Single-cell-level response to drought in Sorghum bicolor reveals novel targets for improving water use efficiency

Increasing drought threatens global agriculture, especially in water-limited regions. Sorghum bicolor , a drought-tolerant C ₄ grass, is a promising bioenergy crop for cultivation on marginal lands, yet its molecular drought responses remain poorly understood. To uncover single-cell-level transcriptional responses to drought, we performed single-nucleus RNA sequencing on mature sorghum leaves under well-watered and drought conditions. We identified major cell types and analyzed differential gene expression across mesophyll, bundle sheath, epidermal, vascular, and stomatal cells. Surprisingly, drought effects on transcriptomes exceeded differences due to cell identity, revealing a shared response across cell types. We leveraged this convergence to identify candidate regulators of drought-responsive gene expression. These findings advance our understanding of sorghum drought adaptation and offer new targets for engineering enhanced water use efficiency in bioenergy crops.