Danger-Associated Peptides Interact with PIN-Dependent Local Auxin Distribution to Inhibit Root Growth in Arabidopsis

First author: Yanping Jing; Affiliations: Nanjing University (南京大学): Nanjing, China

Corresponding author: Sheng Luan

Plant elicitor peptides (Peps) are damage/danger-associated molecular patterns (DAMPs) that are perceived by the receptor-like kinases, PEPR1 and PEPR2, to enhance innate immunity and induce root growth inhibition in Arabidopsis. We report here that Arabidopsis Pep1 inhibited root growth in a PEPR2-dependent manner, which was accompanied by swelling epidermal and cortex cells and root hair formation in the transition zone (TZ). Interestingly, these Pep1-induced changes were mimicked by exogenous application of auxin and were suppressed in auxin perception mutants tir1 or tir1 afb1 afb2. Further analysis showed that Pep1-induced auxin accumulation in the TZ region preceded cell expansion in roots. As local auxin distribution depends on PIN-type auxin transporters, we examined Pep1-PEPR-induced root growth inhibition in several pinmutants and found that pin2 was more sensitive but pin3 was less sensitive to Pep1. The pin2 pin3 double mutant was similarly sensitive to Pep1 treatment as wild-type plants. Furthermore, we found that Pep1 reduced the abundance of PIN2 in plasma membrane through activating endocytosis pathway while increasing PIN3 expression in TZ region, leading to changes in local auxin distribution and root growth inhibition. These results formulate a unique model for Pep-PEPR signaling to crosstalk with auxin accumulation pattern in controlling of cell expansion and differentiation in the roots during immune responses.

植物激发子肽（Plant elicitor peptide, Pep）是损伤/危险相关分子模式DAMP，在拟南芥中能够被类受体激酶PEPR1和PEPR2所感知，从而增强植物的天然免疫，诱导根的生长抑制。本文中，作者报道了拟南芥的Pep1通过PEPR2依赖型的方式抑制根的生长，同时伴随着凸出的表皮和皮质细胞以及过渡区的根毛形成。有趣的是，作者发现这些由Pep1诱导的改变能够通过外施生长素来模拟，并且在生长素感知突变体tir1或者tir1 afb1 afb2中不会出现这些表型。进一步的分析显示，根中过渡区由Pep1诱导的生长素积累要先于细胞的扩张。由于局部的生长素分布依赖于生长素转运蛋白PINs，作者在一些pin突变体中研究了Pep1-PEPR诱导的根生长抑制情况，结果发现pin2突变体对于Pep1更加敏感，pin3突变体则不太敏感。另外，pin2 pin3双突变体对于Pep1处理的敏感程度与野生型类似。此外，作者还发现Pep1能够通过激活内吞途径来降低质膜上PIN2的丰度，同时增加过渡区中PIN3的表达，最终导致局部生长素分布的改变和根的生长抑制。本文的研究结果展示了Pep-PEPR信号通路与生长素积累模式的交叉作用，共同控制植物在免疫响应过程中根中细胞的扩张和分化。

通讯：Sheng Luan（https://plantandmicrobiology.berkeley.edu/profile/luan）

研究简介：植物响应和适应环境的分子机制。

doi: https://doi.org/10.1105/tpc.18.00757

Journal: Plant Cell

First Published: May 23, 2019