遮光对刺梨果实As A含量及其合成基因表达的影响

Effects of Shading on AsA Content and Expression of Genes Involved in AsA Synthesis in Rosa roxburghii Fruits

本研究以高维生素C (AsA)果树——刺梨(Rosa roxburghii Tratt.)为材料,采用生长发育过程中果实套袋的方法研究了遮光及梯度恢复光照对刺梨果实AsA积累及其合成基因表达的影响。结果表明,完全遮光处理果实内AsA的含量较自然光照显著降低,恢复光照后AsA积累量有所上升,但未恢复至自然光照水平。进一步的实时荧光定量PCR (qRT-PCR)分析表明,遮光会显著下调所检测的半乳糖途径中全部5个基因和糖醛酸途径中GalUR基因的转录水平,却对肌醇途径中的MIOX基因的表达具有上调作用;梯度恢复光照时,随着恢复时间的延长合成基因的转录水平总体上呈逐步上调趋势,且除MIOX基因以外的所有基因的表达均高于未恢复光照处理。以上结果表明,光照对于参与AsA合成的半乳糖途径及糖醛酸途径具有正调控作用,而遮光却促进了肌醇途径中MIOX基因的表达。

Rosa roxburghii Tratt., with high content L-ascorbic acid （AsA） in its fruits, were used as materials to investigate the effects of shading and light recovering in gradient on expression of the genes involved in AsA synthesis and accumulation using the methods of bagging fruit during growth period. The results showed that the content of AsA in fruit treated with complete shading was significantly lower than that in natural light., and the amount of AsA accumulation increased after the restoration of light, but did not turn to the natural light level. Further real-time fluorescence quantitative PCR （qRT-PCR） analysis showed that shading significantly reduced the transcriptional level of five genes in the galactosaccharide pathway and the GalUR gene in the glucuronic pathway, but increased the expression of the MIOX gene in the inositol pathway. However, the expression of MIOX gene in the inositol pathway was up-regulated. When the light was restored in gradient, with the prolongation of recovery time, the transcriptional level of genes was gradually up-regulated, and all of the gene expression levels were higher than those without restoring light, except MIOX gene. These findings suggested that light had positive regulation on galactose pathway and uronic acid pathway involved in AsA synthesis, while shading promoted the expression ofMIOX gene in inositol pathway.