Genome-Wide Identification of QTLs Conferring High-Temperature Adult-Plant (HTAP) Resistance to Stripe Rust (Puccinia striiformis f. sp. tritici) In Wheat.

High-temperature adult-plant (HTAP) resistance to stripe rust (Puccinia striiformis f. sp. tritici) is a durable type of resistance in wheat. The objective of this study was to identify quantitative trait loci (QTL) conferring HTAP resistance to stripe rust in a population consisted of 169 F_8:10 recombinant inbred lines (RILs) derived from a cross between a susceptible cultivar ‘Rio Blanco’ and a resistant germplasm IDO444. HTAP resistance was evaluated for both disease severity and infection type under natural infection over two years at two locations. The genetic linkage maps covering almost the whole genome with an average density of 6.7 cM per marker were constructed by using 484 markers including 96 SSRs, 384 DArTs, two STSs from dwarf genes Rht1 and Rht2 and another two markers for low-molecular-weight glutenin subunit of seed storage protein. QTL analysis detected a total of eight QTLs significantly associated with HTAP resistance to stripe rust with two on chromosome 2B, two on 3B and one on each of 1A, 4A, 4B and 5B. QTLs on chromosomes 2B and 4A were the major loci derived from IDO444 and explained up to 47% and 42% of the phenotypic variation, respectively. The remaining five QTLs have the relative smaller effects with each accounted only about 7 to 10% of the trait variation and were detected in part of the data sets. Of these minor QTLs, QYrrb.uid-3B.1 and QYrrb.uid-4B were both contributed by Rio Blanco and were both associated with infection type only. The remaining three QTLs, QYrid.uid-1A, QYrid.uid-3B.2 and QYrid.uid-5B, were all conditioned by IDO444 and associated with either infection type or disease severity. These three QTLs were previously undetected and thus may be novel loci of conferring HTAP resistance. Markers linked to 2B and 4A QTLs were potentially to be used for improving HTAP resistance to stripe rust.