ENHANCED DROUGHT RESISTANCE OF Nicotiana tabacum BY COMPARTMENTALIZED MAIZE MALIC ENZYME EXPRESSION

LARA, MARÍA V.; OITAVEN, PABLO; DRINCOVICH, MA. FABIANA; MÜLLER, GABRIELA L.

PARANA

Congreso; LIV Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2018

Water availability decrease has negative effects in agriculture production. When soil water content drops beyond certain level, plants reduce the stomata aperture, with a concomitant dismiss in growth and yield. A maize NADP-malic enzyme (NADP-ME) was expressed in guard cells and vascular tissues of Nicotiana tabacum, driven by the Arabidopsis thaliana Potassium channel 1 promoter. The biochemical modifications in those cells and tissues, produced by maize NADP-ME, are traduced in important phenotypic modifications in the whole plant. Compared to Wild-Type plants (WT), the transgenic tobacco lines have higher levels of sucrose, glucose, and fructose in phloem exudates and veins, produce significantly more biomass per water used and flower earlier than WT. Besides, CO2 fixation rates at CO2 levels above 400 ppm and light intensity above 200 μmol m-2 s-1 are significantly higher in transgenic tobacco lines. Here, we aimed to study stomatal aperture, stomatal conductance and stress resistance during a shortage of water. Transgenic lines show significantly smaller stomata pores than WT in normal irrigation conditions and are not modified during water stress. Stomatal conductance study shows significant differences within WT andtransgenic lines before the stress and after the rehydration. Drought injury was significantly higher in WT than in transgenic lines. These findings show that the NADP-ME cell-specific expression causes important variations in transpiration rates and water use efficiency, emerging as an effective strategy to enhance drought resistance in the C3 plant Nicotiana tabacum.