Identification of a major QTL for silique length and seed weight in oilseed rape (Brassica napus L.)

Abstract

Silique length (SL) and seed weight (SW) are two important yield-related traits controlled by quantitative trait loci (QTL) in oilseed rape (Brassica napus L.). The genetic bases underlying these two traits are largely unknown at present. In this study, we conducted QTL analyses for SL and SW using 186 recombinant inbred lines (RILs) derived from a cross between S1, an EMS mutant with extremely long siliques and large seeds, and S2, an inbred line with regular silique length and seed size. RILs were grown in Wuhan in the 2008/09 (SS09) and 2009/10 (SS10) growing seasons, and mean SL and SW for each line were investigated. Ten non-redundant QTL were identified for SL. Of these, a major QTL, cqSLA9, consistently explained as much as 53.4% of SL variation across environments. The others are minor QTL and individually explained less than 10% of the SL variation. Nine non-redundant QTL were identified for SW. Of which, one major QTL, cqSWA9, explained as much as 28.2% of the total SW variation in the SS09 and SS10 environments. In addition, three additive by additive interactions with small effects were detected for SL, and no interactions were detected for SW. Interestingly, the two major QTL, cqSLA9 for SL and cqSWA9 for SW colocalized in the same chromosomal region and were integrated into a unique QTL, uqA9. The S1 allele at this locus increases both SL and SW, suggesting that uqA9 has pleiotropic effects on both SL and SW. The existence and effect of uqA9 was confirmed in genetically different RILs derived from the cross between S1 and No2127, a resynthesized DH line having regular silique length and seed size. Individuals in one residual heterozygous line for cqSLA9 showed significant difference in silique length. The results in this study revealed that silique length in the S1 mutant is mainly controlled by the cqSLA9 locus, which will be suitable for fine mapping and marker-assisted selection in rapeseed breeding for high yield.

Development of a Statistical Crop Model to Explain the Relationship between Seed Yield and Phenotypic Diversity within the Brassica napus Genepool

“…From the correlation matrix, it became evident that traits previously used as a proxy for seed yield per plant, such as the number of seeds per pod [58], seed weight per pod [59], pod length [60] and even TGW, were not significantly correlated with seed yield per plant in this study (Figure 4). This finding indicates that current commercially-used measures, such as TGW, may not be the most appropriate indicator of yield for breeding and selection purposes.…”

Natural variation in ARF18 gene simultaneously affects seed weight and silique length in polyploid rapeseed

“…This QTL was localized to chromosome A09 and explained ∼30% of the phenotypic variation observed in SW. Interestingly, other rapeseed lines also harbored this QTL, as detected by Yang et al (26) and Li et al (27). In the present study, we used map-based cloning and targeted-region association to clone and characterize the gene related to the major QTL for SW. We further elucidated the possible mechanism…”

“…Rapeseed is an important global agricultural crop that has recently gained attention in the field of plant genomics. Despite the identification of more than 80 QTLs for SW across the 19 chromosomes of the B. napus genome (24)(25)(26)(27), no genes associated with these QTLs have been identified.…”

Extra-Large Seed Germplasms of Brassica Napus Created through Microspore Culture

“…TSW is a complex quantitative traits controlled by the main genes, plus multiple minor genes, and easily affected by environment [15,16]. The probability of obtaining big seed lines through conventional hybridization breeding is only 1/1,000 to 1/30,000, thus, it is difficult to obtain heritable large seed materials.…”