Abstract
D-Mannose/L-Galactose pathway for ascorbate (AsA) biosynthesis has been established recently, while the mechanism of AsA metabolism regulation is still unknown. In this work AsA deficient Arabidopsis mutant vtc2-1 was incubated with AsA precursor L-galactone-1,4-lactone (L-GalL) and developed higher AsA content especially under light. Using whole genome DNA microarray, transcriptome abundance of incubated vtc2-1 was analyzed for screening AsA responsible genes. Several genes were sensitive to L-GalL incubation and were up-regulated significantly. After analyzing the genes expression level by real-time PCR, an aspartyl protease (ASP) and a ring zinc finger protein performed synchronous expression responsive to L-GalL supplementation and AsA pool size change, but not to the addition of D-glucose. Transgenic Arabidopsis plants containing the promoter reporter system were developed and verified that the expression of ASP gene accords with real-time PCR results. These identifications suggest novel clues for understanding the regulation mechanism of AsA pool size regulation in higher plants.
