title: Spatial expression of CLAVATA3 in the shoot apical meristem suggests it is not a stem cell marker in soybean.
abstract: CLAVATA3 (CLV3), a stem cell marker in Arabidopsis thaliana, encodes a secreted peptide that maintains the stem cell population within the shoot apical meristem. This work investigated the CLV3 orthologue in a major legume crop, soybean (GmCLV3). Instead of being expressed in the three outermost layers of the meristem as in Arabidopsis, GmCLV3 was expressed deeper in the central zone beneath the fourth layer (L4) of the meristem, overlapping with the expression of soybean WUSCHEL. Subsequent investigation using an alternative stem cell marker (GmLOG1) revealed its expression within layers L2-L4, indicating that GmCLV3 is not a stem cell marker. Overexpression studies of GmCLV3 in Arabidopsis and complementation of clv3-2 mutant suggest similar functional capacity to that of Arabidopsis CLV3. The expression of soybean CLV1, which encodes a receptor for CLV3 in Arabidopsis, was not detectable in the central zone of the meristem via reverse-transcription PCR analysis of amplified RNA from laser-microdissected samples or in situ, implicating a diverged pathway in soybean. This study also reports the novel expression of GmLOG1 in initials of axillary meristem in the boundary region between the SAM and developing leaf primordia, before the expression of GmWUS or GmCLV3, indicating cytokinin as one of the earliest signals in initiating and specifying the stem cell population.
authors.affiliation: Plant Molecular Biology and Biotechnology Laboratory, ARC Centre of Excellence for Integrative Legume Research, Melbourne School of Land and Environment, The University of Melbourne, Parkville, Victoria 3010, Australia.
authors.forename: Chui E
authors.initials: CE
authors.lastname: Wong
authors.forename: Mohan B
authors.initials: MB
authors.lastname: Singh
authors.forename: Prem L
authors.initials: PL
authors.lastname: Bhalla
mesh_terms: D000595:Amino Acid Sequence; D029681:Arabidopsis Proteins / Q000235:genetics*; D015415:Biomarkers / Q000032:analysis*; D018506:Gene Expression Regulation, Plant; D005816:Genetic Complementation Test; D018519:Meristem / Q000235:genetics*; D008969:Molecular Sequence Data; D009154:Mutation; D009928:Organ Specificity; D010940:Plant Proteins / Q000235:genetics*; D018520:Plant Shoots / Q000235:genetics / Q000378:metabolism*; D018547:Plant Stems / Q000235:genetics*; D030821:Plants, Genetically Modified; D017386:Sequence Homology, Amino Acid; D013025:Glycine max / Q000235:genetics*
chemical_list: C118167:AT2G27250 protein, Arabidopsis; D029681:Arabidopsis Proteins; D015415:Biomarkers; D010940:Plant Proteins
keywords: CLAVATA3; cytokinin; shoot apical meristem; soybean; stem cell.