# Identification and Mapping of QTLs for Adult Plant Resistance in Wheat Line XK502

## TL;DR

This study identifies five genetic regions in wheat that help resist stripe rust, a major disease, and finds three of them may contain new resistance genes.

## Contribution

The study maps five QTLs for adult plant resistance in wheat, three of which may contain previously unidentified resistance genes.

## Key findings

- Five QTLs for stripe rust resistance were identified in wheat line XK502, explaining 5.67–36.74% of phenotypic variation.
- Three of the QTLs may contain new, unidentified resistance genes based on their locations.
- Sixteen RILs with strong stripe rust resistance and good agronomic traits were selected for breeding programs.

## Abstract

Stripe rust is a serious wheat disease occurring worldwide. At present, the most effective way to control it is to grow resistant cultivars. In this study, a population of 221 recombinant inbred lines (RILs) derived via single-seed descent from a hybrid of a susceptible wheat line, SY95-71, and a resistant line, XK502, was tested in three crop seasons from 2022 to 2024 in five environments. A genetic linkage map was constructed using 12,577 single-nucleotide polymorphisms (SNPs). Based on the phenotypic data of infection severity and the linkage map, five quantitative trait loci (QTL) for adult plant resistance (APR) were detected using the inclusive composite interval mapping (ICIM) method. These five loci are QYrxk502.swust-1BL, QYrxk502.swust-2BL, QYrxk502.swust-3AS, QYrxk502.swust-3BS, and QYrxk502.swust-7BS, explaining 5.67–19.64%, 9.63–36.74%, 9.58–11.30%, 9.76–23.98%, and 8.02–12.41% of the phenotypic variation, respectively. All these QTL originated from the resistant parent XK502. By comparison with the locations of known stripe rust resistance genes, three of the detected QTL, QYrxk502.swust-3AS, QYrxk502.swust-3BS, and QYrxk502.swust-7BS, may harbor new, unidentified genes. From among the tested RILs, 16 lines were selected with good field stripe rust resistance and acceptable agronomic traits for inclusion in breeding programs.