Improving Stripe Rust Resistance And Agronomic Performance In Three Elite Wheat Cultivars Using A Combination Of Phenotypic Selection And Marker Detection Of Yr48

Stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is a fungal disease that significantly devastates wheat production worldwide. This disease is most effectively restrained by developing and deploying wheat cultivars with highly durable resistance. One adult plant resistance (APR) gene, Yr48, was validated and introgressed from germplasm PI 610750 into three Chinese elite wheat cultivars: Chuanmai 42 (CM42), Lunxuan 987 (LX987), and Bainongaikang 58 (BNAK58), using marker-assisted selection. The three Chinese elite cultivars, as the recipient parents, were used to cross with the donor parent PI 610750. Eighty-seven introgression lines (ILs) were gained from all three cross populations in the F5 generation through phenotypic selection. To validate the ILs possessing Yr48 in the 87 selected lines, linked SSR markers were used to detect its presence or absence in different genetic backgrounds. The 87 ILs from the three crosses were also evaluated for agronomic traits following stringent phenotypic criteria. Field evaluation and genotypic results identified 33 ILs with improved stripe rust resistance. Phenotypic investigation of 33 promising ILs showed that nine lines had better desirable agronomic traits. These ILs had more high-level resistance to stripe rust (infection type range 2-4, disease severity of 5-35%) as well as increased thousand-grain weight (4.5-31.1%), productive till number (25-75%), spike length (9.1-42.5%), grain number (7-51.6%), and appropriate plant height in infested environments compared to the recipient parents. Based on the improved stripe rust resistance and agronomic performance, the selected lines can be further evaluated and promoted as candidate varieties. This study serves as a demonstration of utilizing conventional breeding and molecular marker-assisted selection to improve elite wheat cultivars.