Abstract
The genetic basis of seed germination and seedling vigor is largely unknown in Brassica species. We performed a study to evaluate the genetic basis of these important traits in a B. rapa doubled haploid population from a cross of a yellow-seeded oil-type yellow sarson and a black-seeded vegetable-type pak choi. We identified 26 QTL regions across all 10 linkage groups for traits related to seed weight, seed germination and seedling vigor under non-stress and salt stress conditions illustrating the polygenic nature of these traits. QTLs for multiple traits co-localized and we identified eight hotspots for quantitative trait loci (QTL) of seed weight, seed germination, and root and shoot lengths. A QTL hotspot for seed germination on A02 mapped at the B. rapa Flowering Locus C (BrFLC2). Another hotspot on A05 with salt stress specific QTLs co-located with the B. rapa Fatty acid desaturase 2 (BrFAD2) locus. Epistatic interactions were observed between QTL hotspots for seed germination on A02 and A10 and with a salt tolerance QTL on A05. These results contribute to the understanding of the genetics of seed quality and seeding vigor in B. rapa and can offer tools for Brassica breeding.
Highlights
Brassica rapa (A genome, 2n = 20) consists of several economically important morphotypes, such as leafy vegetables, oilseed types and turnips, with huge morphological and genetic diversity
Pearson correlation coefficients of the same parameter were higher between two seed batches than between stress levels (Supplementary Figure S1)
Thousandseed weight was positively correlated with AUC (r = 0.25 to 0.37) and Gmax (r = 0.16 to 0.24) and negatively correlated with T10 (r = −0.18 to −0.36), T50 (r = −0.25 to −0.31) and U7525 (r = −0.11 to −0.24) under non-stress and salt stress conditions across 2 years’ seed batches, indicating faster germination and higher germination percentages of heavier seeds
Summary
In several species studies were done to identify quantitative trait loci (QTLs) for seed germination and seedling vigor traits under nonstress and abiotic stress conditions, e.g., in tomato (Foolad et al, 2007; Kazmi et al, 2012; Khan et al, 2012), rice (Wang et al, 2011, 2012), soy bean (Csanádi et al, 2001), wheat (Bai et al, 2013), barley (Mano and Takeda, 1997), Arabidopsis (Galpaz and Reymond, 2010; DeRose-Wilson and Gaut, 2011; Bouteillé et al, 2012), B. napus (Hatzig et al, 2015) and B. rapa (Dechaine et al, 2014) These studies have reported that seed germination and seedling vigor traits are regulated by many genes and are strongly affected by environmental conditions (Bettey et al, 2000; Koornneef et al, 2002; Finch-Savage et al, 2010)
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call