ARS | Publication request: Lesion Mimic Associates with Adult Plant Resistance to Leaf Rust Infection in Wheat

Submitted to: Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 8, 2009
Publication Date: March 28, 2009
Citation: Li, T., Bai, G. 2009. Lesion Mimic Associates with Adult Plant Resistance to Leaf Rust Infection in Wheat. Theoretical and Applied Genetics. 119:13-21.

Interpretive Summary: Lesion mimics (LM) in wheat are yellowish spots that look similar to plant disease symptoms but without attack from plant pathogens. LM has been reported in many other plant species and demonstrated to increase plant disease resistance to many pathogens. Wheat line Ning7840 has adult plant resistance (APR) to leaf rust (Puccinia triticina) and shows LM symptoms. We identified a LM gene (lm) in Ning7840 and located it on chromosome 1BL. The data showed that the lines with LM had a higher rust resistance than the non-LM lines. Molecular mapping identified a gene named Qlr.pser.1BL for rust resistance on chromosome 1BL. Qlr.pser.1BL and lm gene were located at the same chromosome location and showed major effects on leaf rust resistance in two greenhouse experiments, therefore lm from Ning7840 may have significant effects on adult plant resistance to leaf rust.

Technical Abstract: Lesion mimics (LM) that resemble plant disease symptoms in the absence of plant pathogens may confer enhanced plant disease resistance to a wide range of pathogens. Wheat line Ning7840 has adult plant resistance (APR) to leaf rust (Puccinia triticina) and shows LM symptoms at heading. A recessive gene (lm) was found to be responsible for LM in Ning7840 and located near the proximal region of chromosome 1BL using a population of 179 recombinant inbred lines (RIL) derived from the cross Ning7840/Chokwang. Genomic in situ hybridization (GISH) showed that Ning7840 carries the short arm of 1R chromosome from rye (Secale cereale L.), on which the race-specific gene Lr26 resides. The RILs were infected with the isolate PRTUS55, an isolate virulent to Lr26, at anthesis in two greenhouse experiments. The result showed that the lines with LM phenotype had a significantly higher rust resistance than the non-LM lines. Composite interval mapping consistently detected a QTL, Qlr.pser.1BL, for APR on chromosome 1BL. Qlr.pser.1BL peaked at lm and explained up to 60.8% of phenotypic variation for leaf rust resistance in two greenhouse experiments therefore lm from Ning7840 may have pleiotropic effects on APR to leaf rust.