Quantitative trait loci for partial resistance to Aphanomyces root rot in pea

Abstract

Aphanomyces root rot, caused by Aphanomyces euteiches Drechs, is the most-important disease of pea ( Pisum sativum L.) worldwide. No efficient chemicals are available to control the pathogen. To facilitate breeding for Aphanomyces root rot resistance and to better understand the inheritance of partial resistance, our goal was to identify QTLs associated with field partial resistance. A population of 127 RILs from the cross Puget (susceptible) x 90-2079 (partially resistant) was used. The lines were assessed for resistance to A. euteiches under field conditions at two locations in the United States (Pullman, Wash. and LeSueur, Minn.) in 1996 and 1998 for three criteria based on symptom intensity and disease effects on the whole plant. The RILs were genotyped using automated AFLPs, RAPDs, SSRs, ISSRs, STSs, isozymes and morphological markers. The resulting genetic map consisted of 324 linked markers distributed over 13 linkage groups covering 1,094 cM (Kosambi). Twenty seven markers were anchored to other published pea genetic maps. A total of seven genomic regions were associated with Aphanomyces root rot resistance. The first one, located on LG IVb and named Aph1, was considered as "major" since it was highly consistent over the years, locations and resistance criteria studied, and it explained up to 47% of the variation in the 1998 Minnesota trial. Two other year-specific QTLs, namely Aph2 and Aph3, were revealed from different scoring criteria on LG V and Ia, respectively. Aph2 and Aph3 mapped near the r (wrinkled/round seeds) and af (normal/afila leaves) genes, and accounted for up to 32% and 11% of the variation, respectively. Four other "minor" QTLs, identified on LG Ib, VII and B, were specific to one environment and one resistance criterion. The resistance alleles of Aph3 and the two "minor" QTLs on LG Ib were derived from the susceptible parent. Flanking markers for the major Aphanomyces resistance QTL, Aph1, have been identified for use in marker-assisted selection to improve breeding efficiency.

Genetic characterization of pea (Pisum sativum) germplasm from Turkey using morphological and SSR markers

“…However, few studies have used SSR markers (Weeden et al,1998;Burstin et al, 2001;Pilet-Nayel et al, 2002;Baranger et al, 2004;Prioul et al, 2004;Tar'an et al, 2005;Zong et al, 2008a,b). SSR markers were reported as superior in terms of high information content and discrimination power owing to high allelic variation, allowing clear identification of all varieties compared to most DNA as well as biochemical and morphological markers (Smýkal et al, 2008).…”

Genotypic population structure of Ascochyta pinodes and Phoma pinodella in Poland

“…These stud ies in clude also map ping the ge nome of host or the ge nome of patho gens in order to find QTLs loci con fer ring re sis tance or con fer ring ag gres sive ness or vir u lence and toxin syn the sis (Barranger et al 2006, Bretag et al 1995, Cubero et al 2005, Cho et al 2004, Fondevilla et al 2006, Ford et al 1999, 1991, 1992, Kraft et al 1998, Kraft and Pfleger 2001, Marcinkowska 1996, Marcinkowska and Witkowska 1996, Pilet-Nayel et al 2002, Santra et al 2000, 2001, Prioul et al 2004, Timmerman -Vaughan et al 2000, Wroth 1999, Xue and Warkentin 2001.…”

Recent Advances in QTL Mapping and Quantitative Disease Resistance Approach

“…>10%) and minor QTLs will usually account for <10%. Sometimes, major QTLs may refer to QTLs that are stable across environments whereas minor QTLs may refer to QTLs that may be environmentally sensitive, especially for QTLs that are associated with disease resistance (Li et al, 2001;Lindhout, 2002;Pilet-Nayel et al, 2002). In more formal terms, QTLs may be classified as: (1) suggestive; (2) significant; and (3) highly significant (Lander and Kruglyak, 1995).…”