拟南芥ARS1和ARA1协同调控ABA诱导木栓质生物合成及功能研究

植物激素脱落酸(ABA)可以参与调节植物抵抗逆境的多种生理反应。已知ABA可诱导木栓质等生物大分子的合成，构成具有保护作用的细胞壁，形成屏障性结构。然而，有关ABA如何通过调节木栓质合成以控制水分运输的机制还不清楚。我们发现一个ABA响应的BAHD酰基转移酶ARS1，当该基因发生突变时，其根部木栓质单体的含量明显降低，并且种皮通透性加大。利用拟南芥酵母文库筛选得到一个与ARS1直接相互作用的ABCG转运蛋白ARA1，该基因受ABA诱导表达量明显上调。本项目拟以ars1和ara1突变体为遗传材料，结合生物化学、分子遗传学等多种生物学方法，探讨ARS1和ARA1参与ABA诱导木栓质合成的分子机理，解析ABA信号与根部内皮层栓质化重塑的关系，构建ABA诱导木栓质合成以调节水分运输的信号转导网络。该项目的实施，不仅丰富了ABA信号转导网络，也将为干旱等逆境胁迫下如何控制植物水分散失提供新途径。

Abscisic acid (ABA) is a universal hormone in higher plants and plays a major role in response to various aspects of stresses, including drought, salt stress, etc. Previous studies have shown that ABA can induce the biological synthesis of suberin. Suberin is deposited as a secondary cell wall, and it can also form a barrier structure, to prevent plants from excessive water loss. The formation of cell wall-based diffusion barriers serves a crucial function in establishing efficient transport pathways. However, the mechanism of ABA-regulated suberin synthesis and then control water transportation is not clear. We found a BAHD family acyltransferase gene, ARS1 (Abscisic acid-related suberin synthesis acyltransferase 1), which can be induced by ABA. To investigate the function of ARS1-related suberin synthesis, we first examined the seed coat permeability of the T-DNA insertion ars1 mutant line using tetrazolium Red, and found that ars1 showed enhanced red staining. These results indicate that ARS1 is essential for seed coat to maintain impermeability. We then tested the reduction of suberin monomer in root. HPLC analysis of the root cell wall revealed that the content of ferulate, ferulate derviates and p-coumarate, the primary phenolics in root, was reduced in ars1 root compared with those wild types. Screening to identify whether proteins can interact with ARS1 or not, we used a yeast of two-hybrid cDNA library from Arabidopsis thaliana, and found that ARS1 interacts strongly with ARA1 (ARS1-related ABCG), encoding an ABCG transporter. Interestingly, ARA1 might be dramatically up-regulated by ABA. In this project, we will use ars1 and ara1 mutants, in combination of the methods of plant physiology, biochemistry, and molecular genetics etc., to explore the molecular mechanism of how ARS1 and ARA1 is involved in ABA-induced suberin synthesis, and analyze the relationship between ABA and the reshaped root endodermis. In addition, we will also explore how to construct the signal transduction network of the ABA-induced suberin synthesis to regulate water transport. Through the implementation of the project, this research not only enriches the ABA signal transduction network, but also provides a new way of understanding how to control water loss under the drought stress.