Figure 3. Genome-wide association study of low-temperature resistance in a panel of B. napus accessions.
(A) Manhattan plots and Q-Q plots for genome-wide association study of low temperature resistance phenotype measured in Year 2017 (top) and Year 2018 (bottom), respectively. (B) qRT-PCR analysis of the abundance of three candidate miRNAs after cold treatment for 0, 10, 20 and 30 days, respectively. Error bar represents mean ± SE;n = 3. U6 was used as the endogenous reference gene. * indicates P < 0.05; ** indicates P < 0.01; Student’s t-test. (C ) Haplotypes of candidate SNPs withinMIR1885 promoter for low-temperature resistance in B. napus population. LTR represents low-temperature element (CCGAAA). Five variants, including four SNPs and the one-bp deletion, which were significantly associated with low-temperature resistance, were marked with dark bold vertical lines. The five variants located in the 200-bp genomic region around LTR were used for analysis. ‘Hap.’ denotes the haplotypes of MIR1885 ; ‘Number’ denotes the number of lines belonging to each haplotype group. ‘Degree’ denotes the average grade of low-temperature resistance.