Gene Characterization and Expression Analysis Reveal the Importance of Auxin Signaling in Bud Dormancy Regulation in Tea Plant

Abstract

The tea plant is an economically important woody plant whose raw leaves are used for tea production. Winter bud dormancy is not only a useful biological strategy for tea plant survival but also a biological event that affects the economics of tea production. Based on our previous transcriptome analysis of axillary buds in different dormancy states, we reanalyzed a large number of differentially expressed auxin-related genes and determined the relative importance of the roles of auxin signaling in bud dormancy regulation in tea plant. Subsequently, we cloned the full-length cDNA sequence of several auxin-related genes in the AUX/LAX, PIN/PILS, AUX/IAA, GH3, and SAUR gene families, characterized these genes and performed a phylogenetic analysis, and conserved motif search using the sequences of their encoded proteins. Expression profile analyses, including tissue-specific expression and time-course expression during the active-dormant-active status transitions of overwinter buds, were carried out, combined with IAA content detection. Generally, the expression patterns of auxin-related genes were consistent with the IAA content changes in buds and their active-dormant status transition. In particular, we confirmed the crucial roles of the auxin transport gene CsLAX2 and the early auxin response genes CsGH3.6, CsGH3.9, CsGH3.10, CsIAA26, CsIAA33, CsSAUR50, and CsSAUR41 in bud dormancy regulation in tea plant. Our results validate the important role of auxin in tea plant dormancy regulation and provide useful information for further functional studies.