Differential accumulation of transcripts for ACC synthase homologs in etiolated mung bean hypocotyls in response to Li+

Abstract

In mung bean(Vigna radiate), 1-aminocyclopropane-1-carboxylate synthase (ACS) is encoded by a mutigene family that comprises at least seven members. Their expression is induced by hormones, developmental signals, inhibition of protein synthesis, or stress. We performed an RT-PCR assay to understand the differential accumulation of transcripts for ACC synthase homologs as a response to Li+ in etiolated mung bean hypocotyls. Treating the seedlings with liCI caused inductions of theACS1, ACS4, ACSS, ACS6, andACS7 genes. The induction level ofACS7 was particularly high. This effect onACS7 expression was specific, lasting more than 8 h after the treatment To understand the relationship of this Li+ action with the phosphoinositide (PI) second messenger system, we examined the effect of Ca2+ treatment on Li+-induction of theACS7 gene. Because Ca2+ did not reverse the Li+ effect, we suggest that regulation of theACS7 gene by Li+ in the mung bean may not involve the PI system.