Wheat stripe rust is one of the most destructive diseases to affect wheat. Although the major resistant wheat varieties have made a great contribution to global food security, yield losses from stripe rust still occur in large wheat growing areas when climatic conditions are unstable. Despite this threat, resistance levels and yield losses of these elite wheat cultivars under wheat stripe rust infection have not been well studied. Based on this investigation of natural infection conditions over 2 years, analysis of the area-under-the-disease-progress-curves differentiated the susceptible cultivars Mianmai 367 (MM367; 788.59), Jinmai 47 (JM47; 1,087.71), and Avocet Susceptible (AvS; 1,314.59) from resistant cultivars Xikemai 18 (XKM18; 177.50) and Xiaoyan 6 (XY6; 545.67). Stripe rust resulted in a 2-year mean yield loss of 32% for all tested varieties. The susceptible varieties JM47, AvS, and MM367 lost 64, 55, and 21% of grain yield, respectively. On the contrary, rust-resistant cultivars XKM18 and XY6 lost only 11 and 28%, respectively. In addition, stripe rust resulted in reduced kernel hardness, flour yield, and flour whiteness. Dough and gluten properties were also affected. Overall, results revealed that the grain yield and quality loss values of the resistant wheat cultivars were less than in the susceptible cultivars. Disease-resistant cultivars such as XKM18 should be promoted and recommended for application. It may also be suggested that growing a susceptible variety such as MM367 could be feasible in combination with fungicide application under high disease pressure.

Stripe rust is a foliar disease in wheat caused by Puccinia striiformis f. tritici. The best way to protect wheat from this disease is by growing resistant cultivars. Tetraploid wheat can serve as a good source of valuable genetic diversity for various traits. Here, we report the mapping of nine stripe rust resistance quantitative trait loci (QTL) effective against P. striiformis f. tritici in China and Israel. We used recombinant inbred lines (RILs) developed from a cross between the durum wheat cultivar Svevo and Triticum dicoccoides accession Zavitan. By genotyping the RIL population of 137 lines using the wheat 90K single-nucleotide polymorphism array, we mapped an adult-plant resistance locus QYrsv.swust-1BL.1, the most effective QTL, within a 0.75-centimorgan region in T. turgidum subsp. durum ‘Svevo’ on chromosome arm 1BL, corresponding to the region of 670.7 to 671.5 Mb on the Chinese Spring chromosome arm 1BL. Of the other eight minor-effect stripe rust QTL, seven were from Svevo and mapped on chromosomes 1A, 1B, 2B, 3A, 4A, and 5A, and one was from Zavitan and mapped on chromosome 2A. Several QTL with epistatic effects were identified as well. The markers linked to the resistance QTL can be useful in marker-assisted selection for incorporation of these resistance QTL into both durum and common wheat cultivars.

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.

Wheat stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is one of the most devastating diseases in wheat. Due to the large-scale and widely-distributed planting pattern of wheat, the directional selection pressure of the pathogen is very strong. Therefore, it is urgent to pyramid more stripe rust resistance genes in wheat cultivars to enhance resistance durability and ensure wheat production safety. In this study, two quantitative trait loci (QTL) for adult plant resistance (APR) to stripe rust, QYr.nafu-2BL and QYr.nafu-3BS, were validated and introgressed from wheat line P9897 into three Chinese elite wheat cultivars, Chuanmai 42, Xiangmai 25, and Zhengmai 9023, through marker validation. The three Chinese elite varieties were used as the female parent to cross with wheat line P9897, and they were selfed to the F6 generation. A total of 114 lines were then selected based on field agronomic traits and stripe rust resistance. Four markers (Xcfd73, Xgwm120, Xbarc87 and Xbarc133) linked with the QTL’s regions were employed to screen the 114 F6 lines. Subsequently, 27 lines combining two target QTL from P9897 were selected. The combination of agronomic traits and disease resistance results showed that 13 of these selected lines had favorable application prospects. The promising lines selected in this study could enrich the genetic resources of wheat stripe rust resistance genes, as well as provide material support and a theoretical basis for the prevention and control of wheat stripe rust in China.

Wheat gene Yr39 confers durable high-temperature adult-plant (HTAP) resistance to stripe rust caused by Puccinia striiformis f. sp. tritici, one of the most destructive diseases of wheat worldwide. The objective of this study was to transfer Yr39 into four Chinese elite wheat cultivars. Backcross inbred line populations were developed from four Chinese wheat cultivars Chuanmai 42 (CM42), Bainong Aikang 58 (AK58), Han 6172 (H6172) and Zhengmai 9023 (ZM9023) crossed with a Yr39 single-gene line. The F₁, BC₁F₁ and BC₁F₆ lines were genotyped using resistance gene analogs polymorphism (RGAP) markers Xwgp36, Xwgp44 and Xwgp43, which are closely linked to Yr39. Progeny lines selected with the markers for Yr39 were evaluated in the field for stripe rust resistance and agronomic traits including plant height, tiller numbers, spike grain numbers and thousand-grain weight. Eleven lines were selected with stripe rust resistance and desirable agronomic traits. These lines with production potential can be used for further testing in various wheat production regions and as germplasm resources for breeding new wheat cultivars with durable stripe rust resistance, high yield, and adaptation to different production environments.