Plant Physiology∣中科院遺傳所謝旗研究組發文揭示ABA和生長素信號相互作用機制

2017年12月29日，Plant Physiology在線發表了中科院遺傳所謝旗研究組的文章。文章揭示了sHSP22通過調節生長素極性運輸進而調節對生長素的響應，而生長素誘導sHSP22的表達依賴於ABI1，進而提出了一個新的工作模型ABI1-sHSP22，它可以協調擬南芥中ABA和生長素信號相互作用。

原題目為：

The sHSP22 heat-shock protein requires the ABI1 protein phosphatase to modulate polar auxin transport and downstream responses

摘要：

植物激素ABA 和IAA 反應途徑協同或拮抗的相互作用，以調節植物發育和環境適應性。在這裡，ABA信號的關鍵負調節子ABI1，是生長素調節根發育所必需的。我們使用功能喪失的突變體abi1-3和用IAA 處理的Col-0 幼苗進行了微陣列分析。對於內質網小熱休克蛋白編碼基因sHSP22 受IAA的誘導，且依賴於ABI1。突變體shsp22 在主根系生長中表現出對ABA增強的敏感性。相反，過表達缺乏信號肽和ER保留序列的全長但不截短的sHSP22，導致ABA敏感性降低。過表達sHSP22 部分恢復了abi1-3 對的ABA超敏感性。此外，sHSP22在高溫處理中參與生長素調節的下胚軸伸長。由於潛在的增強了細胞內運輸，sHSP22也影響生長素外排載體PIN蛋白的積累。施用生長素後，sHSP22 過表達株系會產生更多的側根。我們的研究結果表明，sHSP22通過調節生長素極性運輸調節生長素的響應，而ABI1-sHSP22提供了一個新穎的模塊協調擬南芥中ABA和生長素信號相互作用。

Abstract：

The phytohormones abscisic acid (ABA) and indole-3-acetic acid (IAA) response pathways interact synergistically or antagonistically to regulate plant development and environmental adaptation. Here, we show that ABI1, a key negative regulator of ABA signaling, is essential for auxin-modulated root development. We performed a microarray analysis using the loss-of-function mutant abi1-3 and Col-0 seedlings treated with IAA. For sHSP22, an endoplasmic reticulum (ER) small heat shock protein-encoding gene, the induction by IAA was dependent on ABI1. shsp22 displayed enhanced sensitivity to ABA in primary root growth. In contrast, overexpression of full-length, but not truncated sHSP22 lacking signal peptide and ER-retention sequences, resulted in decreased ABA sensitivity. Overexpressed (OX) sHSP22 partially rescued the ABA hypersensitivity of abi1-3. In addition, sHSP22 is involved in auxin-regulated hypocotyl elongation at high temperature treatment. sHSP22 also affected accumulation of auxin efflux carrier PIN proteins due to potentiated intracellular trafficking. And sHSP22 OX lines initiated more lateral roots after auxin application. Our results suggest that sHSP22 regulates auxin response through modulating auxin polar transport, and ABI1-sHSP22 provides a novel module orchestrating ABA and auxin signaling crosstalk in Arabidopsis.