicated that all the lines can Validation of promising lines be identified as short grain rice. The amylose contents Evaluation of BPH, BLB and blast resistance (AC) of KP65-1-2 (23.49%) and KP48-2-4 (24.42%) were the highest when compared with other In 2019, the yield trial experiment was conducted in lines/varieties identified as hard rice. The AC of the dry season (DS19) (F6 and BC1F5) and wet season other 10 lines was less than 20%, and AK (15.79%) (WS19) (F7 and BC1F6). MAS was used to detect the and KH (15.23%) had the lowest AC (Table 2). target genes/QTLs and indicated that KP48-1-5 and KP65-1-2, KP48-2-4 and KP65-2-4 were identified as KP-1-9 were successfully fixed in terms of the having intermediate-high gelatinization temperatures, homozygosity of the eight target genes (GS3, wxb, while the other lines had high gelatinization SSIIa, badh2, Bph3, TPS, Xa21 and Pi-ta), while temperatures, similar to those of AK, KH, DOA1 and BC95-2-12, BC95-2-14 and BC95-2-7 had homozygosity DOA2 (Table 2). in the four target genes (GS3, wxb, Xa21 and Pi-ta)

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Fig. 4. Sensory test in BC1F5 derived from Koshihikari × Riceberry and F6 derived from Koshihikari × Pin Kaset+4 in wet season in 2018 (A) and candidate lines in BC1F6 and F7 in wet season in 2019 (B). Different lowercase letters follow the numbers above the column indicate significant differences among the lines at the 0.05 level using the LSD method.

(Table 3). candidate lines and KH, which contain the Xa21 gene, In WS19, the five candidate lines were screened for were classified as moderately resistant to SK1-2 and their reactions to BPH resistance. Surprisingly, the XON2-1 strains, and susceptible to NP3-5, XORE1-1 phenotyping of KP48-1-5 and KP48-1-9, which have and CR2-4 strains. In addition, KP48-1-5 and KP48-1-9 Bph3 and TPS genes, showed moderate resistance in all were classified as moderately resistant to CN1-3 strain, three biotypes, while PinK4, which contains the same while BC95-2-12, BC95-2-14, BC95-2-7 and KH were genes, was scored as resistant (Fig. 5-A). This might classified as moderately susceptible (Fig. 5-B). be because PinK4 possesses another gene, Bph32, Pi-ta gene resistance to blast disease was detected which was not screened during the MAS procedure. in every candidate line because their parents (RB, The screening of BLB found that all the five PinK4 and KH) have already possessed this gene. The

Table 3. SNP/InDel marker information on breeding lines identified in wet seasons of 2018 (WS18) and 2019 (WS19). GS3 wxb SSIIa badh2 Bph3 Line/Variety WS18 WS19 WS18 WS19 WS18 WS19 WS18 WS19 WS18 WS19 BC95-2-12 +/+ +/+ +/+ +/+ -/- -/- -/- -/- -/- -/- BC95-2-14 +/+ +/+ +/+ +/+ -/- -/- -/- -/- -/- -/- BC95-2-7 +/+ +/+ +/+ +/+ -/- -/- -/- -/- -/- -/- KP48-1-5 +/+ +/+ +/+ +/+ +/+ +/+ +/+ +/+ +/+ +/+ KP48-1-9 +/+ +/+ +/+ +/+ +/+ +/+ +/+ +/+ +/+ +/+ DOA1 +/+ +/+ +/+ +/+ +/+ +/+ -/- -/- -/- -/- DOA2 +/+ +/+ +/+ +/+ +/+ +/+ -/- -/- -/- -/- Koshihikari (KH) +/+ +/+ +/+ +/+ +/+ +/+ -/- -/- -/- -/- Riceberry (RB) -/- -/- +/+ +/+ -/- -/- -/- -/- -/- -/- Pin Kaset+4 (PinK4) -/- -/- -/- -/- -/- -/- +/+ +/+ +/+ +/+ TPS xa5 Xa21 Pi-ta Sub1c Line/Variety WS18 WS19 WS18 WS19 WS18 WS19 WS18 WS19 WS18 WS19 BC95-2-12 -/- -/- -/- -/- +/- +/+ +/+ +/+ -/- -/- BC95-2-14 -/- -/- -/- -/- +/- +/+ +/+ +/+ -/- -/- BC95-2-7 -/- -/- -/- -/- +/+ +/+ +/+ +/+ -/- -/- KP48-1-5 +/+ +/+ -/- -/- +/+ +/+ +/+ +/+ -/- -/- KP48-1-9 +/+ +/+ -/- -/- +/+ +/+ +/+ +/+ -/- -/- DOA1 -/- -/- -/- -/- +/+ +/+ +/+ +/+ -/- -/- DOA2 -/- -/- -/- -/- +/+ +/+ +/+ +/+ -/- -/- Koshihikari (KH) -/- -/- -/- -/- +/+ +/+ +/+ +/+ -/- -/- Riceberry (RB) -/- -/- -/- -/- -/- -/- +/+ +/+ -/- -/- Pin Kaset+4 (PinK4) +/+ +/+ +/+ +/+ +/+ +/+ +/+ +/+ +/+ +/+ ‘+’, Desirable allele; ‘-’, Uundesirable allele; ‘+/+’ or ‘-/-’, Homozygous; ‘+/-’, Heterozygous. Blue color marks homozygosity in the target genes.

Uthomphon SAICHOMPOO, et al. Breeding Short Grain Rice in Koshihikari Background 485

check (Jao Hom Nin, JHN) were moderately resistant to resistant against blast. However, the parent varieties were resistant to most of the seven mixed groups, except PinK4, which was susceptible to mixed group 1 and moderately resistant to mixed group 5, while RB was moderately resistant to mixed group 5 (Fig. 5-C). Evaluation of agronomic traits and grain yield The five candidate lines of the advanced progeny (in DS19 and WS19) exhibited non-significant GYs, but the agronomic traits among lines/varieties were significant (P < 0.05), as shown in Table 1. In addition, the five candidate lines in the two yield trials were also compared with those in the preliminary yield trial in WS18. DFs in WS18 and WS19 were earlier than those in DS19 in all the lines/varieties. However, the GYs in WS18 and WS19 were higher than those in DS19. In addition, the other agronomic traits varied among the lines and seasons. GYs of the five candidate lines in DS19 and WS19 were not significant from those of DOA1 and DOA2, but were significant from those of AK and KH in WS19 (Table 1). In addition, the genotype and genotype- by-environment (GGE) biplot of GY stability was analyzed (Fig. 6-A). The relationship between the mean GY and PC1 indicated that KP48-1-5 had the highest stability, followed by BC95-2-14 with the highest GY. The second highest average GY was observed for KP48-1-9, but it had low stability. Notably, the control varieties AK and KH had good stability relative to DOA1 and DOA2. In addition, the stability of these varieties was lower than that for KP48-1-5 and BC95-2-14. The biplot graph between PC1 and PC2 of GY in Fig. 6-B showed that KP48-1-5 was also highly stable, followed by BC95-2-14, KP48-1-9 and BC95-2-7 during all the three seasons. Fig. 5. Evaluation of candidate lines for brown planthopper (BPH), bacterial leaf blight (BLB) and blast resistance during wet season Evaluation of cooking quality and sensory test in 2019. A, Resistance of candidate lines, parents and control varieties against In WS19, physicochemical and cooking quality traits three biotypes of BPH. KPP, TPY and SBR refer to BPH populations of of the candidate lines and control varieties were Kamphaeng Phet, Ta Phaya and Sing Buri, respectively. analyzed (Table 4). The rice flour from RB and B, Resistance of candidate lines, parents and control varieties against six strains of BLB. KP48-1-5 had the highest contents compared C, Resistance of candidate lines, parents and control varieties against to the other lines/varieties. The cooking times (CT) of seven mixed strain groups of the blast. different lines and control varieties ranged from SES, Standard evaluation system. Data are Mean ± SD (n = 30). 10.5‒23.0 min. RB and BC95-2-14 had the highest CT. The pasting properties of the candidate lines and blast disease screening of seven mixed groups control varieties displayed no systematic trend. The indicated that all the candidate lines and a resistant textural properties in terms of hardness and stickiness,

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Fig. 6. Biplot graphs of grain yield and grain quality of five candidate lines and their control varieties. A, Biplot graph of the PC1 score versus the mean grain yield of five candidate lines and the control varieties in WS18, DS19 and WS19. B, Biplot graph of the PC1 score versus the PC2 score for the grain yields of five candidate lines and the control varieties in WS18, DS19 and WS19. C, Biplot graph of the PC1 score versus the PC2 score for the grain quality of five candidate lines and the control varieties. AC, Amylose content; SB, Setback; CPV, Cold paste viscosity; HPV, Hot paste viscosity; PV, Peak viscosity; BD, Breakdown; PC, Protein content. WS18, DS19 and WS19 refer to wet season in 2018, dry season in 2019 and wet season in 2019, respectively. which were measured using the texture profile analysis stickiness than BC95-2-7. of cooked rice displayed significant differences among The correlation coefficients (r) of the factors for all rice varieties. the rice samples are presented in Table 5. The results The hardness is negatively correlated with the showed that the parameters including peak viscosity stickiness of cooked rice (Tao et al, 2020). In this (PV), breakdown (BD), hot paste viscosity (HPV), study, both BC95-2-7 and KP48-1-5 presented the cold paste viscosity (CPV), setback (SB) and AC highest hardness values, while KP48-1-5 had lower played important roles and had positive relationships

Table 4. Physicochemical and cooking qualities of candidate lines compared with their parents and commercial varieties in wet season in 2019. Protein Cooking Viscosity (RVU) (Mean ± SD) Cooked rice texture Line/ content time Hot paste Cool paste Hardness Stickiness Variety Peak viscosity Breakdown Setback (%) (min) viscosity viscosity (N) (N∙s) BC95-2-12 6.88 b 13.0 b 216.96 ± 6.66 b 120.21 ± 4.65 c 96.75 ± 2.01 a 191.88 ± 5.95 e 71.67 ± 1.29 d 32.06 bc 19.30 bcd BC95-2-14 6.26 b 22.5 a 209.50 ± 1.88 b 115.96 ± 1.47 c 93.55 ± 3.36 ab 202.21 ± 1.24 de 86.25 ± 0.24 ab 23.76 c 20.99 bc BC95-2-7 5.43 b 11.5 b 137.08 ± 7.66 c 89.79 ± 2.77 d 47.29 ± 4.89 d 163.83 ± 4.36 f 74.04 ± 1.59 d 45.50 ab 21.91 bc KP48-1-5 8.51 a 14.0 b 204.55 ± 2.65 b 159.75 ± 0.11 b 44.79 ± 2.53 de 250.71 ± 1.94 b 90.96 ± 1.82 a 47.39 a 6.44 cd KP48-1-9 6.48 b 10.5 b 128.79 ± 2.53 c 94.16 ± 1.29 d 34.62 ± 1.24 ef 176.17 ± 2.12 f 82.00 ± 0.82 bc 31.91 bc 13.11 cd DOA2 6.87 b 11.0 b 232.00 ± 1.77 a 150.30 ± 1.59 b 81.71 ± 0.18 b 227.21 ± 4.07 c 76.92 ± 2.47 cd 30.81 bc 54.45 a Koshihikari 6.07 b 12.5 b 213.92 ± 0.83 b 152.04 ± 3.83 b 61.88 ± 4.66 c 224.55 ± 0.53 c 72.50 ± 3.30 d 31.74 bc 32.80 b Pin Kaset+4 5.44 b 13.0 b 218.67 ± 0.71 ab 191.38 ± 0.42 a 27.29 ± 1.12 f 282.08 ± 3.06 a 90.71 ± 3.48 a 26.19 c 5.21 cd Riceberry 8.81 a 23.0 a 59.34 ± 1.89 d 51.55 ± 1.60 e 7.79 ± 0.30 g 102.08 ± 2.12 g 54.05 ± 1.24 e 33.43 bc 2.53 d Different lowercase letters in the same column indicate significant difference at the 0.05 level using the LSD method.

Table 5. Correlation coefficients (r) of factors for all rice samples. Hot paste Cool paste Amylose Protein Variable Peak viscosity Breakdown Setback Hardness Adhesiveness viscosity viscosity content content Hot paste viscosity 0.847** Breakdown 0.713** 0.232 Cool paste viscosity 0.845** 0.987** 0.245 Setback 0.625* 0.718** 0.197 0.822** Amylose content 0.228 0.511* -0.256 0.536* 0.522* Protein content -0.408 -0.319 -0.327 -0.351 -0.350 -0.393 Hardness -0.295 -0.144 -0.350 -0.125 -0.033 -0.182 0.380 Adhesiveness -0.461 -0.210 -0.567 -0.168 0.051 0.331 0.260 0.121 Cooking time -0.353 -0.438 -0.069 -0.442 -0.322 -0.185 0.409 -0.299 0.382 * and ** represent significance at the 5% and 1% levels, respectively.

Uthomphon SAICHOMPOO, et al. Breeding Short Grain Rice in Koshihikari Background 487 with one another. AC is considered the most important candidate lines did not flower earlier than temperate determinant of cooked rice texture, and positive japonica varieties (AK and KH). Thus, the adaptability correlations between AC and HPV, CPV and SB were of the candidate lines to a tropical climate was found. The hardness had a negative correlation with AC improved relative to their indica parents. (r = -0.182), therefore, AC may not suitable to be The GYs of the four candidate lines during the three used as a parameter to predict the texture of cooked seasons were higher than those of KH and AK, but rice as suggested in other previous studies. were not significant for DOA1 and DOA2. Hosoi The two principal components explained a total of (1979) recommended that KH can be cultivated at 69.48% of the variation (Fig. 6-C). The first principal latitudes ranging from 31º N to 40º N, and it is component (PC1) accounted for 47.06% of the variation sensitive to high temperatures. Therefore, KH had a and seemed to differentiate rice samples according to lower GY in the Phan district of Thailand than at the their PV, HPV, CPV, SB and protein content values. latitude of 19º N. Thus, in this breeding program, The second principal component (PC2) accounted for methodological factors, including the air temperature, 22.42% of the variation and primarily explained the relative humidity and amount of rainfall between the textural attributes of cooked rice, and AC was wet and dry seasons were different, which then affected negatively correlated with BD. Positive correlations the agronomic traits and GY. However, it was confirmed were observed between PV and HPV, BD, CPV and that the four candidate short grain lines had good SB. In addition, to classify the candidate lines with agronomic traits and produced GY that were similar to control varieties using all the factors, four distinct those of the former varieties in a tropical climate. groups of rice were identified. The first was PinK4, which had a high AC, SB and PV. Second, KP48-1-5, Genetic background KP48-1-9 and BC95-2-7 were found to have similar Surprisingly, the genetic background of KP48-1-5, protein content, stickiness and hardness values. Third, which derived from the pedigree selection, was the BC95-2-12, BC95-2-14, KH and DOA2 were higher closest to that of KH, rather than the lines (BC95-2-12 in BD than the other varieties, and had other chemical and BC95-2-14) that came from the backcross method. and cooking properties that were notably more similar According to the theory of backcross breeding, 75% to each other. Finally, RB had the lowest values for of the genetic background in BC1 is close to the the pasting properties (SB, CPV, HPV, PV and BD), recurrent parent, while 50% of the genetic background and these unique characteristics made this rice variety in F2 during pedigree selection is close to the parent distinct from the other lines/ varieties. (Allard, 1960). In this breeding program, backcrossing DISCUSSION to the recurrent parent (KH) occurred until BC1 because KH is very sensitive to adaptation to tropical Agronomic and environmental factors regions. Thus, if the backcross process followed the Geographically, temperate japonica is cultivated in theory (until BC8), the genetic background of KH will temperate regions. Thus, the grain yields of temperate be increased in backcross progenies and then japonica rice grown in tropical regions are usually adaptability and agronomic performance may be 1–3 t/hm2, while the yields of temperate japonica rice decreased. However, the genetic background of grown in temperate areas are 4–6 t/hm2 (Kobayashi et al, BC95-2-14 derived from the backcross was closer to 2018). Most temperate japonica rice plants show that of AK, which is derived from KH × Ouu292 insufficient vegetative growth, premature flowering (Kobayashi et al, 2018). In addition, most of the and spikelet sterility under high temperatures, which selected breeding lines from BC1F4 and F5 were are the primary reasons for their poor growth and low identified in the japonica group. grain yields in tropical regions (Yoshida, 1983; Lee et al, Biotic stress resistance 2018). In this study, the short grain lines and control varieties showed clear differences in DF between the KH is very susceptible to leaf blast, moderately wet season (75 d in WS18 and 68 d in WS19) and dry susceptible to panicle blast and slightly resistance to season (91 d in DS19). This result can be explained by BLB in most paddy fields in Japan (Ishizaka et al, the average temperature during the wet season was 1989; Hori et al, 2017). By contrast, DOA1 and higher than that during the dry season by approximately DOA2 are susceptible to leaf blast, BLB and BPH 3 ºC in both the day and night. In addition, the (Warinrak, 2013). Therefore, this breeding strategy

488 Rice Science, Vol. 28, No. 5, 2021 used both molecular and conventional approaches to 18.86% in WS18 and WS19, respectively. Therefore, combine resistance to multiple biotic stresses, including the candidate lines were sufficient to produce good blast (Pi-ta), BLB (Xa21) and BPH resistance (TPS grain quality. In addition, the milled grain length to and Bph3) genes/QTLs in candidate lines, especially width ratio of the candidate lines was less than 2.0 for in KP48-1-5 and KP48-1-9. candidates identified as short grain types (Juliano and For BPH resistance, TPS and Bph3 genes were Villareal, 1993). This indicated that the breeding detected in the selected lines. The candidate lines did program derived from long grain (indica) × short grain not show higher levels of resistance than Ratuhinati (japonica) was successful in obtaining short grain rice (resistant check) because other resistance genes such by phenotyping with MAS (GS3). as Bph3, Bph14, Bph15 and Bph17 for BPH were not The cooking quality of rice primarily depends on introgress during this breeding program. KP48-1-5 AC, which determines the texture of cooked rice and and KP48-1-9, in which TPS and Bph3 were already the gelatinization temperature (Saleh and Meullenet, identified, were more resistant to BPH than the DOA1 2015). PinK4, the indica rice variety, had the highest and DOA2 varieties. AC, which resulted in a high gelatinization When considering BLB, Yugander et al (2017) temperature and high paste viscosity, but had less reported that single resistance gene for BLB cannot hardness than the others. This result may explain how provide durable resistance against the prevalent the structural characteristics of other chemical pathotypes. Thus, using a combination of three or four components such as protein influence cooked rice genes is broadly effective. However, among the quality (Hamaker and Griffin, 1993). Interestingly, various available BLB resistance genes, Xa21 is different observations regarding the correlations of reported to confer broad-spectrum resistance against AC, protein content and texture of cooked rice were Xoo races (Das and Rao, 2015). In this study, PinK4 not found in the candidate lines. This may be due to had xa5 and Xa21, while KH had only Xa21. However, the thickness of rice kernels. For example, PinK4 is all the candidate lines only had Xa21. This finding white rice while RB is colored rice. Moreover, Li et al suggested that the priority trait in this study is grain (2016) reported that the difference in cooking shape, while the xa5 gene was not identified in the properties between rice varieties may be due to their short grain phenotype from earlier generations. genetic make-up and differences in their granular However, the levels of resistance to BLB in the structure, such as the amylopectin chain length. candidate lines were better than those of KH and the The PCA results revealed that four distinct groups current varieties DOA1 and DOA2. of rice were identified based on physicochemical and The Pi-ta gene commonly used in rice breeding eating quality. There were clear distinctions between around the world originated from indica cultivars and the same indica varieties, PinK4 and RB, because one was introgressed into japonica cultivars to control rice is white rice and the other is purple rice. For the blast disease in the 1950s (Rybka et al, 1997). In this candidate lines, two groups were separated from each study, PinK4 (Ruengphayak et al, 2015), RB (unpublished) other, but members of each group were clustered and KH (Kobayashi et al, 2018) carried the Pi-ta gene. together without differences among accessions from the Thus, all the candidate lines contained this gene and indica and japonica groups. Three candidate lines, showed resistant to moderately resistant reactions KP48-1-5, KP48-1-9 and BC95-2-7, had higher scores against blast disease in every mixed strain group. for overall sensory quality and were in the same cluster that tended to have similar protein content Grain and cooking qualities (6%‒8%) and hardness properties (31‒45 N). However, Generally, japonica rice shows decreased cooking KP48-1-9, which had lower protein content and quality and a tendency towards decreased palatability moderate hardness, had the highest overall sensory when grown at daytime/nighttime temperatures exceeding score. The results were consistent with the findings of 28 ºC / 20 ºC (Chun et al, 2015; Zhao et al, 2017). In Xu et al (2018), who suggested that the overall general, the AC of KH is relatively low (17.5%) (Ise sensory quality is negatively correlated with protein et al, 2001). In this study, the AC of KH grown in content and positively correlated with hardness. WS18 and WS19 were 17.82% and 15.49%, Therefore, protein content and hardness can provide respectively, while the AC of the candidate lines good estimates for the eating quality of cooked rice. ranged between 19.34% to 20.16% and 17.27% to Similar characteristics between BC95-2-12 and

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KP48-1-9, including low protein content and moderate Technologies, Inc., USA). hardness were found, but the dissimilar factors were Screening SNP/InDel markers by Kompettitive Allele the pasting characteristics, in which BC95-2-12 Specific PCR (KASPTM) genotyping technology showed higher viscosity than KP48-1-9. Previous b studies reported that eating quality has significantly The SNP/InDel markers included starch (wx ), gelatinization positive correlations with minimum viscosity, final temperature (SSIIa), short grain (GS3), aroma (badh2), blast viscosity and setback (Nakamura et al, 2004; Tong et al, resistance (Pi-ta), BLB (xa5 and Xa21), BPH (Bph3 and TPS) and submergence tolerance (Sub1C) genes were conducted in 2014). Therefore, candidate lines with high eating F2, F5 and F7 (Table S1). All KASP genotyping was performed quality tended towards low hardness and viscosity. using the LGC SNP line system following the standard KASP The overall results indicated that genetic factors as protocols (LGC Group, 2016). The thermal cyclers of PCR is well as physicochemical properties are involved in shown in Table S2. Finally, the PCR products were analyzed creating different variations in eating quality traits in for their genotypes using PHERAstarPlus SNP (LGC, Serial the crossbred lines among indica and japonica rice. No. 470-0319, Middlesex, UK). An ideal rice variety should exhibit a high yield, Breeding schemes stable performance over a wide range of environments and good cooking quality. Therefore, four promising The breeding program for short grain rice involved the pairwise short grain breeding lines, KP48-1-5, KP48-1-9, crossing is shown in Fig. 1. First, KH was crossed with RB to BC95-2-12 and BC95-2-14, exhibited good agronomic obtain F1 seeds that were then divided two ways. The resulting performance (Fig. S2) and maintained grain yields that F1 plants were backcrossed to KH to produce BC1F1 and selfed were not lower than those of the DOA1 and DOA2. to produce F2 seeds. After that, the pedigree selection was used Moreover, MAS can introgress multiple genes for for selection in both methods until BC1F6 and F7, respectively. biotic stress resistance and grain quality into The second crossing, KH was crossed with PinK4 to obtain F1 seeds and then selfed to produce F seeds. After that the promising lines. In addition, the four promising lines 2 pedigree selection was used for selection until F7. The standard had high sensory test values and cooked taste scores japonica grain shape (Juliano and Villareal, 1993) was used as that were close to those of KH and DOA2. In the a criterion for phenotypic selection. future, the four promising lines will be subject to yield The selected lines in the BC1F4 and F5 resulting from trials on a farmer’s fields to confirm the potential and pairwise crossing were grown for a preliminary yield trial with to evaluate farmer satisfaction. Subsequently, the best the parents and control varieties (RB, PinK4, KH, AK, DOA1 line will be released as a commercial variety in the and DOA2) during WS18 (June–September, 2018). The northern part of Thailand. experiment was conducted as a randomized complete block design (RCBD), with three replications. The plot size for each METHODS treatment was 2.5 m × 2.5 m with a spacing of 25 cm × 25 cm. The yield trial experiments on the BC F and F were Growth conditions 1 5 6 conducted during DS19 (January‒April, 2019), and then the

The study was conducted from 2015 to 2019 at Tana Grain BC1F6 and F7 were validated with the parents and control Polish, Ltd., Phan district, Chiang Rai Province, Thailand varieties during WS19 (June‒September, 2019). The RCBD (19º35′ N, 99º44′ E, 413 m above sea level). The rice plants with three replications was applied during both seasons. The were seeded in a field nursery. After 30 d, the rice seedlings plot size for each treatment was 2.5 m × 3.5 m with a spacing were transplanted into breeding plots. The soil in the Phan of 20 cm × 20 cm. district consisted of 1.56% organic matter, 0.07% total N, 26.70 Agronomic trait determination during yield trials mg/kg available P, 75.54 mg/kg exchangeable K, 629.0 mg/kg exchangeable Ca and 76.50 mg/kg exchangeable Mg, and had a The agronomic traits examined included DF, plant height, pH of 5.40. Additionally, basal fertilizer was applied at 15 d number of tillers per plant, number of panicles per plant, after planting at a rate of 33.7 kg/hm2 of N (diammonium 1000-grain weight and GY. These traits were determined for 2 phosphate) and 41.3 kg /hm of P2O5. The second split of rice plants grown during field trails in 2018 and 2019. DF was fertilizer was applied at the booting stage (65 d after planting) recorded when 100% of the individual plants in each plot at a rate of 57.5 kg /hm2 of N. Other management practices flowered. Plant height, number of tillers per plant and number were performed in accordance with conventional high yielding of panicles per plant were measured at maturity. GY in each cultivation approaches. The weather data, including air plot was determined by finding the per harvested area of 6.25 temperature, relative humidity and amount of rainfall in the or 8.75 m2. The grain moisture was adjusted to 14% and then field, were measured every 3 h each year (2015‒2019) with a extrapolated to units of kg/hm2. Following threshing, the grains data logger (WatchDog 2000 Series Micro Stations, Spectrum were weighed to obtain the 1000-grain weight.

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Evaluation of grain quality Evaluation of biotic stress resistance

The dried grains were stored at room temperature for one BPH resistance screening month prior to the grain quality evaluation. Paddy grains (300 g) Three BPH populations Kamphaeng Phet, Sing Buri and Ta were sampled from each replicate. The paddy grains were Phaya were used to screen BPH resistance in the candidate dehulled and polished using a mini-polisher. Three physical lines and their parents with susceptible (TN1) and resistant grain qualities, namely, grain length, grain width and grain (Ratuhinati) check varieties. Standard seed box screening was length to width ratio of both paddy rice and milled rice, were conducted at the seedling stage under greenhouse conditions measured by using a two-decimal-point digital Vernier caliper. according to Heinrichs et al (1985). Damage scores were Three chemical grain qualities, gelatinization temperature (GT), recorded by using a standard system for evaluating damage AC and protein content, were evaluated according to Juliano (IRRI, 2013). (1985). BLB resistance screening Evaluation of cooking quality CN1-3, NP3-5, XORE1-1, CR2-4, SK1-2 and XON2-1 isolates Cooking characteristics including cooking time and the texture (Wonglom et al, 2015) were used to screen BLB resistance in of cooked rice were studied on polished rice samples. Cooking the candidate lines and their parents with susceptible time of the rice samples was determined according to Juliano (KDML105) and resistant (PYBB-36) check varieties. Each (1985). A textural analysis of cooked rice samples was isolate was grown following the methods described by Win et al conducted with a texture analyzer equipped with a 35 mm (2012). The inoculation method was followed Theerayout et al cylindrical probe attachment (TA.XT Plus, Stable Micro (2009). The resistance reaction was classified as resistant, System Corp., UK) according to Li et al (2016) with moderately resistant, moderately susceptible and susceptible modifications. The pasting properties of the rice flours were described by Yang et al (2003). evaluated according to the AACC method (AACC, 2000). The viscosity changes were measured using a Rapid Visco Analyzer Leaf blast resistance screening (RVA, Model 4-D, Newport Scientific, Australia). Seven mixed groups of Thai Magnaporthe oryzae (Table S3) were used to screen blast resistance in candidate lines and their Evaluation of sensory quality of cooked rice parents with Sariceltik (resistant) and JHN (susceptible) The rice cooking procedure by Xu et al (2018) was applied. varieties. The screening protocol was followed Marchetti et al The rice was cooked using the preset cooking setting of a rice (1987) and the disease scoring was recorded on a standard cooker (Sharp model KS-ZT18, Thailand). Seven panelists who system for evaluating damage (IRRI, 2013). had been well-trained in the principles and concepts of Statistical analysis descriptive sensory analysis participated in the sensory quality evaluation. The sensory items included smell (scores 1‒5), All the data were analyzed using R program version 3.6.1 to appearance (scores 1‒5), stickiness (scores 1‒5), softness test the significance of the agronomic trait and cooking quality (scores 1‒5) and taste (scores 1‒5). A comprehensive results. The means were separated using the Duncan’s test at assessment was made based on the above factors. Using a alpha levels of 0.05. If there was significant difference among relative scale, the panelists gave a score for each attribute the experiments for a given parameter, then the values from all compared with the reference sample attributes, and the overall of the experiments for that parameter were used to obtain the quality was the sum of the scores for all the attributes. means and standard error. PCA was employed to reduce the complexity of the data. In addition, the AMMI model was used Phylogenetic analysis based on GBS to analyze the G × E interactions (Gauch, 1988). To determine the genetic background of the breeding lines ACKNOWLEDGEMENT (BC1F4 and F5) compared with their parents, a phylogenetic analysis was performed. DNA from the rice leaves was isolated This study was supported by the Tana Group International Co. according to the DNeasy Plant Mini Kit (Qiagen, Germany) Ltd., Thailand (2015‒2019). protocol, and then sequenced on an Illumina HiSeq X by Novogene AIT, Singapore. The Bowtie 2 program was SUPPLEMENTAL DATA subsequently used to align the nucleotides (Langmead and The following materials are available in the online version of Salzberg, 2012), and the GATK program was used to analyze this article at http://www.sciencedirect.com/journal/rice-science; the single-nucleotide polymorphisms (SNPs) in each sample http://www.ricescience.org. (McKenna et al, 2010). Finally, the nucleotide sequences from Fig. S1. Weather data from WS15‒WS19 in Phan district, the breeding lines and control varieties were used to construct a Chiang Rai Province, Thailand. phylogenetic tree using the MEGA X program. Fig. S2. Phenotypes of four promising lines and their parents in

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wet season in 2019. of Cereal Chemists (AACC): 443–513. Table S1. Gene-based/linked markers used for foreground Juliano B O, Villareal C P. 1993. Grain Quality Evaluation of selection of biotic resistance, abiotic tolerance and cooking World Rice. Manila, the Philippines: International Rice Research quality for their validation in the breeding lines. Institute. Table S2. Thermal cycling conditions for polymerase chain Kang K H. 2010. Made for the TROPICS. Rice Today, 9: 34–35. reaction amplification used by HydrocyclerTM. Kobayashi A, Hori K, Yamamoto T, Yano M. 2018. Koshihikari: Table S3. Seven mixed strain groups of blast diseases in A premium short-grain rice cultivar: Its expansion and breeding Thailand as classified by amplified fragment length in Japan. Rice, 11: 15. polymorphism. Langmead B, Salzberg S. 2012. Fast gapped-read alignment with Bowtie 2. Nat Methods, 9: 357–359. REFERENCES Lee J S, Torollo G, Ndayiragije A, Bizimana J B, Choi I R, Gulles AACC. 2000. Approved Methods of the American Association of A, Yeo U S, Jeong O Y, Venkatanagappa S, Kim B K. 2018. Cereal Chemists. 10th edn. St. Paul, MN, USA: America Association Genetic relationship of tropical region-bred temperate japonica of Cereal Chemists, John Wiley & Sons Inc. rice () plants and their grain yield variations in three Allard R W. 1960. Principles of Plant Breeding. New York, USA: different tropical environments. Plant Breeding, 137: 857–864. John Wiley & Sons Inc. LGC Group. 2016. SNPline genotyping automation. https://www. Chun A, Lee H J, Hamaker B R, Janaswamy S. 2015. Effects of lgcgroup.com/products/genotyping-instruments/snpline/#.XFCv ripening temperature on starch structure and gelatinization, 91xKhaQ. (Accessed 5 January 2020) pasting, and cooking properties in rice (Oryza sativa). J Agric Li H, Prakash S, Nicholson T M, Fitzgerald M A, Gilbert R G. Food Chem, 63: 3085–3093. 2016. The importance of amylose and amylopectin fine structure Das G, Rao G J. 2015. Molecular marker assisted gene stacking for for textural properties of cooked rice grains. Food Chem, 196: biotic and abiotic stress resistance genes in an elite rice cultivar. 702–711. Front Plant Sci, 6: 698. Marchetti M A, Lai X, Bollich C N. 1987. Inheritance of resistance Gauch H G. 1988. Model selection and validation for yield trials to Pyricularia oryzae in rice cultivar grown in the United States. with interaction. Biometrics, 44: 705–715. Phytopathology, 77: 799–804. Hamaker B R, Griffin V K. 1993. Effect of disulfide bond-containing McKenna A, Hanna M, Banks E, Sivachenko A, Cibulskis K, protein on rice starch gelatinization and pasting. Cereal Chem, Kernytsky A, Garimella K, Altshuler D, Gabriel S, Daly M, 70: 377–380. DePristo M A. 2010. The genome analysis toolkit: A MapReduce Heinrichs E A, Medrano F G, Rapusas H R. 1985. Genetic Evaluation framework for analyzing next-generation DNA sequencing data. for Insect Resistance in Rice. Los Banos, the Philippines: Genome Res, 20: 1297–1303. International Rice Research Institute. Miyamoto M. 2017. Influence of changing Thai society on the Hori K, Yamamoto T, Yano M. 2017. Genetic dissection of Japanese restaurant industry in Thailand. Manusya: J Hum, 20: agronomically important traits in closely related temperate 13–32. japonica rice cultivars. Breeding Sci, 67: 427–434. Nakamura S, Okadome H, Yoza K, Haraguchi K, Okunishi T, Hosoi N. 1979. Studies on meteorological fluctuation in the growth Suzuki K, Sato H, Ohtsubo K. 2004. Differentiation and search of rice plants: III. Relation between the heading response of rice for palatability-factors of world-wide rice grains by PCR method. varieties to temperature under natural daylength and the thermos- J Jpn Soc Food Sci, 78: 764–779. (in Japanese with English sensitivity, photosensitivity, basic vegetative growth under abstract) controlled environments. Jpn J Breeding, 29: 294–304. (in Nakwilai P, Cheabu S, Narumon P, Saensuk C, Arikita S, Japanese with English abstract) Malumpong C. 2020. Evaluation of japonica rice (Oryza sativa International Rice Research Institute (IRRI). 2013. Standard L.) varieties and their improvement in terms of stability, yield Evaluation System (SES) for Rice. 5th edn. Los Banos, Manila, and cooking quality by pure-line selection in Thailand. Sci Asia, the Philippines: International Rice Research Institute: 46. 46: 157–168. Ise K, Akama Y, Horisue N, Nakane A, Yokoo M, Ando I, Hata T, Poosri S, Thilavech T, Pasukamonset P, Suparpprom C, Adisakwattana Sito M, Numaguchi K, Nemoto H. 2001. ‘Milky queen’, a new S. 2019. Studies on Riceberry rice (Oryza sativa L.) extract on high-quality rice cultivar with low amylose content in endosperm. the key steps related to and digestion and Bull Natl Inst Crop Sci, 2: 39–61. (in Japanese with English absorption: A new source of natural bioactive substances. NFS J, abstract) 17: 17–23. Ishizaka S, Uehara Y, Fujita Y, Okuno K, Horiuchi H, Miura K, Ruengphayak S, Chaichumpoo E, Phromphan S, Kamolsukyunyong Nakagahra M, Yamada T, Uchiyamada H, Samoto S. 1989. W, Sukhaket W, Phuvanartnarubal E, Korinsak S, Korinsak S, Breeding process and characteristic of new released variety Vanavichit A. 2015. Pseudo-backcrossing design for rapidly Kinuhikari. Hokuriku Crop Sci, 24: 25–27. (in Japanese) pyramiding multiple traits into a preferential rice variety. Rice, 8: Juliano B O. 1985. Criteria and test for rice grain quality. In: Rice 7. Chemistry and Technology. Saint Paul, USA: American Association Rybka K, Miyamoto M, Ando I, Saito A, Kawasaki S. 1997. High

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resolution mapping of the indica-derived rice blast resistance variety KDML105 for non-age-related broad-spectrum resistance genes: II. Pi-ta2 and Pi-ta and a consideration of their origin. to bacterial blight disease based on combined marker-assisted Mol Plant Microbe Interact, 10: 517–524. and phenotypic selection. Field Crops Res, 137: 186–194. Seemanon K, Yamao M, Hosono K. 2015. Production of Japanese Wonglom P, Watcharachaiyakup J, Patarapuwadol S, Kositratana rice through contract farming system in Wiang Pa Pao district, W. 2015. Assessment of diversity among pathotype of Xanthomonas Chiang Rai Province, Thailand. Am J Rural Dev, 3(2): 41–51. oryzae pv. oryzae prevalent in Thailand. Agric Sci J, 46(2): Saleh M, Meullenet J F. 2015. Cooked rice texture and rice flour 165–175. (in Thai with English abstract) pasting properties; impacted by rice temperature during milling. Xu Y J, Ying Y N, Ouyang S H, Duan X L, Sun H, Jiang S K, Sun J Food Sci Technol, 52: 1602–1609. S C, Bao J S. 2018. Factors affecting sensory quality of cooked Tao K, Yu W, Prakash S, Gibert R G. 2020. Investigating cooked japonica rice. Rice Sci, 25(6): 330–339. rice textural properties by instrumental measurements. Food Sci Yang Z, Sun X, Wang S, Zhang Q. 2003. Genetic and physical Hum Wellness, 9(2): 130–135. mapping of a new gene for bacterial blight resistance in rice. Theerayout T. 2009. Identification of microsatellite markers (SSR) Theor Appl Genet, 106: 1467–1472. linked to a new bacterial blight resistance gene xa33(t) in rice Yoshida S. 1983. Rice. In: Smith W H, Banta S J. Potential cultivar ‘Ba7’. Maejo Int J Sci Technol, 3: 235–247. Productivity of Field Crops under Different Environments. Los Tong C, Chen Y L, Tang F F, Xu F F, Huang Y, Chen H, Bao J S. Baños, the Philippines: International Rice Research Institute: 2014. Genetic diversity of amylose content and RVA pasting 103–127. parameters in 20 rice accessions grown in Hainan, China. Food Yugander A, Sundaram R M, Ladhalakshmi D, Hajira S K, Chem, 161: 239–245. Prakasam V, Prasad M S, Madhav M S, Babu V R, Laha G S. Wada T, Yasui H, Inoue T, Tsubone M, Ogata T, Doi K, Yoshimura 2017. Virulence profiling of Xanthomonas oryzae pv. oryzae A, Matsue Y. 2013. Validation of QTLs for eating quality of isolates, causing bacterial blight of rice in India. Eur J Plant japonica rice ‘Koshihikari’ using backcross inbred lines. Plant Pathol, 149: 171–191. Prod Sci, 16(2): 131–140. Zhao C J, Xie J Q, Li L, Cao C J. 2017. Comparative transcriptomic Warinrak B. 2013. Japonica Rice Production Technology in analysis in the paddy rice under storage and identification of Thailand. Rice Department, Thailand: CRC. (in Thai) differentially regulated genes in response to high temperature Win K M, Korinsak S, Jantaboon J, Siangliw M, Lanceras- and humidity. J Agric Food Chem, 65: 8145–8153. Siangliw J, Sirithunya P, Vanavichit A, Pantuwan G, Jongdee B, (Managing Editor: WU Yawen) Sishiwong N, Toojinda T. 2012. Breeding the Thai