Abstract
Microarray analyses suggest that mRNA levels of about 5% of Arabidopsis genes are up-regulated in response to sugar, and the sugar-induction of more than 80% of them is blocked by the inhibition of protein synthesis. We selected putative transcription factors whose expression is rapidly induced by sugar even in the presence of cycloheximide. AtSCL4 and AtSCL15 are GRAS proteins belonging to different subfamilies. Expression of both AtSCL4 and AtSCL15 was regulated by sugar metabolic signal at the level of transcription, and they exhibited different spatial expression patterns. Over-expression of AtSCL4 or AtSCL15 caused enhanced expression of many sugar-inducible genes that include AOS for the synthesis of jasmonic acid (JA) and many JA-responsible genes. JA didn't induce expression of AtSCL4 and AtSCL15 and spatial expression patterns of AtSCL15 and AOS were similar, suggesting that sugar-regulated expression of AtSCL4 andAtSCL15 modulates expression of JA-responsible genes by affecting the synthesis of JA.
