Validação de genes candidatos de arroz de terras altas (Oryza sativa L.) para tolerância à seca

• Autor(a) principal: Santos, Fabianna Ferreira dos
• Data de Publicação: 2017
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da UFG
• Texto Completo: http://repositorio.bc.ufg.br/tede/handle/tede/7987
• topic: Oryza sativa L; Expressão gênica; Produtividade de grãos; Resistência à seca; Estresse biótico; Oryza sativa L; Gene expression; Grain yield; Resistance to drought; Biotic stress; CIENCIAS BIOLOGICAS::BIOQUIMICA

Upland rice is grown without irrigation and the availability of water is totally dependent on the occurrence of rainfall. The objective of this study was to evaluate the differential expression of genes previously identified as responsive in drought conditions in upland rice genotypes grown under controlled irrigation and water restriction conditions. Two water treatments were applied, irrigation during the whole experiment and the water restriction, where irrigation was suspended for five days from the beginning of the reproductive stage (R2 / R3), with subsequent replacement of 50% of evapotranspirated water by irrigated plants at the base of the column for 10 days, followed by adequate irrigation until the end of the plant cycle. At the end of the crop cycle, evaluations of the production components (number of full grains, number of empty grains and mass of 100 grains) and yield were performed. Productivity estimates of 24 genotypes ranged from 44 to 170 g column-1 in the irrigated treatment and from 4 to 86 g column-1 in the water deficiency condition. The genotypes Três Meses Branco, BRS Esmeralda, BRSGO Serra Dourada, Casca Branca, BRSMG Curinga, Bico Ganga and Rabo de Burro were among the most productive genotypes both in irrigated condition and in water deficiency condition. Of the 24 genotypes used in the experiment described above, 12 contrasting yields in water treatments were characterized for differential expression for two target genes. One gene integrates the antioxidative defense system (Superoxide dismutase cofactor Manganese - MnSOD) and the other is a glycosyltransferase that promotes the glycosylation of an anthocyanin molecule (anthocyanidin 3-O-beta-D-glucosyltransferase). ANOVA based on the gene expression data revealed genotypes, water treatments and collection time in the gene expression (p≤0.05). The MnSOD gene presented the highest level of expression in all genotypes in the condition of greatest water restriction (five days without irrigation), with higher levels of expression in the less productive genotypes under stress conditions. On the other hand, the glycosyltransferase gene presented a considerably reduced expression in the most critical condition of the stress, without clear indicative of differentiation among the most productive genotypes during stress. The two genes evaluated were clearly responsive (p≤0.05) to the most severe water stress, but did not explain the differences between the genotypes grouped in the productivity estimates with and without dry stress. Therefore, it is possible to conclude that, due to the complexity in the processes adaptive to drought, each genotype uses different mechanisms of molecular responses, and it is not possible to differentiate them only through the genes evaluated in this study.