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Arabidopsis PC aP2 modulates the phosphatidylinositol 4,5‐bisphosphate signal on the plasma membrane and attenuates root hair elongation
Author(s) -
Kato Mariko,
Tsuge Tomohiko,
Maeshima Masayoshi,
Aoyama Takashi
Publication year - 2019
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.14226
Subject(s) - root hair , microbiology and biotechnology , phosphatidylinositol 4,5 bisphosphate , phosphatidylinositol , arabidopsis , green fluorescent protein , mutant , chemistry , elongation , arabidopsis thaliana , biophysics , biochemistry , biology , signal transduction , gene , materials science , ultimate tensile strength , metallurgy
Summary Phosphatidylinositol 4,5‐bisphosphate [PtdIns(4,5)P 2 ] serves as a subcellular signal on the plasma membrane, mediating various cell‐polarized phenomena including polar cell growth. Here, we investigated the involvement of Arabidopsis thaliana PC aP2, a plant‐unique plasma membrane protein with phosphoinositide‐binding activity, in PtdIns(4,5)P 2 signaling for root hair tip growth. The long‐root‐hair phenotype of the pcap2 knockdown mutant was found to stem from its higher average root hair elongation rate compared with the wild type and to counteract the low average rate caused by a defect in the PtdIns(4,5)P 2 ‐producing enzyme gene PIP 5K3 . On the plasma membrane of elongating root hairs, the PC aP2 promoter‐driven PC aP2–green fluorescent protein ( GFP) , which complemented the pcap2 mutant phenotype, overlapped with the PtdIns(4,5)P 2 marker 2x CHERRY ‐2x PH PLC in the subapical region, but not at the apex, suggesting that PC aP2 attenuates root hair elongation via PtdIns(4,5)P 2 signaling on the subapical plasma membrane. Consistent with this, a GFP fusion with the PC aP2 phosphoinositide‐binding domain PC aP2 N23 , root hair‐specific overexpression of which caused a low average root hair elongation rate, localized more intense to the subapical plasma membrane than to the apical plasma membrane similar to PC aP2– GFP . Inducibly overexpressed PC aP2– GFP , but not its derivative lacking the PC aP2 N23 domain, replaced 2x CHERRY ‐2x PH PLC on the plasma membrane in root meristematic epidermal cells, and suppressed FM 4‐64 internalization in elongating root hairs. Moreover, inducibly overexpressed PC aP2 arrested an endocytic process of PIN 2– GFP recycling. Based on these results, we conclude that PC aP2 functions as a negative modulator of PtdIns(4,5)P 2 signaling on the subapical plasma membrane probably through competitive binding to PtdIns(4,5)P 2 and attenuates root hair elongation.