Fine mapping and transferring wheat adult-plant powdery mildew resistance gene Pm62 through T2DS·2VL translocations

The wheat adult-plant powdery mildew resistance gene Pm62 was introgressed through a T2DS·2VL translocation, fine-mapped to a narrowed region on chromosome 2VL, and its impact on yield-related traits was characterized. Powdery mildew, caused by Blumeria graminis f. sp. tritici (Bgt), threatens global wheat production. Adult‑plant resistance (APR) genes from wheat relatives remain crucial for its control. The APR gene Pm62 was previously introduced into wheat via the T2BS·2 V#5L translocation from Dasypyrum villosum, while the susceptible T2DS·2 V#4L line NAU198 was also created. Here, we developed a Pm62-harboring T2DS·2 V#5L translocation line, NAU197, from DS2V#5(2D)/NAU0686 progeny and verified its chromosomal constitution using molecular cytogenetic approaches. Inoculation with Bgt isolate E09 demonstrated that both NAU197 and NAU198 were susceptible at the three-leaf stage; however, NAU197 displayed significant resistance after the five-leaf stage and achieved full resistance during elongation. Genetic analysis of NAU197/NAU198 F₁ and F₂ populations confirmed that Pm62 functions as a single dominant gene. Using 37 polymorphic markers on the 2VL arm, we mapped Pm62 in 233 F₂ plants to an interval flanked by InDel markers F30 (0.08 cM) and F79 (0.04 cM). Further screening of 2733 F₂ plants identified 11 recombinants within Pm62 interval, and eight newly developed markers delimited Pm62 to a ~ 0.6 Mb region between F86 and F108 in the D. villosum 91C43^DH reference genome. This region contains nine high‑confidence protein‑coding genes and five uncharacterized proteins, among which two C2‑domain genes and two chitinase genes are prime candidates. The new T2DS·2 V#5L translocation in wheat background NMZ167 showed no yield penalty. Our results establish an effective strategy for genetic mapping of alien genes and provide a valuable genetic resource and molecular tool for wheat breeding focused on disease resistance.