Identification of genomic regions involved in resistance against Sclerotinia sclerotiorum from wild Brassica oleracea

Abstract

The lack of resistant source has greatly restrained resistance breeding of rapeseed (Brassica napus, AACC) against Sclerotinia sclerotiorum which causes severe yield losses in rapeseed production all over the world. Recently, several wild Brassica oleracea accessions (CC) with high level of resistance have been identified (Mei et al. in Euphytica 177:393-400, 2011), bringing a new hope to improve Sclerotinia resistance of rapeseed. To map quantitative trait loci (QTL) for Sclerotinia resistance from wild B. oleracea, an F2 population consisting of 149 genotypes, with several clones of each genotypes, was developed from one F1 individual derived from the cross between a resistant accession of wild B. oleracea (B. incana) and a susceptible accession of cultivated B. oleracea var. alboglabra. The F2 population was evaluated for Sclerotinia reaction in 2009 and 2010 under controlled condition. Significant differences among genotypes and high heritability for leaf and stem reaction indicated that genetic components accounted for a large portion of the phenotypic variance. A total of 12 QTL for leaf resistance and six QTL for stem resistance were identified in 2 years, each explaining 2.2-28.4 % of the phenotypic variation. The combined effect of alleles from wild B. oleracea reduced the relative susceptibility by 22.5 % in leaves and 15 % in stems on average over 2 years. A 12.8-cM genetic region on chromosome C09 of B. oleracea consisting of two major QTL intervals for both leaf and stem resistance was assigned into a 2.7-Mb genomic region on chromosome A09 of B. rapa, harboring about 30 putative resistance-related genes. Significant negative corrections were found between flowering time and relative susceptibility of leaf and stem. The association of flowering time with Sclerotinia resistance is discussed.

Identification of QTLs for Resistance to Sclerotinia Stem Rot and BnaC.IGMT5.a as a Candidate Gene of the Major Resistant QTL SRC6 in Brassica napus

“…The fact that QTLs for the resistance on C6 can be repeatedly mapped suggests the importance of genetic components from B. oleracea (C-genome) for S. sclerotiorum . This is also consistent with recent studies which found several QTLs in C-genome [47], [48]. Further fine mapping and eventually cloning of SRC6 identified in this research will offer novel information for understanding the resistance mechanism and provide valuable resources for Sclerotinia -resistant breeding, since immune or highly resistant germplasms are not available in B. napus and its close relatives.…”

Detecting the Hormonal Pathways in Oilseed Rape behind Induced Systemic Resistance by Trichoderma harzianum TH12 to Sclerotinia sclerotiorum

“…sclerotiorum [2], B . napus ‘Charlton’ cultivar [34, 35] and Brassica oleracea [37] as well as the hexaploid B . napus (AACCCC), derived from crosses between ‘Zhongshuang 9’ and B .…”

New sources of resistance to Sclerotinia sclerotiorum for crucifer crops

“…Further, Zhang et al (2011) demonstrated QTL linked to SR resistance in B. napus, either at seedling or adult plant stages, and while QTL qSRS1, qSRS9, qSRM3 and qSRM9 had a positive effect towards SR resistance, only qSRS9 at the seedling stage and qSRM9 at the adult stage were at the same position on linkage group N9. Mei et al (2013) also concluded that the genetic control of leaf and stem resistance are probably different. The involvement of so many QTL suggests that there may be diverse mechanisms by which brassicas resist invasion by S. sclerotiorum, and the results of our study support the emerging certainty for different mechanisms for resistance in leaves and stems.…”