Expressão gênica em sementes, espigas e plântulas de linhagens de milho associada à tolerância ao déficit hídrico

Abstract

The knowledge of genes related to water deficit in seeds and seedlings can be an important tool to aid and accelerate the process of selection maize genotypes more adapted to water deficit. Thus, the aim of this study was to evaluate the expression of genes related to the tolerance to water deficit in maize lines. Were used maize lines previously selected for tolerance to water deficit, two tolerant lines (L91-T and L32-T) and two not tolerant lines (L57-NT and L24-NT). The initial seed quality was evaluated by germination and accelerated aging test. For emergence and emergency speed index (ESI), the seeds of the four lines were seeded in substrate with sand, adjusted to 70% and 10% of the water retention capacity, consisting of no stress and stress condition, respectively; than, it was evaluated the root and shoot length of the seedlings. For proteomic analyzes, dry seeds, ears tips and seedlings were used with three, five and seven days after seeding submitted to two contrasting conditions of water availability of two maize lines (L91-T and L57-NT). The expression of catalase, peroxidase, esterase and heat-resistant proteins were evaluated by the electrophoresis technique. In the transcript analysis were studied the expression of the genes associated to stress tolerance ZmPP2C, ZmDREB2A/2.1S, ZmDBP3, ZmAN13, ZmALDH9, ZmLEA3 and AOX2 by the qRT-PCR technique. Can be conclude that, higher expression were obtained for ears tip in L91-T lines for catalase, peroxidase and esterase. There was a reduction in the enzyme expression of the catalase and esterase in seedlings after seven days of planting, for both lines analysed. Higher activity of the resistant heat proteins activity occured in dry seeds of line L91-T. Were identified potential genes as markers for the selection of maize lines tolerant to water déficit.