向日葵种子发育过程中油脂合成相关miRNA的挖掘和表达分析

Excavation and expression analysis of miRNA related to oil synthesis during seed development in sunflower

为探究miRNA(microRNA)在向日葵种子油脂合成中的作用,解析植物油脂合成分子调控机制,基于前期高油酸向日葵种子三个发育时期(开花后7 d、22 d、37 d)miRNA测序的结果,对影响油脂合成代谢的miRNA进行挖掘和表达分析。结果发现L7d vs L22d、L7d vs L37d和L22d vs L37d三组比较中参与油脂代谢通路的差异表达miRNA共有22个。表达量聚类热图分析发现,22d vs 37d比较组中大部分miRNA下调表达,表明油脂代谢相关的大部分miRNA在开花后37 d相比于22 d表达量降低。将靶基因注释到脂肪酸和三酰甘油合成通路中的22个差异表达miRNA在种子发育不同时期的表达量与种子含油量和脂肪酸组分进行相关性分析,结果分别发现己酸与miR172a3,十三烷酸与miR171b2均呈极显著负相关,油分含量与miR167d5p呈显著正相关,表明这些miRNA可能参与油脂的合成。通过共表达分析发现,有6对油脂代谢相关的miRNA(miR166u、miR171b_2、miR397a_3、miR157d、miR167a-5p、miR169v_1)与其靶基因呈负相关的共表达关系,表明这些基因的差异表达可能是miRNA调控的结果。

In order to explore the role of miRNA(microRNA)in seed oil synthesis of sunflower,miRNA sequencing in 3 development stages(7 d,22 d,37 d after flowering)of high oleic acid sunflower seeds were mined.Results showed that 22 differentially expressed miRNAs were involved in oil metabolism pathway based on comparisons of L7d vs L22d,L7d vs L37d and L22d vs L37d.Clustering heat map showed that most miRNAs in the 22d vs 37d comparison group were down-regulated,indicating that the expression of most miRNAs related to oil metabolism decreased at 37 d after flowering compared with 22 d after flowering.The 22 differentially expressed miRNAs annotated with target gene into fatty acid and triacylglycerol synthesis pathway were analyzed for the correlation between expression level and fatty acid components at different stages of seed development.Results also showed that caproic acid and miR172a3,tridecylic acid and miR171b2 were both extremely significantly negatively correlated,and oil content was significantly positively correlated with miR167d5p,indicating that these miRNAs might be involved in oil synthesis.Through co-expression analysis,it was found that 6 miRNAs related to oil metabolism(miR166u,miR171b_2,miR397a_3,miR157d,miR167a-5p,miR169v_1)were negatively correlated with their target genes,indicating that the differential expression of these genes might be the result of miRNA regulation.