Arabidopsis phosphatidylinositol monophosphate 5-kinase 2 is involved in root gravitropism through regulation of polar auxin transport by affecting the cycling of PIN proteins  

作　　者：Yu Mei Wen-Jing Jia Yu-Jia Chu Hong-Wei Xue 

机构地区：[1]National Key Laboratory of Plant Molecular Genetics,Institute of Plant Physiology&Ecology,Shanghai Institutes for Biological Sciences,Chinese Academy of Sciences,300 Fenglin Road,Shanghai 200032,China

出　　处：《Cell Research》2012年第3期581-597,共17页细胞研究（英文版）

摘　　要：Phosphatidylinositoi monophosphate 5-kinase （PIP5K） catalyzes the synthesis of PI-4,5-bispbosphate （Ptdlns（4,5） P2） by phosphorylation of PI-4-phosphate at the 5 position of the inositol ring, and is involved in regulating multiple developmental processes and stress responses. We here report on the functional characterization of Arabidopsis PIP5K2, which is expressed during lateral root initiation and elongation, and whose expression is enhanced by exogenous auxin. The knockout mutant pip5k2 shows reduced lateral root formation, which could be recovered with exogenous auxin, and interestingly, delayed root gravity response that could not be recovered with exogenous auxin. Crossing with the DR5-GUS marker line and measurement of free IAA content confirmed the reduced auxin accu- mulation in pip5k2. In addition, analysis using the membrane-selective dye FM4-64 revealed the decelerated vesicle trafficking caused by PtdIns（4,5）P2 reduction, which hence results in suppressed cycling of PIN proteins （PIN2 and 3）, and delayed redistribution of PIN2 and auxin under gravistimulation in pip5k2 roots. On the contrary, PtdIns（4,5） P2 significantly enhanced the vesicle trafficking and cycling of PIN proteins. These results demonstrate that PIP5K2 is involved in regulating lateral root formation and root gravity response, and reveal a critical role of PIP5K2/Pt- dIns（4,5）P2 in root development through regulation of PIN proteins, providing direct evidence of crosstalk between the phosphatidylinositol signaling pathway and auxin response, and new insights into the control of polar auxin transport.

关 键 词：ARABIDOPSIS phosphatidylinositol monophosphate 5-kinase 2 （PIP5K2） root development polar auxin transport vesicle trafficking 

分 类 号：S567.190.4[农业科学—中草药栽培] TN929.53[农业科学—作物学]