Eficiência do uso da água em plantas transgênicas de Nicotiana tabacum L. com atividade sacarolítica alterada especificamente em células guardas

Abstract

Stomata are small structures in the leaf epidermal, composed of two guard cells (CG) that surround and regulate the opening and closing of the stomatal pore. Stomatal movements regulate the atmospheric CO2 influx for photosynthesis and the efflux of water via transpiration, being thus important for regulation the water use efficiency (EUA) in plants. Recent results suggest that sucrose degradation is an important process during stomatal opening. Thus, the genetic manipulation of sucrose metabolism in CG is a potential tool to optimize the EUA in plants. In this context, the present work aimed to evaluate the EUA in tobacco plants wild type (WT) and transgenic strains (L3, L11 and L13) with decreased expression of potato sucrose synthase 3 (StSUS3) under the control of the stomatal-specific KST1 promoter. The results showed that under irrigated conditions, transgenic plants showed reductions of up to 44% in the whole plant transpiration when compared to wild plants, in addition to significant reductions in stomatal conductance (gs) and increased EUA. Furthermore, a reduction in the accumulation of total biomass was observed in transgenic plants, although these plants showed greater allocation of resources to the aerial part, culminating in an increase in the harvest rate in one of the transgenic strains. Taken together, the results demonstrate that the change in the expression of the StSUS3 gene substantially modifies the transpiration pattern of the plant and can act as an effective option to increase the EUA in plants.