Genome-Wide Analysis and Expression Profiling of YUCCA Gene Family in Developmental and Environmental Stress Conditions in Tea Plant (Camellia sinensis)

The tea plant is a perennial leaf-used economical crop and cultivated all over the world. Indole-3-acetic acid (IAA) plays key roles in plant development and environmental stress. YUCCA (YUC) flavin monooxygenases are the rate-limiting enzymes of the TAA/YUC pathway, which is the most important IAA biosynthetic pathway in plants. The YUC gene family in tea plants has not been systematically studied so far. A total of 17 CsYUC members were identified from a tea plant genome database and phylogenetically classified into three subfamilies. Phylogenetic analysis showed that the CsYUC gene family is evolutionarily conserved. The physical and chemical properties, gene structures, and conserved domains were analyzed. The expression profiles of CsYUCs were analyzed on the basis of open available RNA-seq data, as well as by RNA-seq and qRT-PCR assays. Combined with previous studies, it can be concluded that YUC10 may play key roles in seed development. The results also showed that CsYUC2.1 may play important roles in the coordinated regulation of the growth of leaf buds and flower buds induced by pruning. Low temperature markedly induced the expression of CsYUC2.2, -11.8, and -11.9. Furthermore, CsYUC genes that might play key roles in the specific development stages and involve enhancing the resistance to drought and NaCl stress were screened, respectively. This study could provide a research basis for deeply studying the gene functions of the CsYUC family in the tea plant.