Características agronômicas e expressão de proteínas relacionadas ao déficit hídrico em milho

Abstract

Drought is one of the factors that limits the most the development of plants and maize grain yield. Understanding the characteristics of water deficit is fundamental for the identification and selection of drought-tolerant genotypes. When selecting a genotype, many strategies can be used, including phenotypic and molecular markers. Therefore, the objective was to evaluate the influence of water deficit on agronomic characteristics and the expression of enzymes of the antioxidant system in leaves, roots and seeds ininbred lines and hybrids of maize.The experiment was carried out in a greenhouse at the Department of Agriculture of the Universidade Federal de Lavras(UFLA). Two inbred lines (L91 and L31) and two maize hybrids (31/91 and 91/31) were used, contrasting in terms of drought tolerance, classified in previous works. In the first experiment, the agronomic characters evaluated were: plant height, tassel size, the interval between female and male flowering and number of seeds per plant. Statistical differences were observed in all characteristics, except for number of seeds.It is concluded that agronomic characteristics related to the flowering of maize plants and tassel length may be associated with tolerance to water deficit and can be used as an indicator to select new drought-tolerant cultivars. The second experiment was carried out with the same inbred lines and hybrids and it was measure the expressions of the enzymes,catalase (CAT), esterase (EST), peroxidase (POX), superoxide dismutase (SOD) and total proteins, by the electrophoresis technique and the quantification of CAT, SOD, EST, ascorbate peroxidase (APX) and total proteins, by the technique of the microplate spectrophotometry, in leaves, roots and seeds of maize submitted to two water regimes (with and without water deficit). Variations in the expressions of catalase, esterase, peroxidase and superoxide dismutase were observed, evaluated by the electrophoresis technique, in the inbreds and hybrids and in the evaluated tissues, depending on the water management used.As for quantification, by the microplate spectrophotometry technique, there were variations in protein values, depending on the inbred and hybrid, tissue and water regime. For most of the evaluated genotypes, there is greater expression of proteins under water deficit condition. The highest activity of SOD, CAT, POX enzymes were observed in leaves and roots of plants submitted to water deficit and the highest activity of the esterase enzyme were observed in leaves, roots, and seeds, regardless of whether the roots growth occurred under water deficit or not. Therefore, protein markers and agronomic traits may be associated with drought tolerance in maize.