A Class II TCP Transcription Factor PaTCP4 from Regulates Trichome Formation in .

London plane tree is widely grown as a landscaping and street tree, but the release of its trichomes creates a serious air-borne pollution problem. Identifying the key genes that regulate the development of trichomes is, therefore, an important tool for the molecular breeding of . In this study, a sequence homologous with the Arabidopsis Class II TCP subfamily was identified from London plane, and named . The expression of was detected in various organs of London plane trees, significantly in the trichomes. Overexpression of in Arabidopsis reduced the trichome density on the first pair of true leaves, and atypical 5-branched trichomes were also detected on those leaves. The expression of endogenous and was significantly increased in transgenic lines, and was associated with a decrease in the expression of endogenous . Furthermore, the expression of endogenous was significantly increased. In addition, the protein product of was shown to directly activate , , , , , and in yeast one-hybrid assays and in the dual-luciferase reporter system. Taken together, these results identify a role for in trichome initiation and branching in Arabidopsis. Thus, represents a strong candidate gene for regulating the development of trichomes in London plane trees.