Root hair development is crucial for phosphate absorption, but how phosphorus deficiency affects root hair initiation and elongation remains unclear. We demonstrated the roles of auxin efflux carrier PIN-FORMED2 (PIN2) and phospholipase D (PLD)-derived phosphatidic acid (PA), a key signaling molecule, in promoting root hair development in Arabidopsis thaliana under a low phosphate (LP) condition. Root hair elongation under LP conditions was greatly suppressed in pin2 mutant or under treatment with a PLDζ2-specific inhibitor, revealing that PIN2 and polar auxin transport and PLDζ2-PA are crucial in LP responses. PIN2 was accumulated and degraded in the vacuole under a normal phosphate (NP) condition, whereas its vacuolar accumulation was suppressed under the LP or NP plus PA conditions. Vacuolar accumulation of PIN2 was increased in pldζ2 mutants under LP conditions. Increased or decreased PIN2 vacuolar accumulation is not observed in sorting nexin1 (snx1) mutant, indicating that vacuolar accumulation of PIN2 is mediated by SNX1 and the relevant trafficking process. PA binds to SNX1 and promotes its accumulation at the plasma membrane, especially under LP conditions, and hence promotes root hair development by suppressing the vacuolar degradation of PIN2. We uncovered a link between PLD-derived PA and SNX1-dependent vacuolar degradation of PIN2 in regulating root hair development under phosphorus deficiency.

中文翻译：

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磷脂酶D衍生的磷脂酸通过抑制PIN-FORMED2的液泡降解来促进缺磷情况下的根毛发育。

根毛的发育对于磷酸盐的吸收至关重要，但是磷缺乏如何影响根毛的萌生和伸长尚不清楚。我们展示了生长素外排载体PIN-FORMED2（PIN2）和磷脂酶D（PLD）衍生的磷脂酸（PA）（一种关键的信号分子）在低磷（LP）条件下促进拟南芥根毛发育中的作用。在pin2突变体中或在用PLDζ2特异性抑制剂处理的情况下，LP条件下的根毛伸长被大大抑制，这表明PIN2和极性植物生长素转运和PLDζ2-PA在LP反应中至关重要。PIN2在正常磷酸盐（NP）条件下在液泡中积累并降解，而在LP或NP加PA条件下其液泡积累受到抑制。在LP条件下，pldζ2突变体中PIN2的液泡积累增加。在分选nexin1（snx1）突变体中未观察到PIN2液泡积累的增加或减少，这表明PIN2的液泡积累是由SNX1和相关的运输过程介导的。PA与SNX1结合并促进其在质膜上的积累，特别是在LP条件下，因此通过抑制PIN2的液泡降解来促进根毛发育。我们发现了在缺磷的情况下，PLD衍生的PA和PIN2依赖于SNX1的液泡降解之间的联系可调节根毛的发育。PA与SNX1结合并促进其在质膜上的积累，特别是在LP条件下，因此通过抑制PIN2的液泡降解来促进根毛发育。我们发现了在缺磷的情况下，PLD衍生的PA和PIN2依赖于SNX1的液泡降解之间的联系可调节根毛的发育。PA与SNX1结合并促进其在质膜上的积累，特别是在LP条件下，因此通过抑制PIN2的液泡降解来促进根毛发育。我们发现了在缺磷的情况下，PLD衍生的PA和PIN2依赖于SNX1的液泡降解之间的联系可调节根毛的发育。