Study finds dis­ease re­sis­tance in wheat germplasm

The re­sults of the study are of great prac­ti­cal sig­nif­i­cance keep­ing in view the con­tin­u­ous search of genes for breed­ing mul­ti­ple rusts re­sis­tant wheat va­ri­eties

Rural & Marketing - - CASE STUDY -

Thanks to the con­tin­u­ous ef­forts of agri­cul­ture sci­en­tists in crop im­prove­ment and mak­ing the new va­ri­eties more re­sis­tant to var­i­ous types of dis­eases, since Green Rev­o­lu­tion, India has never seen back in food grain pro­duc­tion. One sig­nif­i­cant con­straint to in­creased wheat pro­duc­tion is the variety of rust dis­eases at­tack­ing this crop— leaf rust, stem rust and stripe rust. Sources of re­sis­tance to these dis­eases are known, and have been utilised by wheat breed­ers for a long time. How­ever, achiev­ing durable re­sis­tance can be dif­fi­cult, and the rust dis­eases con­tinue to evolve and cir­cum­vent the breed­ers' achieve­ments. Rust is spread­ing in dif­fer­ent wheat grow­ing re­gions in re­cent past and the Food and Agri­cul­ture Or­ga­ni­za­tion of the United Na­tions (FAO) in Rome is­sued alerts about the three dis­eases on Fe­bru­ary 3, 2017. Rust re­turned to Europe with a big out­break in Si­cily in 2016, even the hardy du­rum wheat, used to make pasta, was found to be sus­cep­ti­ble to it.

Sci­en­tists from In­dian Coun­cil of Agri­cul­tural Re­search (ICAR) in col­lab­o­ra­tion with agri­cul­tural uni­ver­si­ties have cre­ated a his­tory by eval­u­at­ing the en­tire wheat germplasm col­lec­tion (~20,000 ac­ces­sions) con­served in the In­dian Na­tional Genebank at ICARNa­tional Bureaux of Plant Ge­netic Re­sources, New Delhi. The find­ings of the study au­thored by 37 con­trib­u­tors have been pub­lished in ‘PLOS ONE.’ The re­sults are of great prac­ti­cal sig­nif­i­cance keep­ing in view the con­tin­u­ous search of genes for breed­ing mul­ti­ple rusts re­sis­tant wheat va­ri­eties. This is the first such well thought of ex­per­i­ment con­ducted ever on genebank col­lec­tions of this mag­ni­tude.

The study on eval­u­a­tion dis­cov­ered novel wheat germplasm re­sources car­ry­ing genes for re­sis­tance to all rusts and spot blotch dis­eases. 19,460 wheat ac­ces­sions com­pris­ing three species of wheat - Triticum aes­tivum, T. du­rum and T. dic­oc­cum and col­lected from within and out­side the coun­try were screened dur­ing the 201114 crop seasons se­quen­tially at mul­ti­ple dis­ease hotspots, viz. Welling­ton (Tamil Nadu) for wheat rusts, Gur­daspur (Pun­jab) for stripe rust and Cooch Be­har (West Ben­gal) for spot blotch. This led to short­list­ing of po­ten­tially re­sis­tant ac­ces­sions to mul­ti­ple rusts (498 accs.) and spot blotch (868 accs.).

Test­ing of the se­lected ac­ces­sions for seedling re­sis­tance against seven vir­u­lent patho­types (col­lected since 1930) of three wheat rusts un­der ar­ti­fi­cial epi­phy­totic con­di­tions at Flow­erdale, Shimla led to the iden­ti­fi­ca­tion of 137 ac­ces­sions po­ten­tially re­sis­tant to mul­ti­ple rusts. Molec­u­lar anal­y­sis added fur­ther value to the study and helped iden­tify dif­fer­ent com­bi­na­tions of ge­netic loci im­part­ing re­sis­tance to leaf rust, stem rust, stripe rust and spot blotch.

The re­sis­tant germplasm ac­ces­sions, par­tic­u­larly against stripe rust, iden­ti­fied in this study can act as po­ten­tial re­sources for in­te­grat­ing mul­ti­ple dis­ease re­sis­tance into the ge­netic back­ground of high yield­ing wheat cul­ti­vars through con­ven­tional or molec­u­lar breed­ing ap­proaches, thus en­sur­ing food se­cu­rity at na­tional and global lev­els.

An­other ma­jor sci­en­tific break­through of ICAR led to the de­cod­ing of genomes of 15 strains of wheat rust fun­gus Puc­cinia trit­ic­ina.

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