Genotyping alien introgression lines of Brassica juncea (L.) Coss. and mapping of gene(s) for resistance to Sclerotinia sclerotiorum (Lib.) de Bary
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Date
2016
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Punjab Agricultural University, Ludhiana
Abstract
Two sets of Brassica juncea introgression lines (ILs) carrying introgressed chromosome
fragments from two wild Brassicaceae species, Brassica fruticulosa and Erucastrum
cardaminoides were investigated for their resistance responses to stem from inoculation with
Sclerotinia sclerotiorum, the world wide pathogen of crop brassicas. Molecular characterization
of ILs was also undertaken using SSR and candidate gene based markers. The percentage of
donor genome in the B. juncea-B. fruticulosa ILs varied from 2.1 (IL-283) to 30.2% (IL-248). A
total of 22 significant marker trait associations were detected across two crop seasons. Of these,
14 marker loci were A-genome specific; eight were B-genome specific. Five were common
across the seasons. Significantly associated markers were SB4817, SJ4933, SJ3640I, SJ0644,
SB1871, nia-m043, nia-m138, cnu-m482, cnu-m298, cnu-m245 and cnu-m254. These
introgression lines were also genotyped using 60 gene-specific markers developed from the
sequence information of the candidate genes associated with resistance to Sclerotinia stem rot.
Five significant marker trait associations (MTAs) were identified. Out of these, MTA involving
ABI2-1 was consistent across the seasons and the pooled data. The phenotypic variance
explained ranged from 21-30 percent. MTAs involving ABI1-3_1, also steady over seasons,
accounted for 14 to 26 percent of the phenotypic variation. A second set of 96 B. juncea- E.
cardaminoides introgression lines (ILs) were also genotyped with SSR markers and phenotyped
for their resistance to Sclerotinia stem rot as well. Association mapping allowed the
identification of six marker loci (based on A genome markers) influencing the resistance to
Sclerotinia stem rot resistance. Of these, three were detected in both seasons as well as pooled
data. In case of B genome based markers, six associations were observed in season I, 5 in S II
and 5 in pooled over both seasons. These studies not only provided important new insights into
the introgressed resistance but also opens the way for novel engineering of new B. juncea
varieties that express this key resistance to this worldwide devastating pathogen of mustard
crops
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Keywords
Alien introgression, B. fruticulosa, Erucastrum cardaminoides, marker trait associations, Brassica juncea, Sclerotinia sclerotiorum