Genetic dissection of seed weight by QTL analysis and detection of allelic variation in Indian and east European gene pool lines of Brassica juncea

Abstract

Seed weight QTL identified in different populations were synthesized into consensus QTL which were shown to harbor candidate genes by in silico mapping. Allelic variation inferred would be useful in breeding B. juncea lines with high seed weight. Seed weight is an important yield influencing trait in oilseed Brassicas and is a multigenic trait. Among the oilseed Brassicas, Brassica juncea harbors the maximum phenotypic variation wherein thousand seed weight varies from around 2.0 g to more than 7.0 g. In this study, we have undertaken quantitative trait locus/quantitative trait loci (QTL) analysis of seed weight in B. juncea using four bi-parental doubled-haploid populations. These four populations were derived from six lines (three Indian and three east European lines) with parental phenotypic values for thousand seed weight ranging from 2.0 to 7.6 g in different environments. Multi-environment QTL analysis of the four populations identified a total of 65 QTL ranging from 10 to 25 in each population. Meta-analysis of these component QTL of the four populations identified six 'consensus' QTL (C-QTL) in A3, A7, A10 and B3 by merging 33 of the 65 component Tsw QTL from different bi-parental populations. Allelic diversity analysis of these six C-QTL showed that Indian lines, Pusajaikisan and Varuna, hold the most positive allele in all the six C-QTL. In silico mapping of candidate genes with the consensus QTL localized 11 genes known to influence seed weight in Arabidopsis thaliana and also showed conserved crucifer blocks harboring seed weight QTL between the A subgenomes of B. juncea and B. rapa. These findings pave the way for a better understanding of the genetics of seed weight in the oilseed crop B. juncea and reveal the scope available for improvement of seed weight through marker-assisted breeding.

QTL mapping and candidate gene mining for soybean seed weight per plant

“…Teng et al [13] constructed a molecular genetic map including 213 simple sequence repeat (SSR) markers distributed over 18 of 20 chromosomes (linkage groups) and identified nine QTLs associated with seed weight. QTLs controlling the seed weight have also been identified in other species, including rapeseed, chickpea and lentil [14][15][16][17].…”

A chromosome‐scale assembly of allotetraploid Brassica juncea (AABB) elucidates comparative architecture of the A and B genomes

“…The east European lines, as such, are ill‐adapted to the growing conditions in south Asia due to photoperiod sensitivity but contain a large number of positive traits like high pod density (Ramchiary et al ., 2007a,2007b; Yadava et al ., 2012), oil and seed meal quality (Gupta et al ., 2004; Rout et al ., 2015), and disease resistance (Arora et al ., 2019). Several QTL have been mapped in the Indian and east European gene pool lines (Dhaka et al ., 2017; Rout et al ., 2018). The Chinese vegetable types like Tumida constitute another divergent gene pool (Yang et al ., 2016) that contains potentially useful traits like serrated leaves, basal branching (Muntha et al ., 2018) and disease resistance (Bhayana et al ., 2019).…”

A chromosome-scale assembly of allotetraploid Brassica juncea (AABB) elucidates comparative architecture of the A and B genomes

“…The east-European lines, as such, are ill-adapted to the growing conditions in South Asia due to photoperiod sensitivity but contain a large number of positive traits like high pod density [38][39][40] , oil and seed meal quality [41][42] , and disease resistance 43 . Several QTL have been mapped in the Indian and East European gene pool lines [38][39][40][41][42][43][44] . The Chinese vegetable types like Tumida constitute another divergent gene pool 5 that contains potentially useful traits like serrated leaves, basal branching 45 , and stem strength.…”