Identificação de genes com expressão diferencial em folhas de cafeeiro Coffea canephora e Coffea arabica submetidas a differentes condições de estresse hidrico : [Preprint]

Aiming at the establishment of a breeding program based on marker-assisted selection for drought tolerance on coffee, the present work had as a goal, the identification of candidate genes for this trait by using an integrated approach (gene expression and proteomics). The data was obtained by comparing gene expression and protein profile of different genetic materials (Tolerant vs. Susceptible) as well as, under different conditions of water supply (Irrigated vs. Non-irrigated). In this work, the genetic materials studied were the conillon clones 22 and 14 (Coffea canephora) and the cultivars Rubi and Iapar 59 (Coffea arabica). The applied water stress (?PD=-3,0 MPa) to the conillon plants was achieved under green-house conditions and, in the case of Arabica, adult plants cultivated under field conditions were studied. In the later case, leaves were collected during day and night, and the most pronounced observed water-stress was of ?PD=-1,7 MPa. After selection of candidate genes by different strategies, the expression was confirmed by qPCR analysis. The data obtained indicated that several genes displayed decreased expression upon water stress and usually these were encoding-genes of proteins involved in photosynthesis. On the other hand, the applied water stress on coffee plants also induced a set of genes such as RD29, DREBA and NAC, which have already been described in literature as genes involved in plant responses to drought. In the case of a Dehydrin encoding-gene, the data obtained in this work confirmed previously observed differential expression on C. canephora, on C. arabica, also. However, this study revealed the importance of other factors controlling the expression of these genes, such as the circadian clock, the age as well as the profile of the plants and, these observations make the interpretation of differential expression data obtained from field trials even more complex. (Résumé d'auteur)