The receptor-like protein kinases (RLKs) are the largest class of Arabidopsis protein kinases. This class, which based on phylogenetic analysis contains both transmembrane and cytoplasmic protein kinases, consists of at least 610 members and thus represents about 2.5% of the protein encoding genes in Arabidopsis . 417 of the RLK genes contain a putative ligand binding domain, a single transmembrane domain and a predicted cytoplasmic protein kinase domain, and thus are predicted to function as receptors. These 417 genes can be classified into 21 different types based on the sequences found in their extracellular domains. However, there is currently functional information on fewer than a dozen of the transmembrane RLKs. This research will focus on 61 of the 216 RLK genes that contain extracellular leucine-rich repeats (LRRs). Six well characterized RLK mutants in Arabidopsis thaliana :erecta, clavata1, brassinosteroid insensitive1, excess microsporocytes1, vascular highway1, and haesa belong to the LRR VII, X, XI and XII families. Based on what is known about the functions of these six well characterized LRR RLKs it is reasonable to hypothesize that many of the uncharacterized LRR VII, X, XI and XIII genes are likely to play interesting and important roles in plant growth and development. Two emerging themes are: that receptor kinases are part of a cellular network of regulatory proteins that includes physical interactions with other RLKs, and that some receptor kinases are involved in similar or overlapping processes. Using existing tools and technologies, the biological functions of each gene will be determined by isolation and characterization of both loss-of-function and gain-of-function mutations and examination of expression of the LRR VII, X, XI and XIII genes. The regulatory networks that mediate signaling by these protein kinases will also be defined.
Network of genes: The figure on the URL :www.mcb.arizona.edu/tax/login.cfm, shows a phylogenetic tree of the LRR RLKs in this project and a short description of the project. This will be linked to Frans Tax 's website. There will be links to this from TAIR, PlantsP and the websites from the other participants in the project.
Definition of determining the function: The function of these RLKs will be determined through the analysis of the phenotypes of single and multiple mutants and by analysis of the networks these RLKs participate in through results from the yeast two-hybrid system. Additional information to test for phenotypes will come from analysis of the expression patterns and from the analysis by others on RLK activity under specific environmental conditions.
What,how,when and where results will be shared: When single or multiple insertion or TILLING mutants are verified, they will be added to the project website and seeds sent to the stock center. The results of phenotypic screens using Gantlet protocols will be displayed on the website,as well photographs of the promoter:GUS expression patterns. These results will also be linked to PlantsP. All seed, strains and molecular reagents generated by this project will be deposited in the ABRC with a full description. Results from these experiments will also be presented at meetings and submitted for publication in a timely manner.
This 2010 project targets a unique set of plant genes of unknown function that are expected to have fundamental roles in the control of plant growth and development. Although a great deal is known about signaling networks in other organisms with completed genomes, relatively little is known about the mechanisms by which plant cells perceive and transduce developmental and environmental signals. The availability of several recently developed tools and technologies provides the means to rapidly advance the understanding of the biological functions of the LRR RLKs .
Broader Impacts The broader impacts of the project include the partnership with high school teachers to adapt the research materials for high school students participating in the Partnership for Research and Education in Plants (PREP), as well as the development of training workshops for teachers and scientists to prepare them to participate in PREP. This project also provides specific mentoring and training for undergraduate students that are members of underrepresented minority groups.
