Matrix metalloproteinases (MMPs) are zinc-dependent endo-peptidases that in mammals are known to be involved in remodeling the extracellular matrix (ECM) in developmental and pathological processes. In this study, we report At5-MMP of Arabidopsis thaliana to be important for root development and root bacterial communities. At5-MMP is mainly localized in the root vasculature and lateral root, an At5-MMP T-DNA insertion mutant (mmp5 KO) showed reduced root growth and a lower number of root apexes, causing reduced water uptake from the soil. Subsequently, mmp5 KO is sensitive to drought stress. Inhibited auxin transport was accompanied with resistance to indole-3-acetic acid (IAA), 2, 4-dichlorophenoxyacetic acid (2, 4-D), and 1-naphthaleneacetic acid (NAA). The content of endogenous abscisic acid (ABA) was lower in roots of mmp5 KO than in wild type. Genes responsive to ABA as well as genes encoding enzymes of the proline biosynthesis were expressed to a lower extent in mmp5 KO than in wild type. Moreover, drought stress modulated root-associated bacterial communities of mmp5 KO: the number of Actinobacteria increased. Therefore, At5-MMP modulates auxin/ABA signaling rendering the plant sensitive to drought stress and recruiting differential root bacterial communities.

中文翻译：

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干旱胁迫下拟南芥基质金属蛋白酶5的缺失影响根系发育和根系细菌群落

基质金属蛋白酶 (MMP) 是锌依赖性内肽酶，已知在哺乳动物中，其在发育和病理过程中参与细胞外基质 (ECM) 的重塑。在这项研究中，我们报告了拟南芥的At5-MMP对根发育和根细菌群落很重要。At5-MMP 主要位于根脉管系统和侧根中，At5-MMP T-DNA 插入突变体 ( mmp5 KO ) 显示根生长减少和根尖数量减少，导致土壤吸水量减少。随后，mmp5 KO对干旱胁迫敏感。受抑制的生长素转运伴随着对吲哚-3-乙酸 (IAA)、2, 4-二氯苯氧乙酸 (2, 4-D) 和 1-萘乙酸 (NAA) 的抗性。mmp5 KO根系内源脱落酸（ABA）含量低于野生型。与野生型相比，对 ABA 有反应的基因以及编码脯氨酸生物合成酶的基因在mmp5 KO中的表达程度较低。此外，干旱胁迫调节了mmp5 KO 的根相关细菌群落：放线菌的数量增加。因此，At5-MMP调节植物生长素/ ABA信号传导，使植物对干旱胁迫敏感并募集不同的根细菌群落。