ARS | Publication request: MOLECULAR CHARACTERIZATION OF SLOW LEAF RUSTING RESISTANCE IN WHEAT

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 1, 2004
Publication Date: February 23, 2005
Citation: Xu, X., Bai, G., Carver, B.F., Shaner, G.E., Hunger, R.M. 2005. Molecular characterization of slow leaf rusting resistance in wheat. Crop Science. 45:758-765.

Interpretive Summary: Leaf rust in wheat is an important disease in US. It occurs in almost all wheat fields in the US and cause significant yield losses every year. Due to rapid change of pathogen races, single gene resistance is short-lived in wheat cultivars. Slow leaf rusting resistance is a desireable type of resistance because it does not lose its effectiveness when new pathogen races occur. Although this type of resistance does not provide full protection against rust infection, it can slow down the disease infection rate and minimize the losses caused by rust infection. Wheat cultivar CI 13227 with slow rusting resistance was characterized with molecular markers. Two chromosome regions (2B and 7BL) were consistently associated with 3 components of leaf rust (final severity (FS), area under disease progress curve (AUDPC), infection rate (IR)). The third chromosome region (2DS) associates with leaf rust infection duration. Several molecular markers associated with slow rusting resistance in the three chromosome regions identified in this study have potential to be used in marker-assisted breeding for durable leaf rust resistant cultivars.

Technical Abstract: Slow leaf rusting resistance in wheat (Triticum aestivum L) is gaining acceptance as a breeding objective due to its durability in comparison with race-specific resistance. CI 13227 was previously reported to provide the highest level of slow leaf rusting resistance. The objective of this study was to characterize the slow leaf rusting resistance conferred by CI 13227 using molecular markers. A population of recombinant inbred lines (RILs) derived from CI 13227 / Suwon 92 was evaluated for final severity (FS), area under disease progress curve (AUDPC), infection rate (IR), and infection duration (ID) of leaf rust. Four hundred fifty nine AFLP markers and 19 SSR markers were analyzed in the population. Two quantitative trait loci (QTL), designated as QLr.osu-2B and QLr.osu-7BL, were consistently associated with AUDPC, FS, and IR of leaf rust. The percentages of phenotypic variance explained by each QTL varied with experiments and traits, ranging from 13.4% to 18.8% for AUDPC, 12.5% to 20.8% for FS, and 12.9% to 16.1% for IR. The third QTL for leaf rust ID, designated as QLrid.osu-2DS, was located on chromosome 2DS and explained 26.4% and 21.47% of the phenotypic variance in 1994 and 1995, respectively. Both the QTL and correlation analysis indicate reasonable progress in leaf rusting resistance by selecting for final severity. SSR markers closely associated with QLr.osu-2B or QLr.osu-7BL have potential to be used in marker-assisted selection for durable leaf rust resistant cultivars.