A wheat phytohormone atlas spanning major tissues across the entire life cycle provides novel insights into cytokinin and jasmonic acid interplay.

Abstract

Although numerous studies have focused on phytohormones in specific organs or tissues at different development stages or under various abiotic and biotic stress conditions, our understanding of the distribution and relative abundance of phytohormones throughout the entire life cycle of plants remains insufficient. Here, we present a phytohormone atlas resource obtained from the quantitative analysis of eight major classes of phytohormones, comprising a total of 40 hormone-related compounds, throughout the complete life cycle of wheat. In combination with transcriptome analysis, we established a wheat phytohormone metabolic regulatory network (WPMRN). Using the WPMRN dataset and Gene Ontology enrichment analysis, we swiftly characterized the function of TaLOG5-B1 in cytokinin biosynthesis. Furthermore, a detailed investigation of the WPMRN dataset uncovered transcription factor-mediated co-regulatory mechanisms among different classes of phytohormones. We focused specifically on the metabolic regulation of cytokinin and jasmonic acid, and functionally characterized the genes TaLOG3-D1 and TaAOS-D1 that are involved in the biosynthesis of these phytohormones, respectively, along with their regulatory transcription factor genes TaDOF3A and TaDOF5.6B. The functions of these genes were validated in transgenic plants, revealing their ability to co-regulate radicle length. These findings serve as a case study that highlights the utility of this resource for studying phytohormone metabolic regulatory networks in cereal crops and for gaining insights into the roles of phytohormones in enhancing agronomic traits.