Plant & Animal Genomes XIV Conference

January 14-18, 2006
Town & Country Convention Center
San Diego, CA

Functional Annotation And Analysis Of The GmCLAVATA1A Gene In Soybean

Tarik El Mellouki¹ , Faiza Tebbji¹ , Peter Gresshoff² , Khalid Meksem¹

¹  Plants and Microbes Genomics and Genetics lab; Department of Plant Soil and Agricultural Systems, Room 176. Southern Illinois University at Carbondale, Carbondale, IL 62901-4415. Fax: 618 453 7457; E-mail: meksemk@siu.edu;

²  Australian Research Council Centre of Excellence for Integrative Legume Research, The University of Queensland, St. Lucia, QLD. 4072, Australia;

In soybean, the investigation of gene mutations causing fasciation phenotype has led to the molecular identification of two homologous genes to A. thaliana CLAVATA1 (AtCLV1) in Glycine max (Yamamoto et al., 2000). The two homologous genes of AtCLV1 have been designated GmCLV1A and GmCLV1B (Yamamoto et al., 2000). In a recent investigation of long-distance nodulation signaling in Soybean, GmCLV1B has been identified as a regulator of root nodulation (Searle et al., 2003). Thus, it has been renamed GmNARK (for Glycine max Nodule Autoregulation Receptor Kinase). GmCLV1A and GmNARK have 92% similarities in their coding sequence (Yamamoto et al., 2000). The Arabidopsis thaliana AtCLV1 has 60% similarities to GmCLV1A and 62% to GmNARK (Yamamoto et al., 2000). GmNARK has been shown to be involved in the regulation of symbiosis nodules formation, however, the function of the GmCLV1A is still not determined.
We used TILLING (for Targeting Induced Local Lesions IN Genomes), to identify mutations in GmCLV1A as a step in the functional characterization of this gene in soybean. Several mutants were identified using three different pools of soybean M2 plants. The mutations identified in the pools were confirmed by screening individual plants. Samples carrying mutations were sequenced for lesions confirmation. The identified mutations ranked from silent to knock-out; they include missense and nonsense alterations. Despite the presence of non-linked background mutations, some mutants show a common phenotype. The main features of these mutants are a reduced internodal distance, leaves malformation and a high rate of stem and root lateral branching, which led us to hypothesize that GmCLV1A is involved in regulating soybean stem and root branching in addition to its implication in meristem maintenance.