Drought resistance and improved yield result from modified malate metabolism in guard and vascular companion cells

Abstract

Drought is a major threat to food security. Water loss through stomata is an inevitableconsequence of CO2 uptake, and water deficit inhibits plant growth, making it challengingto develop drought-resistant strategies without compromising yield. Here, we generatedtobacco plants expressing a maize NADP-dependent malate decarboxylating enzyme instomata and vascular cells (ME plants), which show higher seed yield and faster maturationcompared to wild-type (WT) plants under normal irrigation and after drought. While WTplants die after 45 days of drought, ME plants survive without any adverse effects on seedproduction. In addition, ME plants exhibit improved photosynthetic efficiency despitereduced stomatal conductance and changes in stem morphology, which are likely relatedto their ability to withstand drought. We propose that enhanced C4-like biochemistry incells surrounding the vascular system and increased sugar export likely compensated forthe reduced stomatal conductance in ME plants. The study demonstrates that cell-targetedmetabolic modifications can avoid pleiotropic effects and facilitate the stacking ofbeneficial traits to improve crop design.