Transcriptome Analysis of Brassica napus Wax-Deficient Mutant Revealed the Dynamic Regulation of Leaf Wax Biosynthesis is Associated with Basic pentacysteine 6

摘要

Wax is a protective layer through which plants directly contact the environment and it plays an important role in plantresponses to biotic and abiotic stresses. The biosynthesis of wax is a dynamic process that occurs over different growth stages.Although wax biosynthesis has been well studied, there are limited reports on how plants regulate wax synthesis at differentdevelopmental stages. In this study, we identified a wax-deficient mutant (wad) in rapeseed (Brassica napus L.). The wad trueleaf was shiny at the young stage (wad-y) but recovered at the mature stage (wad-m) and further analyses indicated that waxbiosynthesis was blocked in wad-y leaves. The gene expression patterns of wild-type (WT) during the young (WT-y) andmature (WT-m) stages, wad-y and wad-m were monitored using RNA sequencing. The Kyoto Encyclopedia of Genes andGenomes (KEGG) annotation showed that differentially expressed genes (DEGs) were gathered in the fatty acid elongationpathway. These genes were down-regulated in wad-y and returned to normal levels in wad-m, indicating that the changes infatty acid elongation genes’ expression lead to dynamic changes in wax. Moreover, a transcription factor-enrichment analysisshowed that BASIC PENTACYSTEINE 6 (BPC6) is the key regulator affecting fatty acid elongation. Taken together, our studyshowed BPC6 potentially affects the biosynthesis of wax during different developmental stages by regulating the elongation offatty acid chains. This study will provide new insights into the regulation of wax biosynthesis during different developmentalstages of rapeseed.