Abstract
The Arabidopsis ACL5 gene, whose inactivation causes a severe defect in the elongation of stem internodes, encodes a polyamine biosynthetic enzyme, spermine synthase. Although polyamines are recognized as being necessary for cell growth and proliferation, how they control the plant development remains to be understood. To elucidate the mechanism, we have isolated and characterized suppressor of acl (sac) 51d-54d mutants. In this study, we show that these sac mutations have no effect on the stem growth defects in a series of phytohormone-related mutants including axr2, gai, and dim. This result suggests that the function of these SAC genes is independent of phytohormone signaling pathways. Because the acl5 mutant contains spermine produced by another spermine synthase SPMS, the effects of sac mutations on the acl5 spms double mutant that has no spermine were examined. The result will be presented.
