RESUMO
Plant hormones influence the key parameters that contribute to crop yield, including biomass, branching and seed number. We tested manipulation of cytokinin signaling as an avenue for influencing these growth parameters. Here we report a full-length cDNA coding for a cytokinin binding protein, Petunia cytokinin binding protein (PETCBP) from Petunia hybrida cv. Mitchell. PETCBP encodes for a protein that exhibits high sequence similarity to S-adenosyl-L-homocysteine hydrolase (SAHH). Transgenic petunia plants expressing this gene in antisense orientation displayed profuse branching, delayed flowering and delayed shoot bud induction from leaf explants in vitro. Homologs were also isolated from Arabidopsis thaliana homology-dependent gene silencing 1 (HOG1) and Orzya sativa (OsCBP). Arabidopsis HOG1 showed high affinity cytokinin binding activity and modified plant architecture similar to PETCBP. Transgenic Arabidopsis plants overexpressing HOG1 showed early flowering with a significantly reduced plant biomass and number of leaves. In contrast, profuse branching, delayed flowering, increased leaf size and higher seed yield were the major phenotypes observed in the antisense suppression lines. These results suggest that genetic manipulation of this cytokinin binding protein or its orthologs could be used for improving crop biomass and seed yield.
Assuntos
Adenosil-Homocisteinase/metabolismo , Proteínas de Arabidopsis/metabolismo , Arabidopsis/genética , Proteínas de Transporte/metabolismo , Citocininas/metabolismo , Petunia/genética , Proteínas de Plantas/metabolismo , Adenosil-Homocisteinase/genética , Sequência de Aminoácidos , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Biomassa , Proteínas de Transporte/genética , Citocininas/genética , DNA Complementar/genética , Flores/genética , Flores/metabolismo , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Dados de Sequência Molecular , Petunia/metabolismo , Fenótipo , Proteínas de Plantas/genética , Brotos de Planta/genética , Brotos de Planta/metabolismo , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/metabolismo , Plasmídeos , RNA de Plantas/genética , Alinhamento de Sequência , Transformação GenéticaRESUMO
Virus-induced gene silencing (VIGS) is a technology that exploits an RNA-mediated antiviral defense mechanism and has been shown to be of great potential in plant reverse genetics. Circumvention of plant transformation, methodological simplicity, robustness, and speedy results makes VIGS an attractive alternative instrument in functional genomics, even in a high throughput fashion. The system is well established in Nicotiana benthamiana, and efforts are being made to improve VIGS in other species, including monocots. Here, we discuss the issues specific to the application of VIGS technology to determine gene function, which has revealed the roles of a variety of genes in disease resistance, abiotic stress, cellular signaling and secondary metabolite biosynthesis.