Touch-Induced Transcriptional Changes in Flower Buds of a Non-Model Horticultural Plant Dianthus hybrida

Abstract

Touch stimulus responses are common in plants. Some flowering plants sense the arrival of their pollinators and secrete nectar or release pollen sacs, facilitating successful pollination. Molecular mechanisms for mechanical stimulus responses in plants are well characterized in Arabidopsis leaves, but not in non-model plants or other organs such as flowers. Here, we performed RNA-seq analysis of touched flower buds of Dianthus hybrida, a major ornamental plant. Upon touch treatment, 931 and 132 genes were upregulated and downregulated, respectively. GO enrichment analysis revealed that genes encoding serine/threonine protein kinases were significantly abundant among the upregulated genes, which is consistent with previous studies that demonstrated the pivotal role of protein phosphorylation in the touch stimulus response of Arabidopsis leaves. In comparison with the gene expression profile of touched Arabidopsis leaves, the same families but different homologs of the representative touch-induced genes encoding protein kinases were upregulated, showing that phosphorelay signaling was the common mechanism for touch stimulus response in flowers and leaves, but the players of the phosphorelay signaling were different. These results will contribute to further studies on the mechanical stimulus responses of ornamental flowers and the utilization of this mechanism for breeding programs.