Unlocking Wheat's Heat Stress Survival Secrets: A Comprehensive Study of Spike Development’s Metabolic Responses

Wheat exhibits a heightened sensitivity to heat during spike differentiation, and varietal characteristics and the duration of exposure influence its ability to withstand such stress. Wheat can enhance its resistance to heat stress by regulating the synthesis of endogenous "stress hormones," but understanding the precise molecular mechanisms involved has remained a formidable challenge. This study focused on the Xinjiang spring wheat variety "Xinchun 9" during the period spanning from 2020 to 2021. We subjected the wheat to heat stress treatments at three critical stages of spike differentiation. We utilized RNA-seq and DIA techniques to analyze wheat spikes' transcriptome and proteome comprehensively. In summary, we conducted quantitative analyses on 105,200 transcripts and 19,503 proteins. Remarkably, we observed significant enrichment of differentially expressed genes (DEGs) and proteins (DEPs) associated with secondary metabolite synthesis, plant hormone signaling, and metabolic pathways. Hierarchical clustering analysis further unveiled the distinct stage-specificity of these DEGs/DEPs, emphasizing their rapid response to short-term heat stress. Of particular interest, essential genes/proteins involved in abscisic acid (ABA) synthesis and proline metabolism pathways exhibited significant upregulation or downregulation. It suggests the activation of ABA and proline-mediated heat tolerance pathways. Furthermore, the swift activation of arginase and ornithine aminotransferase (OAT) underscores the pivotal role of proline synthesis through the ornithine pathway. Our study offers a clearer panoramic perspective, illuminating wheat spikes' genetic and proteomic changes under heat stress conditions. It provides novel insights into the genetic regulation of heat stress at various stages of wheat spike differentiation.