Genome-based identification and analysis of the genes involved in auxin biosynthesis and signal transduction during tea plant leaf development

Auxin plays crucial roles in the process of plant growth and development. Among all the organs of the tea plant, the leaves are the main edible part for humans. The appearance and endoplasm of tea leaves directly affects taste, quality, and economic value. The metabolism of Indole-3-acetic acid (IAA) in tea plants changes the growth and development of leaves in certain aspects. However, the molecular mechanism of IAA metabolism during the growth and development in tea leaves remains unclear. To explore the molecular mechanism of IAA metabolism in tea leaves, the samples were collected from the three different development stages of tea leaves. Cell morphology and IAA contents were also investigated during tea leaves development. A total of 16 genes involved in IAA biosynthesis and signal transduction pathways were identified based on the genome sequence of Camellia sinensis. CsTSA, CsIAA27, CsTIR1 and CsCH3-6 expression patterns exhibited positive correlation with IAA concentration in tea leaves. In contrast, CsYUC1, CsCYP83B1 and CsLAX1 transcriptions were negatively correlated with IAA contents during tea leaves ripening. The interaction of IAA metabolism related proteins was also discussed. The results indicated that the growth and development of tea leaves could be regulated by IAA metabolism in the form of related-genes differentially expression and protein-protein interaction. This study provided a further glimpse to IAA metabolic pathways in leaf during tea plant growth and development.