Abstract
Although it's recognized that sugar-regulation of plant genes is mediated by multiple signal transduction pathways, molecular mechanisms underlining such regulation are largely unknown. We performed extensive screening of mutants of Arabidopsis thaliana in which expression of a LUC reporter gene under the control of sugar-inducible minimal promoter showed altered response to sugar. These mutants were classified into two groups; 25 lines which showed high LUC activity even under low-sucrose condition (hsi-type), and 24 lines which showed low LUC activity even under high-sucrose condition (lsi-type).
Three of the hsi-type mutants were further characterized with responsiveness of the LUC reporter expression, sensitivity of seed germination to sugar and ABA, endogenous level of ABA and expression of endogenous sugar-responsible genes. It's suggested that sugar-induced expression of LUC reporter gene is under the regulation of both ABA-dependent and -independent pathways. hsi2 mutation was mapped within about 40 kb region on chromosome 2.
