The Biosynthesis of Main Taste Compounds Is Coordinately Regulated by miRNAs and Phytohormones in Tea Plant (Camellia sinensis)

Based on the abundance of taste compounds in leaves at different leaf positions on the same shoot, green tea made from one bud and one leaf, or even just one bud, has the best quality. To elucidate the mechanism underlying the regulation of the biosynthesis of these compounds, we profiled the metabolome, transcriptome, sRNA, degradome, and WGCNA using leaves from five leaf positions of shoots. Through this analysis, we found 139 miRNA-target pairs related to taste compound biosynthesis and 96 miRNA-target pairs involved in phytohormone synthesis or signal transduction. Moreover, miR166-HD-ZIP, miR169-NF-YA, IAA, ZA, ABA, and JA were positively related to the accumulation of gallated catechin, caffeine, and theanine. However, miR396-GRF, miR393-bHLH, miR156-SBP, and SA were negatively correlated with these compounds. Among these important pairs, the miR396-GRF and miR156-SBP pairs were further validated by using qRT-PCR, Northern blots, and cotransformation. This is the first report describing that miRNA-TF pairs and phytohormones might synergistically regulate the biosynthesis of taste compounds in the leaves of tea plants.