Mapping of Quantitative Trait Loci for Leaf Rust Resistance in the Wheat Population Xinmai 26 ⨯Zhoumai 22.

Leaf rust, caused by the fungal pathogen Puccinia triticina (Pt), is one of the major and dangerous diseases of wheat and has caused serious yield loss of wheat worldwide. Here, we investigated leaf rust adult-plant resistance (APR) in a recombinant inbred line (RIL) population derived from Xinmai 26 and Zhoumai 22 over three years. Linkage mapping for APR to leaf rust revealed four QTL in this RIL population. Two QTL QLr.hnau-2BS and QLr.hnau-3BS were contributed by Zhoumai22, whereas QLr.hnau-2DS and QLr.hnau-5AL were contributed by Xinmai 26. The QLr.hnau-2BS covering a race-specific resistance gene Lr13 showed the most stable leaf rust APR. Overexpression of Lr13 significantly increases leaf rust APR. Interestingly, we found that a CNL-like gene named as TaCN in the QLr.hnau-2BS was completely co-segregated with leaf rust resistance. The resistance haplotype TaCN-R possessed half sequence of the coiled-coil domain of TaCN protein. The Lr13 strongly interacted with TaCN-R, but not interacted with the full-length TaCN (TaCN-S). In addition, TaCN-R was significantly induced after Pt inoculation and changed the subcellular localization of Lr13 after interaction. Therefore, we hypothesized that TaCN-R mediated leaf rust resistance possibly by interacting with Lr13. This study provided important QTL for APR to leaf rust and a new insight into understanding of NBS-LRR gene modulating disease resistance in common wheat.