Abstract
BackgroundBrassica napus is one of the most important oilseed crops, and also an important biofuel plant due to its low air pollution and renewability. Growth period are important traits that affect yield and are crucial for its adaptation to different environments in B. napus.ResultsTo elucidate the genetic basis of growth period traits, genome-wide association analysis (GWAS) and linkage mapping were employed to detect the quantitative trait loci (QTL) for days to initial flowering (DIF), days to final flowering (DFF), flowering period (FP), maturity time (MT), and whole growth period (GP). A total of 146 SNPs were identified by association mapping, and 83 QTLs were identified by linkage mapping using the RIL population. Among these QTLs, 19 were pleiotropic SNPs related to multiple traits, and six (q18DFF.A03-2, q18MT.A03-2, q17DFF.A05-1, q18FP.C04, q17DIF.C05 and q17GP.C09) were consistently detected using both mapping methods. Additionally, we performed RNA sequencing to analyze the differential expression of gene (DEG) transcripts between early- and late-flowering lines selected from the RIL population, and the DEGs were integrated with association mapping and linkage analysis to confirm their roles in the growth period. Consequently, 12 candidate genes associated with growth period traits were identified in B. napus. Among these genes, seven have polymorphic sites in the coding sequence and the upstream 2-kb sequence based on the resequencing data. The haplotype BnaSOC1.A05-Haplb and BnaLNK2.C06-Hapla showed more favorable phenotypic traits.ConclusionsThe candidate genes identified in this study will contribute to our genetic understanding of growth period traits and can be used as targets for target mutations or marker-assisted breeding for rapeseed adapted to different environments.
Highlights
Brassica napus (B. napus, genome AACC, 2n = 38) is one of the most important oilseed crops and an important source of protein-rich livestock feed in the world
Five quantitative trait loci (QTL) found in the genome-wide association analysis (GWAS) and 15 QTLs identified in the linkage mapping were co-associated with at least two growth period traits, which coincided with significant phenotypic correlations among the traits (Additional file 24: Table S14a, b)
146 Single nucleotide polymorphism (SNP) and 83 QTLs associated with the five growth period traits (DIF, days to final flowering (DFF), flowering period (FP), maturity time (MT) and GP) were identified by association and linkage mapping techniques
Summary
Due to the energy crisis, low air pollution and renewability of rapeseed oil, an increasing number of people regard rapeseed oil as an ideal green energy source. This species is an allopolyploid (AACC) that. Flowering is a major trait in the plant’s growth period, as it represents the transition from the vegetative stage to the reproductive stage. Brassica napus is one of the most important oilseed crops, and an important biofuel plant due to its low air pollution and renewability. Growth period are important traits that affect yield and are crucial for its adaptation to different environments in B. napus
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