期刊
PLANT CELL TISSUE AND ORGAN CULTURE
卷 96, 期 1, 页码 105-112出版社
SPRINGER
DOI: 10.1007/s11240-008-9466-x
关键词
L-Ascorbate; L-Galactonolactone; L-Galactonolactone dehydrogenase; Overexpression
资金
- Ministry of Agriculture, Forestry, and Fisheries, Japan
L-Galactono-1,4-lactone (GalL) dehydrogenase (GLDH) is an enzyme that catalyzes the last step of L-ascorbate (AsA) biosynthesis in plants. To re-evaluate the importance of the enzyme and the possibility of manipulating the AsA content in plants, a cDNA encoding GLDH from sweet potato was introduced into tobacco plants by Agrobacterium-mediated transformation under the control of a CaMV 35S promoter. Protein blot analysis revealed the elevation of GLDH protein contents in three GLDH-transformed lines. Furthermore, these transgenic lines showed 6- to 10-fold higher GLDH activities in the roots than the non-transformed plants, SR1. Despite the elevated GLDH activity, the AsA content in the leaves did not change in all lines; i.e., the AsA content in GLDH-transformed lines was 3-7 mu mol g(-1) FW, comparable to that in the non-transformed plants. Incubation of leaf discs in a GalL solution led to a rapid 2- to 3-fold increase in the AsA content in both GLDH-transformed and non-transformed plants in the same manner. These results suggest that the supply of GalL is a crucial factor for determining the AsA pool size and that the upstream genes in the AsA biosynthetic pathway are responsible for enhancing the AsA content in plants.
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