Isolamento e caracterização de genes da família SnRK e sua expressão em resposta ao déficit hídrico em Coffea canephora

• Autor(a) principal: Paiva, Rita Márcia Cardoso de
• Data de Publicação: 2009
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/4344
• topic: Estresse hídrico; Coffea canephora; SnRK; Water stress; Coffea canephora; SnRK; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::FITOTECNIA::FISIOLOGIA DE PLANTAS CULTIVADAS

Drought tolerance can result from numerous anatomical, morphological and physiological characteristics that can be from constituent or inductive nature. As one of the most important phytohormones known, abscisic acid (ABA) have been studied extensively and several of these studies it has been demonstrating that ABA is responsible for several responses adaptatives in the water deficit. This way, the isolation, caracterization and expression studies of genes that participate in signalling pathway in response to ABA, can supply important data for understanding its role and importance in the mechanism of drought tolerance in coffee. The aims of this work was identifies, in the bank of the coffee, genes belonging to the SnRK family besides verifying the responses in leaves and roots of clones of Coffea canephora, in conditions of severe and moderate water deficit. Plants of the clones 120 (drought tolerant genotype) and 109A (drought sensitive genotype) were cultivated in vases of 12 L and the water deficit was reached by suspending the irrigation until the plants reached -1,5 MPa and -3,0 MPa predawn hydric potential. Homology analyses, allowed the identification of 24 contigs that can represent possible genes of SnRK family in coffee, being 3 contigs of the subfamily SnRK1, 5 contigs in the subfamily SnRK2 and 16 sequences in the subgroup SnRK3. Among the identified sequences, 2 contigs, 15120 and 12770, in this investigation, we found that the ESTs of 15120 and 12770 correspond to different regions of the same gene, homologous to Arabidopsis SnRK2.6 and named cnSnRK2.6. A complete sequence of this gene that was put efficiently in vector of transformation of plants. The promoter sequence of this gene was also identified. Expression analyses, by Real Time quantitative PCR, showed that the expression patterns of some genes of this family are altered in ix conditions of water deficit, in leaves and roots of coffee. In leaves, the genes SnRK2.4, CIPK6 and CIPK9 were induced, while the genes SnRK2.3, CIPK3, CIPK8, CIPK10 and CIPK11 were repressed by the water deficit. However, in roots, the genes SnRK2.3, SnRK2.8, CIPK6, CIPK8 and CIPK9 were induced, what demonstrates that some genes presented a different behavior in those two organs. Furthermore, SnRK genes are also involved in the response to other abiotic stresses. In this study, we also verified the expression of these genes in response to the ABA, osmotic stress and saline stress. For that, a new experimental approach was tested, with use of outstanding leaves of coffee, that a fast and efficient form to studies in coffee. The obtained results indicated a reduction in estomatical aperture (gs) that was accompanied of reductions in liquid carbon assimilation (A) for the treatments with ABA and mannitol, while in the controls treatment any alteration was observed. Gene expression analyses demonstrated that many SnRKs genes are responsive to ABA, osmotic stress and saline stress. SnRK2.6 was induced by ABA and mannitol, but not by salinity. Collectively, these results indicate that the SnRKs characterized genes consist of kinases proteins involved in response to different abiotic stresses.