Transcriptome and proteome analyses of the molecular mechanisms underlying changes in oil storage under drought stress in Brassica napus L.

Abstract

Abstract Rapeseed (Brassica napus L.) is the second most important oilseed crop in edible vegetable oil and bioenergy; however, drought stress generally causes a decrease in rapeseed yield and oil content, especially during the reproductive stage. In our study, we measured the oil and protein contents and gibberellic acid (GA) and abscisic acid (ABA) levels in seeds that were acquired on the 30th, 40th, and 50th days after flowering under control and drought treatments. RNA and protein libraries were constructed from the stressed seeds to perform transcriptome and proteome analyses, respectively. Our results demonstrated that the oil content decreased due to four primary mechanisms: downregulation of fatty acid biosynthesis‐associated genes and proteins; upregulation of fatty acid degradation‐associated genes and proteins; enhancement of protein storage due to changes in the abundances of relevant genes and proteins; and upregulation of Gly‐Asp‐Ser‐Leu (GDSL) gene expression, potentially as the result of upregulating the GA biosynthesis gene GA20ox3 and downregulating the GA inactivating gene GA2ox3 and thus an increase in GA content. During seed maturation, oil storage change may also relate to increasing ABA content as the upregulation of two members of NCED6 (9‐cis‐epoxycarotenoid dioxygenase) gene family involved in ABA biosynthesis, and the upregulation of genes involved in ABA signal transduction. These results will help to establish a foundation for breeding excellent varieties of rapeseed with high oil content for areas with frequent droughts to promote the supply of edible vegetable oil and biofuel.

Keywords

• Brassica napus L
• Drought stress
• proteome
• seed oil content
• transcriptome