id25503277 pdfMachine by Broadgun Software - a great PDF writer! - a great PDF creator! - http://www.pdfmachine.com http://www.broadgun.com ISSN : 0974 - 7532 Volume 10 Issue 4 Research & Reviews in BBiiooSScciieenncceess Review RRBS, 10(4), 2015 [137-146] Inheritance of resistance to loose smut ustilago tritici of wheat Reda Helmy Sammour1*, Mostafa Mahmoud El Shamy2, Abd El-Zaher M.A. Mustafa1, Enas Said Yousef El-Refaay2 1Botany Department, Faculty of Science, Tanta University, (TANTA) 2Gemmeiza Agriculture Research, Gemmeiza, Agricultural Research Center, El-Giza, (EGYPT) E-mail: [email protected] ABSTRACT Ustilago tritici, the causal agent of loose smut of wheat (Triticum aestivum L), belongs to family Ustilaginaceae. In nature, infection by Ustilago segetum var. tritici is organ specific i.e. via the ovary, and it is possible only during the relatively short period of flowering of the host. In the field, there are two methods of inoculation; dry method and wetable method. An extensive work has been done in many countries of the world for identifying sources of resistance to that disease, since breeding for resistance may be one of the most effective methods for controlling the disease. Loose smut causes a reduction in agronomic charactesrs. Yield is an ultimate product of the action and interaction of a number of quantitative characters, which are known to be controlled by different sets of polygenes. Therefore, ombining ability studies are used by plant breeders to select parents with maximum potential of transmitting desirable genes to the progenies. The estimation of combining ability is very useful because the variance due to general combining ability is attributed to additive gene action, while the variance due to specific combining ability is attributed to non-additive gene action. The inheritance of heterosis could be help to select some superior parents and cross combinations for further exploitation in breeding programme either agronomic traits or resistance to plant disease and proved that resistance was dominant to susceptibility. The results indicated at least one major gene and one minor gene segregation for resistance and transgressive segre- gation for these parents differed in genes for resistance. Improvement of quality in wheat (Triticum aestivum L.) depends on the influence of environmental conditions and their interactions. Loose smut causes damage by destroying the infected plants and reducing the quality of grain of the non-infected plants upon harvest. Embryo test for detecting the dormant mycelia in the infected seeds has extensive importance, since a direct correlation was observed between the level of embryo infection and the incidence of loose smut in the field. It was stated that the total nitrogen content of the host- pathogen complex generally increased during the early stage of disease. Increase in secreted protein play important role during pathogenesis and thought to act as effectors for modulat- ing the plant response. Fungus penetration and growth through cells as well as disintegration of plant cell wall at later stages requires lytic enzymes. 2015 Trade Science Inc. - INDIA INTRODUCTION and it found in all wheat-growing areas of the world, being particularly in humid areas[1-2]. Ustilago tritici, the causal agent of loose smut Symptoms of wheat loose smut disease of wheat (Triticum aestivum L), belongs to family ’s Ustilaginaceae; order Ustilaginales; class, Ustilago segetum tritici is a basidiomycete Teliomycetes; division, Eumycota. Loose smut is fungus that infects wheat during flowering (floral in- considered a serious seed-borne disease of wheat fecting smut).Teliospores are carried into the flower 138 Inheritance of resistance to loo.se smut ustilago tritici of wheat RRBS, 10(4) 2015 Review by wind and settle mainly at the shoulder of the ovary. Dry method The spores germinate and dicaryotic infectious hy- For inoculation, dry spores of loose smut are phae invade the developing seed by penetration of introduced into the florets with forceps or a small the pericarp. The fungus grows through the seed coat brush, by a puff of air over tiny pieces of paper or into the scutellum and embryo at the base of the ball of cotton containing spores, or by dusting spores seed[3-5]. After germination of the seed, the mycelia over entire spikes[29-32]. Other inoculation method permeate the crown node and enter the growing point inculde: partial vacum[33-37] air blast[38-40]. Joshi et of the tillers. The fungus is carried passively up with al.[41] developed this method by removing of central the plant growing point, which eventually develops floret of each spikelet and clip the glumes of the two into a smutted ear[3]. Neither the infected seed nor remaining florets to expose the stigma and anthers the developing plants show any obvious or unam- then cover the spike with a paper bag and before biguous macroscopic symptoms until appearance of anthesis is complete use a smutted spike to dust infected ears[6-8]. teliospores onto the clipped spike. Pandey and Epidemiology of loose smut in Egypt Gautam[42] stated that the dry spore method for in- Wheat has been attacked with many destructive oculation with loose smut (Ustilago segetum diseases such as rusts, smuts, mildews and some var.nuda) seems adequate for initial germplasm other diseases of minor importance[9-12]. In Egypt, screening and inheritance studies but for more rig- wheat loose smut, caused by Ustilago segetum var. orous screening of advanced breeding material the tritici ranked the second serious disease following modified partial vacuum method may be preferred. rusts. The first record of wheat loose smut caused Wetable method by Ustilago tritici was in 1888 as a result to ex- change of seed between countries. In 1949, the losses The spore suspension was injected into the flo- [43-47] of wheat yield ranged between trace to 5% on the ret using a rubber ball or a syringe and hypo- [48-50] [51] local and Indian varieties. Since that date, the dis- dermic needle . Zadoks et al. stated that in- ease disappeared for long time due to realizing the oculum of individual races was prepared at a rate resistant varieties Giza -139, Giza- 144 and Giza of about 1 mg of spores per 1 ml of tap water. At 155[13-16]. Then, it was recorded at 1984/1985 on anthesis growth stage, individual florets were in- some varieties Sakha 61, Sakha 69 and Giza-163. oculated with the spore suspension using a 10- ml [52] During the period from 1985-1989, annual loose smut syringe to pierce the palea. Wilcoxson et al. used survey was performed in 16 Governorates, revealed vacuum procedure for inoculation of oat (Avena sa- that disease incidence was about 0.1% on the com- tiva) parental varieties and lines and progenies mercial varieties i.e. Sakha 61 and Sakha -69[17-20]. (Ustilago avenae) with water suspensions of loose Methods of inoculation with loose smutIn na- smut teliospores. Willits and Sherwood[53] used a ture, infection by Ustilago segetum var. tritici is modification of the vacuum inoculation method in organ specific i.e. via the ovary, and it is possible which seeds of each barley cultivar were dehulled only during the relatively short period of flowering and surface-sterilized for 5 min in 5.25% sodium of the host[21-24]. Teliospores enter the floret, germi- hypochlorite. A total of 30 seeds were inoculated nate and form dikariotic hyphae that infect the ovary, by adding approximately 25 mg of race 8 teliospores usually at the brush end[9,25,28]. The mycelium enters to the seeds with 0.5 mg of carboxy methylcellulose the upper and side parts of the scutellum 10 to 15 and 1 ml of sterile water containing 0.001% Tween days after penetration and grows through the hypo- 20. The seeds were vacuum-infiltrated three times cotyls into the plumular bud, or growing point of the for 10 min, dried, and planted in damp vermiculite embryo, where it will lie dormant in the mature seed. at a depth of 3 cm. Mau et al.[54] inoculate plants at Most of field inoculation methods developed to anthesis with loose smut when the first anthers of – spike had extruded and started to turn white. simulate natural conditions. There are two methods the mid of inoculation. Inoculum was prepared by placing a piece of an in- RRBS, 10(4) 2015 Ronald Bartzatt 139 Review fected spike into 50 ml bottle with 10 ml of distilled highly susceptible in the embryos stage to a race of water. loose smut and highly to the same race in seedling [70] Time of inoculation and adult plant stages. Ohms and Bever found that Kawval wheat cv. was resistance to 3 physiologic After heading, plants with sporulation stop grow- races of Ustilago tritici viz. 1, 3, and 11. On the ing. The lower internodes are usually longer and the other hand, Wabash wheat cv. was susceptible to upper ones shorter than in healthy plants, but the pe- race 1 and 3 but resistance to race 11. No differ- duncle of the spike with sporulation is much shorter. ences were observed between both of tested em- The leaf sheaths of some infected cultivars are grey- bryos of the two cvs., Kawval showed infection in ish-purple; the leaves, particularly the flag leaf, are scutella only while the latter exhibited infection in reduced in size, often yellowed and senesce early[55- both scutella and growing point. Mishra et al.[71] 57]. For maximum infection, the wheat floret inocu- stated that of 92 cultivars screened against U. lated at early mid- anthesis growth stage. At this Segetum var. tritici by needle inoculation during stage, the first anthers of mid-spike had extruded and 1980-82, 15 were designated as resistant and 3 as started to turn white[58].