Abstract
Plant vacuoles are complicated and multi-functional organelle. The Arabidopsis shoot gravitropism 2 (sgr2) mutant isolated as a gravitropic mutant in the inflorecence stem and the hypocotyl, has defect both in amyloplasts movement and in vacuolar function in endodermal cells. Our previous study has suggested that amyloplasts movement important for gravity sensing is closely related to the dynamics of vacuoles. The SGR2 encodes a protein homologous to bovine phospholipase A1, which is localized mainly to vacuolar membrane and small organelles. To investigate the molecular function of SGR2, we performed a genetic screen for the second mutation suppressing the defect of sgr2-1 gravitropic phenotype. The kiritsu171 (krt171) mutation suppressed abnormal amyloplasts movement of sgr2-1. Based on the map position, we found a mutation in a gene encoding a putative acyltransferase containing an EF-hand motif and a transmembrane domain. Taken together, KRT171 and SGR2 may be involved in the modulation of vacuolar dynamics.
