Abstract
We isolated an Arabidopsis mutant sicy-192 whose cotyledon greening was inhibited by treatments with sugars, such as sucrose and glucose. In the mutant, the gene encoding plastidic alkaline/neutral invertase (INV-E) was point-mutated at codon 294, with Tyr substituted for Cys. The greening of cotyledons in the knockout-INV-E lines was not inhibited by treatment with the sugars. On treatment with sucrose, the expression of photosynthesis-related genes was weaker in mutant seedlings than wild-type seedlings. Moreover, in the mutant seedlings the activity of nitrate reductase and the levels of nitrate and glutamate were increased. These findings suggest that Cys294 of INV-E is associated with the development of the photosynthetic apparatus and the assimilation of nitrogen in Arabidopsis seedlings. Now, we are analyzing the activity and stability of INV-E:C294Y during greening in vivo.
