NCP2/RHD4/SAC7, SAC6 and SAC8 phosphoinositide phosphatases are required for PtdIns4P and PtdIns(4,5)P2 homeostasis and Arabidopsis development

Phosphoinositides play important roles in plant growth and development. Several SAC domain phosphoinositide phosphatases have been reported to be for Here, we show functional analysis of SUPPRESSOR OF ACTIN 6 (SAC6) SAC8 Arabidopsis, a subfamily containing SAC-domain two transmembrane motifs. We isolated an Arabidopsis mutant ncp2 that lacked cotyledons seedling embryo pid, background defective auxin signaling transport. NCP2 encodes RHD4/SAC7 phosphatase. SAC6, SAC7 exhibit overlapping specific expression patterns embryo. The sac6 sac7 embryos either fail develop into seeds, or three four cotyledons. development sac8 mutants is significantly delayed lethal, the seedlings are arrested at early stages. Auxin maxima decreased double triple sac mutants. contents PtdIns4P PtdIns(4,5)P2 dramatically increased. Protein trafficking plasma membrane (PM)-localized protein PIN1 PIN2 from trans-Golgi network/early endosome back PM These results indicate SAC6–SAC8 essential maintaining homeostasis PtdIns(4,5)P2, auxin-mediated Arabidopsis.