Mechanisms of Rapid Alkalinization Factor Induced Growth Arrest in Arabidopsis

描述（由申请人提供）：是什么决定了多细胞生物的形状和大小是生物学中的一个基本问题。植物提供了一个相对简单的系统来研究这个问题，因为它们的组织和细胞类型比动物少。本研究的目的是了解肽激素快速碱化因子（RALF）拮抗植物生长，特别是细胞伸长的分子机制。将外源RALF肽应用于生长中的幼苗会导致根和芽的生长停滞，而RALF的系统过表达会导致半矮秆植物的生长。所有被检测的植物基因组都包含至少一个RALF肽编码基因，这表明RALF在植物生长中起着重要作用。ralf诱导生长阻滞的分子细节目前尚不清楚，了解这种肽激素如何影响生长可以使植物生物学家操纵植物结构以改善作物。本提案中概述的实验结合了生理学，基因组学和遗传学方法来了解模式植物拟南芥中的RALF功能。具体来说，实验旨在了解RALF信号如何拮抗生长素和油菜素类固醇诱导的幼苗生长，并通过对RALF1肽处理的幼苗进行微阵列实验来建立转录生长网络。基因筛选的目的是发现ralf诱导的生长停滞所需的基因。迄今为止所描述的植物肽激素受体是富含亮氨酸的重复受体样激酶（LRR-RLK），我们预计RALF肽受体也将是LRR-RLK。动物系统中的LRR-RLKs在器官发育和免疫中发挥重要作用；因此，了解这些类型的受体如何发挥作用将具有广泛的意义。总之，这些实验将开始揭示RALF的作用机制，并显著增加植物细胞如何生长的当前模型。

DESCRIPTION (provided by applicant): What determines the shape and size of multicellular organisms is a fundamental question in biology. Plants offer a relatively simple system to study this question because they have fewer tissues and cell types than animals. The objective of this study is to understand the molecular mechanisms by which the peptide hormone Rapid Alkalinization Factor (RALF) antagonizes plant growth, specifically cell elongation. Application of exogenous RALF peptide to growing seedlings causes growth arrest of both roots and shoots, and systemic over-expression of RALF results in semi-dwarf plants. All plant genomes examined contain at least one RALF peptide-encoding gene, pointing to a fundamental role in plant growth. The molecular details of RALF-induced growth arrest are currently unknown, and understanding how this peptide hormone influences growth could allow plant biologists to manipulate plant architecture for the improvement of crops. The experiments outlined in this proposal combine physiological, genomic, and genetic approaches to understand RALF function in the model plant Arabidopsis thaliana. Specifically, the experiments are designed to understand how RALF signaling antagonizes auxin and brassinosteroid-induced growth in seedlings and to develop a transcriptional growth network by performing microarray experiments with seedlings treated with RALF1 peptide. Genetic screens have been designed to discover genes required for RALF-induced growth arrest. Receptors for plant peptide hormones described to date have been leucine rich repeat receptor-like kinases (LRR-RLKs), and we anticipate that a RALF peptide receptor would also be an LRR-RLK. LRR-RLKs in animal systems play important roles in organ development and immunity; therefore, understanding how these types of receptors function will have wide reaching implications. Together, these experiments will begin to unravel the mechanisms RALF action and add significantly to the current model of how plant cells grow.