Marker assisted breeding for rust resistance in lodging tolerant mutant and meta analysis for identification of breeders qtls for multiple rust resistance in hexaploid wheat Triticum aestivum l

Abstract

Rust diseases in wheat are a major threat to global food security. Therefore, development newlineof multiple disease-resistant cultivars (resistant to all three rusts) is a major goal in all wheat newlinebreeding programs worldwide. In view of this initially, a marker assisted backcrossing was newlineperformed to transfer two highly effective stripe rust resistance genes (Yr10 and Yr15) into a newlinelodging resistant mutant wheat (PMW-2016-1) developed from a hexaploid wheat cultivar DPW newline621-50 (PBW 621 and DBW 50) (KAUZ//ALTAR84/AOS/3/MILAN/KAUZ/4/HUITES). For newlinethis, the two wheat cultivars Avocet-Yr10 carrying stripe rust resistance gene Yr10 and Avocet- newlineYr15 carrying stripe rust resistance gene Yr15 were used as donors for stripe rust. Two of the SSR newlinemarkers Xpsp3000 and Xbarc8 linked to the stripe rust resistant genes Yr10 and Yr15 were used newlinefor marker assisted foreground selection to select plants carrying Yr10 and Yr15 gene(s). A total of newline210 SSR markers covering all the 21 chromosomes were selected to isolate the polymorphic newlinemarkers for background selection of the recurrent parent. Further, the SSR markers which were newlinefound polymorphic were used for the background selection in selected lines after foreground newlineselection for Yr10 and Yr15 genes. Foreground selection coupled with background selection was newlinealso followed by phenotypic selection to identify the plants homozygous for stripe rust and agromorphological newlinetraits to recurrent parent (PMW-2016-1). The selected lines were attributed to agromorphological newlinetraits like: days to heading, days to anthesis, plant height, number of tillers, spike newlinelength and spikelets per spike, grain number per spike, thousand grain weight, yield per plant and newlinestem strength. The material was then advanced up to BC3F2 generation. Findings of this newlineinvestigation showed the usefulness of marker assisted selection in precise transfer of the genes for newlinestripe rust resistance combined with phenotypic selection to recover yield and its components traits newlineto develop an improved version of PMW-2016-1. Additionally, the present study also included the newlineidentification of meta-QTLs and candidate genes for multiple disease resistance (MDR) involving newlineall three rusts. In this investigation a total of 152 individual QTL mapping studies for resistance to newlineleaf rust (LR), stem rust (SR), and yellow rust (YR) were used. From these 152 studies, a total of newline1,146 QTLs for resistance to three rusts were retrieved, which included 368 QTLs for LR, 291 newlineQTLs for SR, and 487 QTLs for YR. Of these 1,146 QTLs, only 718 QTLs could be projected newlineonto the consensus map saturated with 2, 34,619 markers. Meta-analysis of the projected QTLs newlineresulted in the identification of 86 MQTLs, which included 71 MDR-MQTLs. Ten of these newlineMDR-MQTLs were referred to as the Breeders MQTLs . Seventy-eight of the 86 MQTLs could newlinealso be anchored to the physical map of the wheat genome and 54 MQTLs were validated by newlinemarker-trait associations identified during earlier genome-wide association studies. Twenty newlineMQTLs (including 17 MDR-MQTLs) identified in the present study were also co-localized with newline44 known R genes. In silico expression analysis allowed identification of several differentially newlineexpressed candidate genes (CGs) encoding proteins carrying different domains including the newlinefollowing: NBS-LRR, WRKY domains, F-box domains, sugar transporters, transferases, etc. The newlineintrogression of these MDR loci into high-yielding cultivars should prove useful for developing newlinehigh yielding cultivars with resistance to all the three rusts.