Effect of Gibberellin on the Biosynthesis of Tocopherols in Oilseed Rape (Brassica napus L.) and Arabidopsis

摘要

Elevating the yield and altering the composition of seed tocopherols (Toc's) are important to rapeseed breeding and production. However, little is known about the biosynthesis of Toc's in response to environmental signals. In this study, we investigated the effects of exogenous gibberellin (GA(3)) and paclobutrazol (PAC) on Toc biosynthesis. We also explored the interactive effects between the two plant growth regulators (PGRs) and other factors, such as PGR treatment duration, genotype, and growing location on the total Toc yield and composition in oilseed rape seed. GA(3) significantly enhanced the production of Toc's and elevated the alpha-/gamma-Toc ratio in a time- and genotype-dependent manner. By contrast, PAC significantly reduced Toc yield. Genotypic differences were observed in the effects of GA(3) on Toc yield and composition in the seeds. GA(3) significantly increased the Toc yield and alpha-/gamma-Toc ratio in Zheyou-50, a genotype with a low proportion of very long chain fatty acids (VLCFAs). However, GA(3) did not significantly influence these parameters in Jiu-Er-13Xi, a genotype with a high VLCFA proportion. The increased Toc yield induced by GA(3) was mediated by the upregulation of genes (BnPDS1 and BnVTE1) that catalyze the production of Toc precursors. Therefore, applying GA(3) can improve rapeseed quality by increasing Toc yield and improving Toc composition.