Abstract
In this study, we successfully introgressed and validated Yr59 into four elite wheat cultivars, Jimai 22, Chuanmai 42, Zhengmai 9023 and Xinmai 26 through marker-assisted backcross selection. Used as female parents, these four cultivars were crossed with wheat line PI 660061 (Yr59). After two backcrosses and marker-assisted selection, the progenies were selfed and advanced to the BC2F4 generation. A total of 123 BC2F4 lines were selected based on agronomic traits and stripe rust resistance, and their BC2F5 and BC2F6 progenies were further evaluated for stripe rust resistance and agronomic traits. Seven markers linked with relevant genes, including Xbarc32, Xwgp5175, Xwmc557 and Xcfa2040 linked with Yr59; Xwmc658 with YrJ22; WE173 and Xbarc181 with Yr26, were used to genotype the breeding lines. A total of 109 introgression lines with positive markers for Yr59 were identified for further stripe rust and agronomic trait evaluation. Finally, 16 lines had higher levels resistance to stripe rust, and similar or superior agronomic traits compared to their parents were obtained. These lines can be released as new cultivars for various regions after regional tests and also can be used as resistance stocks for regional breeding programs to develop new cultivars with adequate and durable resistance to stripe rust.
Highlights
Zhengmai 9023 (ZM9023), a weak spring cultivar developed by Wheat Research Institute of Henan Academy of Agricultural Sciences, has high salt tolerance, superior gluten quality and Fusarium head blight resistance (QFhb.7D) [52,53]; it was extensively planted in Henan and other provinces
PI 660061, a wheat germplasm line transferred from PI 178759, has excellent resistance to stripe rust and relatively better agronomic traits compared to PI 178759 [56] and was used as the donor parent of Yr59 in crosses with the four Chinese cultivars
Thirty three true F1 plants were identified to contain positive Xbarc32, consisting of eight from Chuanmai 42 (CM42)/PI660061, nine from Jimai 22 (JM22)/PI660061, seven from ZM9023/PI660061 and nine from Xinmai 26 (XM26)/PI660061. These true F1 plants were used as male parents to make the first-round backcross with their recurrent parents CM42, JM22, ZM9023 or XM26
Summary
Wheat is one of the most widely cultivated cereal crops in the world and a staple food for approximately 40% of the world’s populations, providing over 20% of the calories, 25% of the protein and nearly 55% of the carbohydrate intake of humans [1]. Wheat cultivars with high yield and high quality are crucial for global food safety. Certain biotic and abiotic stresses limit the realization of the full genetic potential of modern wheat cultivars, of which stripe rust, caused by Puccinia striiformis Westend. It is reported that the grain yield and quality loss of resistant wheat varieties were less than that of the susceptible under wheat stripe rust infection environment [4]. Fungicides can be used to reduce yield losses caused by stripe rust, but the use of fungicides adds cost to production and may be harmful to the users and the environment. The best approach of stripe rust control is breeding stripe rust-resistant cultivars
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