Avanços genéticos na resposta do arroz de terras altas aos estresses bióticos.

Abstract

The studies presented highlight advances in rice genetic breeding, focusing on resistance to biotic stresses. The first study addressed the severity of rice blast (Magnaporthe oryzae) in elite upland rice genotypes. Using 36 years of data from the National Blast Nursery (VNB), the impacts of environmental factors on disease expression and genetic progress in resistance were analyzed. An accumulated progress of -4.50 in disease severity was observed over the seasons, with temperature being the main factor associated with increased disease incidence. Strategies such as environmental stratification were essential to identify mega-environments and optimize the selection of lines adapted to regional conditions. The second study focused on the overexpression of the DREB1a gene in a transgenic rice line and its potential use in resistance to soil fungi. The transgenic plants demonstrated better development, especially in the root system, even under biotic stress conditions, compared to the wild-type parent. This result suggests that the DREB1a gene, in addition to being widely associated with tolerance to abiotic stresses, plays a significant role in responses against soil fungi. Both studies reinforce the importance of integrating biotechnology with conventional breeding to develop more adapted and resistant cultivars, promoting sustainability and productivity in rice cultivation.