Enhanced drought resistance of Nicotiana tabacum by compartmentalized maize Malic enzyme expression

OITAVEN, PABLO; MULLER, GABRIELA LETICIA; LARA, MARÍA VALERIA; DRINCOVICH, MARÍA FABIANA

Paraná

Congreso; LIV Reunión Anual de SAIB; 2018

Sociedad Argentina de Investigación Bioquímica y Biología Molecular

Water availability decrease has negative effects in agriculture production. When soil water content drops beyond certain level, plants reduce thestomata aperture, with a concomitant dismiss in growth and yield. A maize NADP-malic enzyme (NADP-ME) was expressed in guard cells andvascular tissues of Nicotiana tabacum, driven by the Arabidopsis thaliana Potassium channel 1 promoter. The biochemical modifications inthose cells and tissues, produced by maize NADP-ME, are traduced in important phenotypic modifications in the whole plant. Compared toWild-Type plants (WT), the transgenic tobacco lines have higher levels of sucrose, glucose, and fructose in phloem exudates and veins, producesignificantly more biomass per water used and flower earlier than WT. Besides, CO2 fixation rates at CO2 levels above 400 ppm and lightintensity above 200 μmol m-2 s-1 are significantly higher in transgenic tobacco lines. Here, we aimed to study stomatal aperture, stomatalconductance and stress resistance during a shortage of water. Transgenic lines show significantly smaller stomata pores than WT in normalirrigation 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. Thesefindings show that the NADP-ME cell-specific expression causes important variations in transpiration rates and water use efficiency, emergingas an effective strategy to enhance drought resistance in the C3 plant Nicotiana tabacum.