Transcriptome profiles of phytohormone-related genes in Populus tomentosa vegetative buds from endodormancy to ecodormancy

Bud dormancy activity is a crucial developmental event for growth and survival in woody perennials, and phytohormones play vital roles in this process. In the present study, endodormant and ecodormant vegetative buds were collected from Populus tomentosa and the transcriptomes from two periods were then analyzed and compared using RNA sequencing, aiming at exploring the associations between plant hormones and bud endodormancy release. Among 91,447 assembled unigenes, 7117 were differentially expressed during the transition from endodormancy to ecodormancy. Enrichment analyses revealed that many differentially expressed genes (DEGs) were assigned to hormone-related pathways, indicating the involvement of hormones during endodormancy release. Subsequently, various genes involved in hormone metabolism, transport, and signal transduction were identified and discussed. These hormones include abscisic acid, gibberellin, ethylene, auxin, and cytokinin. In addition to the five traditional hormones, we examined the differential expression patterns of genes in the brassinosteroid- and jasmonate-related pathways. All expression changes in the identified genes further demonstrated that phytohormones participate in endodormancy release. This is the first systematic investigation of the expression patterns of hormone-associated genes in endodormancy release in P. tomentosa at molecular level. This work provides important insights into the associations between hormones and dormancy in perennial trees, and will be beneficial for further studies on the complex mechanisms of bud dormancy. © 2020 SAAB