Sucrose Protects Arabidopsis Roots from Chromium Toxicity Influencing the Auxin-Plethora Signaling Pathway and Improving Meristematic Cell Activity

Plants adapt to challenging growth conditions, such as the scarcity of nutrients or exposure to toxic metals, via changes in root system architecture. Chromium (Cr) is a non-essential element that when supplied in sublethal concentrations inhibits primary root growth through decreasing meristematic activity and affects photosynthesis. Here, we show that sucrose reverses the inhibitory effects of Cr(VI) on plant growth and development. Sucrose supplementation reactivated primary root growth under repressing Cr(VI) concentrations by restoring cell division and auxin distribution at the root meristem, keeping stem cell niche functioning. Analysis of the growth of Arabidopsis wild-type and mutant seedlings defective in auxin transport or signaling further revealed a critical role of auxin in mediating the effects of sucrose to protect plants from Cr(VI) toxicity. The results suggest that sucrose acts as a regulator in the maintenance of root meristem activity to overcome the stress generated by sublethal Cr(VI) concentrations.