INHERITANCE of ALTERNARIA RESISTANCE in WHEAT Division
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INHERITANCE OF ALTERNARIA RESISTANCE IN WHEAT S. S. SOKHI*, L. M. JOSHI and M. V. RAO Division of Mycology and Plant Pathology, I.A.R.I., New Delhi (Accepted: 22-viii-73) LEAF blight of wheat has become of great concern in recent years in some parts of India as many of the varieties in cultivation are susceptible in one part or other of the country. The disease has become important, in recent years in Maharashtra, Bihar and West Bengal. The disease was first recorded in 1924 by Kulkarni from Bombay and by McRae from Bihar. A few subsequent reports on the disease appeared from U.P. (Mehta, 1960; Mathur, 1950), Orissa (Bose, 1956) and Andhra Pradesh (Rao, 1961). However, in all the above case the pathogenicity was not established by inoculation experiments and the causal organisms was not identified. Prasada and Prabhu (1962) identified the causal organism as a new species, Alternaria triticina. Some of the varieties such as Kenphad wheats and some Mexican wheats and their derivatives are susceptible to the disease. At present, the disease is ranked as one of the major diseases of wheat and causes substantial damage to the crop. The progress in respect of breeding varieties resistant to the disease would depend upon the knowledge of various sources of resistance and the mode of inheritance of genes for resistance. The present investigations report the results of such studies. www.IndianJournals.com Members Copy, Not for Commercial Sale MATERIALS AND METHODS Downloaded From IP - 61.247.228.217 on dated 27-Jun-2017 The mode of inheritance of jAltemaria blight resistance was studied in Fr and F2 of different crosses of 8 parents involving 7 resistant parents, viz., Agra Local, NP4 , NP53) NP809, NP824, E. 581 and E. 1912, and one susceptible (NP. 830). The Fi seed of all these crosses was sown at Wellington and F s seed was brought for testing for reaction against Alternaria triticina under Delhi conditions. Inoculation with spore suspension of Delhi isolate (16,000 spores/ml) of A. triticina was done in the evening when the crop was 80 days old. After inoculation a heavy irrigation was given to the crop to create a humid microclimate for causing heavy infection. Observations were recorded by modified McKinney's technique as applied by Horsfall and Heuberger (1942) following 0 to 10 infection categories. The plants showing 0, 1 and 2 reactions were put under resistant class, 3, 4, 5, 6, 7, 8, 9 and 10 were put under susceptible class. The disease reactions of all the segregating material were recorded when there was full expression of the disease. RESULTS AND DISCUSSION The F, generation of crosses of NP 830 with five resistant parents viz., Agra Local, NP 52, NP 824, NP 4 and NP 809 exhibited dominance of suscep- tibility to the disease but in the crosses with the resistant wheats, E 1912 and •Present address: Division of Plant Pathology, Indian Instt. of Horticultural Research, Bangalore-6 457 458 Indian Journal of Genetics & Plant Breeding [Vol. 33, No. 3 E 581 susceptibility was recessive. Data on the mode of segregation in crosses of the 7 resistant parents with susceptible variety NP 830 are presented in Table 1. From the above data it appears that the resistance of Agra Local, NP 52 and NP 4 to leaf blight is governed by one recessive gene pair whereas, in NP 824 and NP 809, it is controlled by two recessive gene pairs. The resistance of E 1912 and E 581 is governed by dominant genes, three in the former and one in the latter. In order to establish the diversity of genes carried by resistant varieties, the F2 of 21 crosses involving the above 7 resistant parents were tested against the disease. TABLE 1 Mode of segregation of resistance to A. triticina in the F2 population of 7 crosses No. of plants Gross Generation X2 Resistant Susceptible NP 830 X Agra Local F2 (obs.) 74 210 •168 F2 (exp.) (1:3) 71 213 NP 830 x NP 52 F3 (obs.) 41 141 •666 F2 (exp.) (1:3) 45-5 136-5 NP 830 x NP 824 F, (obs.) (1:15) 11 129 •617 F„ (exp.) 8-75 131-25 NP 830 x NP 4 F2 (obs.) 80 282 1-626 F2 (exp.) (1:3) 90-50 271-50 www.IndianJournals.com NP 830 x NP 809 F2 (obs.) 12 129 1-231 Members Copy, Not for Commercial Sale F2 (exp.) (1:15) 8-91 132-19 NP 830 x E 1912 F2 (obs.) 240 3 0-171 Downloaded From IP - 61.247.228.217 on dated 27-Jun-2017 F2 (exp.) (63:1) 239-2 3-8 NP 830 x E 581 Fa (obs.) 96 28 0-387 F3 (exp.) (3:1) 93 31 The recessive gene controlling disease resistance in Agra Local is also found in the varieties NP 52 and NP 4 where resistance is controlled by a single pair of recessive genes. This gene appears to be one of the two genes present in the varieties NP 809 and NP 824 where resistance is controlled by two recessive duplicate genes. The duplicate recessive genes in NP 809 and NP 824 appear to be the same. One of the factors present in E 1912 is common to the one present in the variety E. 581 where resistance is controlled by dominant genes. Recently Narula and Srivastava (1971) studied the genetics of Alternaria resistance in wheat where they reported that resistance in varieties NP 835, NP 852 and G 306 is governed by two pairs of recessive genes. In the present studies in all the 5 Indian wheats resistance was either controlled by a single or two duplicate recessive genes. November, 1973] Alternaria resistance in wheat 459 All the varieties which showed resistance to Alternaria in the present studies are susceptible to brown rust. Similar relationship had been observed in oat varieties where susceptibility to Helminthosporium victoriae and resistance to Puccinia coronata appears to be always associated. Reddy (1967) and Sokhi (1971) concluded that amongst the various mechanisms of disease resistance in Alternaria blight, sugar content may play a part in some varieties like Agra Local but not in all the resistant varieties. Prabhu and Swaminathan (1968) have stated that low sugar content of Agra Local may be one of the pathways of resis- tance in this variety. However, this hypothesis proposed by Horsfall and Dimond (1957) does not hold true in all cases. It may, therefore, be possible to locate simultaneous resistance to brown rust and Alternaria blight. These two pathogenes have synergestic effect and cause more loss together that the sum total of the loss caused by the individual fungi (Sokhi, 1971). It is, therefore, desirable to identify simultaneous sources of resistance to both the pathogens. SUMMARY Inheritance of resistance to Alternaria blight of wheat was studied in a set of diallel crosses of 8 parents involving 7 resistant parents Agra Local, NP 52, NP 824, NP 4, NP 809, E 1912 and E 581 and a susceptible parent, NP 830. Resistance to leaf blight was governed by a pair of recessive genes in the varieties, Agra Local, NP 52 and NP 4 and by two pairs of recessive genes in varieties NP 824 and NP 809. In varieties Timenstein x Mida (E 1912) and Kenya 184. P.2. A.I.F. (E 581) resistance was controlled by three and one pair of dominant genes, respectively. www.IndianJournals.com Members Copy, Not for Commercial Sale ACKNOWLEDGEMENTS Authors are thankful to Dr. S. P. Raychaudhuri, Head, Division of Mycology and Plant Pathology, Downloaded From IP - 61.247.228.217 on dated 27-Jun-2017 IARI, New Delhi, for providing necessary facilities. S. S. Sokhi is thankful to ICAR for awarding Sr. ICAR fellowship during the tenure of his studies. REFERENCES Bose, S. R. (1956). Alternaria within the pericarp of wheat Nature, Land., 178: 640-641. Horsfall, J. G. and Heuberger, J. W. (1942). Measuring magnitude of a defoliation disease of tomatoes. Phytopathology, 32: 226-232. Horsfall, J. G. and Dimond, A. E. (1957). Interactions of tissue sugar, growth substances and disease susceptibility. Z- Pflanzenkrankh u PJlanzenschutz. 64: 415^21. Mathur, R. S. (1956). Alternaria leaf spot of wheat in U. P. Agric. Anim. Husb., U.P. 6: 12-14. Mehta, P. R. (1950). Some new diseases of plants of economic importance in U. P. PI. Prot. Bull., New Delhi, 2: 50-51. Nirula, P. N. and Srivastava, O. P. (1971). Genetics of Alternaria resistance in wheat. Indian J. Genet., 31:105-107. Prabhu, A. S. and Swaminathan M. S. (1968). Inverse relationship between resistance to rusts and leaf blight of wheat. Curr. Sci., 37: 379-80. Prasada, R. and Prabhu, A. S. (1962). Leaf blight of wheat caused by a new species of Alternaria. Indian Phytopath., 15: 292-93. Rao, G. P. (1961). Proceedings of All India Wheat Research Worker's Seminar, I. A. R. I. New Delhi. Reddy, A. P. K. (1967). Physiologic studies of Alternaria triticina Prasada and Prabhu, the causal agent of leaf blight of wheat. Unpub. Ph.D. thesis, IARI, Mew Delhi. Sokhi, S. S. (1971). Studies on leaf blight of wheat caused by Alternaria triticina with special reference to the disease resistance. Unpub. Ph. D. thesis, I.A.R.I., New Delhi. .