title: Identification of legume RopGEF gene families and characterization of a Medicago truncatula RopGEF mediating polar growth of root hairs.
abstract: Root hairs play important roles in the interaction of plants with their environment. Root hairs anchor the plant in the soil, facilitate nutrient uptake from the rhizosphere, and participate in symbiotic plant-microbe interactions. These specialized cells grow in a polar fashion which gives rise to their elongated shape, a process mediated in part by a family of small GTPases known as Rops. RopGEFs (GEF, guanine nucleotide exchange factor) activate Rops to effect tip growth in Arabidopsis pollen and root hairs, but the genes mediating tip growth in legumes have not yet been characterized. In this report we describe the Rop and RopGEF gene families from the model legume Medicago truncatula and from the crop legume soybean. We find that one member of the M. truncatula gene family, MtRopGEF2, is required for root hair development because silencing this gene by RNA interference affects the cytosolic Ca2+ gradient and subcellular structure of root hairs, and reduces root hair growth. Consistent with its role in polar growth, we find that a GFP::MtRopGEF2 fusion protein localizes in the apex of emerging and actively growing root hairs. The amino terminus of MtRopGEF2 regulates its ability to interact with MtRops in yeast, and regulates its biological activity in vivo.
authors.affiliation: Department of Plant Pathology, University of California, One Shields Avenue, Davis, CA 95616, USA.
authors.forename: Brendan K
authors.initials: BK
authors.lastname: Riely
authors.forename: Hengbin
authors.initials: H
authors.lastname: He
authors.forename: Muthusubramanian
authors.initials: M
authors.lastname: Venkateshwaran
authors.forename: Birinchi
authors.initials: B
authors.lastname: Sarma
authors.forename: Joshua
authors.initials: J
authors.lastname: Schraiber
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Ané
authors.forename: Douglas R
authors.initials: DR
authors.lastname: Cook
mesh_terms: D000595:Amino Acid Sequence; D002118:Calcium / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D020662:Guanine Nucleotide Exchange Factors / Q000235:genetics / Q000378:metabolism*; D046913:Medicago truncatula / Q000235:genetics* / Q000254:growth & development* / Q000378:metabolism; D008969:Molecular Sequence Data; D020559:Monomeric GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018517:Plant Roots / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D030821:Plants, Genetically Modified; D011485:Protein Binding; D034622:RNA Interference; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D013025:Glycine max / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D015003:Yeasts / Q000378:metabolism
chemical_list: D020662:Guanine Nucleotide Exchange Factors; D010940:Plant Proteins; D011993:Recombinant Fusion Proteins; D020559:Monomeric GTP-Binding Proteins; D002118:Calcium