Role of a LRR-RLK in Regulating Ethylene Biosynthesis and Anisotropic Cell Elongation in Roots

细胞如何调控其增殖是现代生物学的中心问题。在植物中，细胞的不对称扩张是器官大小和形状的主要决定因素。然而，人们对植物细胞扩张调控的分子机制知之甚少。从拟南芥中鉴定出一对类似受体的激酶，称为AIK1和AIK2，它们直接与ACC合成酶相互作用，ACC合成酶是催化植物激素乙烯生物合成的限速步骤。遗传学研究表明，这些AIK基因在调节根细胞中的细胞扩张方面发挥着重要作用。乙烯促进植物细胞的径向膨胀，aik1/aik2双突变体的放射状膨大表型依赖于乙烯。这一点，再加上观察到这些蛋白质直接与ACC合成酶相互作用，表明这些AIK基因参与了乙烯和定向细胞扩张之间的相互作用。这种相互作用将通过精确描述AIK突变对根的生长特征的影响以及确定这些基因是否直接调节参与引导细胞伸长的细胞特征(如细胞壁)来进一步探索。将使用遗传和生化方法探索乙烯在AIK突变表型中的作用。最后，将在酵母中使用简单的交互屏幕来寻找这些AIK激酶的其他靶点。这项研究将阐明植物如何调节细胞伸长，这对了解植物形态的发育至关重要。该提案还将为本科生和研究生提供不同领域的跨学科培训机会，包括细胞生物学、植物生理学、分子遗传学和生物化学。

How cell regulate their expansion is central question in modern biology. In plants, asymmetric cell expansion is a primary determinant of the size and shape of organs. However, very little is known regarding the molecular mechanisms underlying the regulation of cell expansion in plants. A pair of receptor-like kinases from Arabidopsis, called AIK1 and AIK2, has been identified that directly interact with ACC synthase, the enzyme that catalyzes the rate-limiting step in the biosynthesis of the plant hormone ethylene. Genetic studies have revealed that these AIK genes play an important role in regulating cell expansion in root cells. Ethylene promotes radial expansion of plant cells, and the radial swelling phenotype in the aik1/aik2 double mutant was found to be dependent on ethylene. This, coupled with the observation that these proteins directly interact with ACC synthase, suggests that these AIK genes are involved in the interaction between ethylene and directed cell expansion. This interaction will be further explored by precisely delineating the effects of the AIK mutations on the growth characteristics of the root and by determining if these genes directly regulate features of the cell involved in directing cell elongation, such as the cell wall. The role of ethylene in the aik mutant phenotype will be explored using genetic and biochemical approaches. Finally, additional targets of these AIK kinases will be sought using a simple interaction screen in yeast. This research will shed light on how plants regulate cell elongation, which is crucial to understanding the development of plant form.The proposal will also provide interdisciplinary training opportunities for undergraduate and graduate students in diverse areas including cell biology, plant physiology, molecular genetics, and biochemistry.