WD40 proteins PaTTG1 interact with both bHLH and MYB to regulate trichome formation and anthocyanin biosynthesis in Platanus acerifolia.

Trichome development and anthocyanin accumulation are regulated by a complex regulatory network, the MBW complexe consists of MYB, bHLH, and WD40 transcription factors. In this study, two sequences, named PaTTG1.1, and PaTTG1.2, were cloned and functionally characterized from Platanus acerifolia. Quantitative real-time PCR results showed that PaTTG1 genes were expressed in the trichomes and red leaves. Overexpression of PaTTG1.1 and PaTTG1.2 genes in Arabidopsis ttg1 mutants restored the phenotypes of ttg1 mutants that were glabrous and lacked purple anthocyanins in hypocotyls and seeds. In transgenic plants, the expression levels of the trichome regulation-related genes AtCPC, AtTRY, AtETC1, AtMYB23, and AtGL2, as well as early and late biosynthetic genes related to anthocyanin biosynthesis, were significantly upregulated. The results of the yeast two-hybrid showed that PaTTG1.1 and PaTTG1.2 proteins could physically interact with both bHLH and R2R3-MYB transcription factors from Arabidopsis and P. Acerifolia. Taken together, the results presented in this study suggest that the two PaTTG1 genes share similar functions in the regulation of trichomes and anthocyanins. However, there may be some differences in their regulatory mechanisms.