Expressão de genes relacionados à tolerância ao estresse hídrico em sementes e em tecidos de plântulas de milho

Abstract

Water stress is one of the limiting factors for the development of corn, and the knowledge of genes related to this stress in dry seeds and seedlings can be an important tool to accelerate the selection process. Thus, the aim of this study was to evaluate the expression of genes related to tolerance to water stress in different tissues and seeds of corn in different genotypes. The initial quality of the seeds were evaluated by the accelerated aging test. For proteomic and transcriptomic analyzes, seeds from four tolerant genotypes (91 -T, 32-T, 91x75- T, 32x75-T,) and four non-tolerant (37-NT, 57-NT, 37x57-NT and 31x37-NT) previously selected for tolerance to drought stress were sown in substrate containing 70% and 10% of soil water retention capacity, characterized without and with stress respectively. Was evaluated the expression in dry seed, shoot and root seedlings under stress or not. The expression of catalase (CAT), horseradish peroxidase (PO), superoxide dismutase (SOD), esterase (EST), and heatresistant protein (CRP), were evaluated by electrophoresis, as well as the expression of genes associated with drought tolerance, ZmLEA3, ZmALDH9, ZmPP2C, ZmCPK11, ZmDREB2A/2.1s, ZmDREB2.7, ZmDBP3, ZmAN13 and cAPX by qRT-PCR. Expression of CAT, PO, SOD, EST and PRC differed between genotypes and in seeds, roots and shoots of corn seedlings. Increased expression of the enzymes SOD and CAT were observed in inbred lines, and even greater expression of CAT in shoots of seedlings of corn hybrids. The expression of the enzyme PO was higher in the shoot when compared to the root under stress condition. There was a higher expression of the enzyme in EST genotypes classified as intolerant to water stress. The PRC is expressed only in seeds. The expression of genes ZmLEA3, ZmALDH9, ZmPP2C, ZmCPK11, ZmDREB2A/2.1s, ZmDBP3, ZmAN13 and cAPX differed between genotypes and in seeds, roots and shoots of corn seedlings. Greater expression of genes ZmLEA3, ZmALDH9, ZmCPK11 were observed in the shoots of corn plants, classified as tolerant and even the genes ZmAN13, ZmPP2C and cAPX. There was a greater expression of the genes ZmAN13 ZmDREB2A/2.1S in roots under stress condition.