Inositol polyphosphate 5-phosphatases （5PTases） are enzymes of phosphatidylinositol metabolism that affect various aspects of plant growth and development. Arabidopsis 5PTasel3 regulates auxin homeostasis and hormon...Inositol polyphosphate 5-phosphatases （5PTases） are enzymes of phosphatidylinositol metabolism that affect various aspects of plant growth and development. Arabidopsis 5PTasel3 regulates auxin homeostasis and hormonerelated cotyledon vein development, and here we demonstrate that its knockout mutant 5pt13 has elevated sensitivity to gravistimulation in root gravitropic responses. The altered responses of 5pt13 mutants to 1-N-naphthylphthalamic acid （an auxin transport inhibitor） indicate that 5PTase13 might be involved in the regulation of auxin transport. Indeed, the auxin efflux carrier PIN2 is expressed more broadly under 5PTasel3 deficiency, and observations of the internalization of the membrane-selective dye FM4-64 reveal altered vesicle trafficking in 5pt13 mutants. Compared with wild-type, 5pt13 mutant seedlings are less sensitive to the inhibition by brefeldin A of vesicle cycling, seedling growth, and the intracellular cycling of the PIN1 and PIN2 proteins. Further, auxin redistribution upon gravitropic stimulation is stimulated under 5PTasel3 deficiency. These results suggest that 5PTasel3 may modulate auxin transport by regulating vesicle trafficking and thereby play a role in root gravitropism.展开更多
文摘Inositol polyphosphate 5-phosphatases （5PTases） are enzymes of phosphatidylinositol metabolism that affect various aspects of plant growth and development. Arabidopsis 5PTasel3 regulates auxin homeostasis and hormonerelated cotyledon vein development, and here we demonstrate that its knockout mutant 5pt13 has elevated sensitivity to gravistimulation in root gravitropic responses. The altered responses of 5pt13 mutants to 1-N-naphthylphthalamic acid （an auxin transport inhibitor） indicate that 5PTase13 might be involved in the regulation of auxin transport. Indeed, the auxin efflux carrier PIN2 is expressed more broadly under 5PTasel3 deficiency, and observations of the internalization of the membrane-selective dye FM4-64 reveal altered vesicle trafficking in 5pt13 mutants. Compared with wild-type, 5pt13 mutant seedlings are less sensitive to the inhibition by brefeldin A of vesicle cycling, seedling growth, and the intracellular cycling of the PIN1 and PIN2 proteins. Further, auxin redistribution upon gravitropic stimulation is stimulated under 5PTasel3 deficiency. These results suggest that 5PTasel3 may modulate auxin transport by regulating vesicle trafficking and thereby play a role in root gravitropism.
