科研之友
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摘要
Ascorbic acid (AsA) is one of the most important antioxidants as well as being a growth regulator and enzymatic cofactor in plants. The biosynthesis of AsA in plants is well characterized while the regulation of its accumulation remains largely unexplored. In the present work, the AsA concentration throughout tomato fruit development and ripening was lower in High-Pigment-1 (hp1) with differential accumulation pattern as compared to wild-type (WT) plants. The transcriptional abundance of genes involved in AsA synthesis was also investigated during tomato fruit development. The result showed that transcriptional profiles of 14 genes involved in AsA biosynthesis were differentially regulated in hp1 fruits. The expression of genes encoding GDP-mannose pyrophosphorylase (GMP), GDP-mannose-3',5'-epimerase (GME1 and GME2) and l-galactose-1-phosphate phosphatase in hp1 was generally higher than that in WT, while the expression of gene encoding monodehydroascorbate reductase was lower than in WT. The expression abundance of GMP (P < 0.01) and GME1 (P < 0.05) were negatively correlated with AsA accumulation in WT tomato fruits. In the hp1 fruits, however, the expression level of gene encoding the last step enzyme, l-galactono-1,4-lactone dehydrogenase (GLDH), was negatively correlated with AsA accumulation (P < 0.05). Thus the reduced AsA accumulation in hp1 tomato fruits is associated with negative transcriptional regulation of GLDH, which offsets the increased expression of GMP and GME1. The probable mechanism of AsA down-regulation in hp1 fruit is discussed.
- 出版日期2014-2
- 单位华中农业大学
