Social Networks of Receptor-like Kinases Regulate Cell Identity in Arabidopsis thaliana

Abstract

Receptor-like kinases (RLKs) make up one of the largest gene families in Arabidopsis thaliana. These genes are required for various biological processes, including response to biotic stress, cell elongation, cell proliferation, and cell fate patterning. An emerging theme in Arabidopsis and other plants is that networks of RLKs are required to regulate a specific process throughout development involving spatial and temporal regulation of transcription factors. However, there are still many RLKs (>50%) with no known function.Several RLKs regulate epidermal development by contributing to early embryonic epidermal maintenance or to epidermal differentiation. In my first analysis, I characterize the role of two related RLKs GASSHO1 (GSO1) and GSO2 in epidermal differentiation. gso1 gso2 double mutants initially form an epidermis during embryogenesis, but analysis of post-embryonic root development indicates the mis-expression of epidermal-specific genes. Three previously characterized RLKs that are involved in epidermal development are also involved in meristem maintenance. In order to decipher the RLK gene networks controlling epidermal development and meristem maintenance, it is necessary to identify additional RLKs involved in both of these processes. I further identified roles for GSO1 and GSO2 in maintaining root growth and root apical meristem (RAM) activity. A future goal will be to elucidate the networks of RLKs, including GSO1 and GSO2 in regulating epidermal and RAM development.The development of the vasculature in plants is controlled by a vascular meristem, the procambium. Oriented cell divisions from the procambium produce phloem, to the periphery, and xylem, to the center of the plant. In a reverse genetic screen to determine to roles of the remaining RLKs with unknown function, we identified the RLK XYLEM INTERMIXED WITH PHLOEM1 (XIP1) that is required for vascular development. We show XIP1 is required for regulating the differentiation of the phloem and for the organization of xylem vessel elements. Our analysis indicates that XIP1 is part of a vascular meristem network, further emphasizing the importance of social networks of RLKs regulating a specific process in development.