Single-cell transcriptomes reveal spatiotemporal heat stress response in pearl millet leaves.

With the intensification of global warming, there is an urgent need to develop crops with enhanced heat tolerance. Pearl millet, as a typical C4 heat-tolerant crop, has mechanisms of heat tolerance at the cellular level which remain unclear. Constructed single-cell transcriptomic landscape of pearl millet leaves under heat stress and normal conditions, comprising 20 589 high-quality cells classified into five cell types. Vascular tissue cells were identified as the most critical cell type under heat stress, characterized by the highest number of differentially expressed genes and heat stress memory genes. Through single-cell WGCNA analysis combined with phenotypic and physiological analysis of heat stress memory gene UGT73C3 mutants and overexpression lines, we revealed the important role of heat stress memory genes in enhancing heat tolerance by promoting the clearance of reactive oxygen species accumulation. Our study provides a heat-tolerant crop leaf atlas revealing insights into heat tolerance and laying a foundation for generating more robust crops under the changing climate.