Mutual antagonism between auxin and diacylglycerol acyltransferase 2 regulates high‐temperature‐induced hypocotyl elongation

Abstract

Cell elongation is a fundamental process in plant growth and development, and it is significantly affected by temperature changes. While the signaling mechanisms driving high‐temperature‐induced cell elongation have been extensively studied, the strategies plants employ to counteract excessive temperature‐induced elongation remain poorly understood. Using Arabidopsis thaliana hypocotyls as a model, we show that high temperature induces the triacylglycerol biosynthetic enzyme DGAT2, which acts as a growth‐restraining regulator that counterbalances auxin‐driven elongation. Auxin, in turn, downregulates DGAT2 expression, establishing a feedback loop that limits excessive hypocotyl elongation under high temperature. Thermo‐ and auxin‐responsive regulation of DGAT2, and its role in modulating membrane lipid order, are conserved between Arabidopsis and Camelina, indicating a shared DGAT2–auxin regulatory module. Our study reveals how lipid metabolism, auxin homeostasis, and membrane dynamics intersect to shape hypocotyl adaptive responses, thereby optimizing growth under high‐temperature conditions.