Functional identification of MeTCP3a transcription factor in cassava leaf development

Leaves are the primary organs of photosynthesis in green plants, and their development indirectly affects the yield and starch content of cassava storage roots. However, the regulatory mechanisms governing cassava leaf development remain unclear. In this study, we explored the function of the MeTCP3a transcription factor in cassava leaf development. Amino acid sequence alignment and phylogenetic analysis showed that MeTCP3a was closely related to the TCP4 protein in rubber (Hevea brasiliensis Muell. Arg.). Subcellular localization and protein interaction assays demonstrated that MeTCP3a was localized in the nucleus, possessed transcriptional activation ability, and could form both homodimers and heterodimers in the nucleus, indicating its properties as a transcription factor. Expression analysis showed that the relative expression level of MeTCP3a was significantly higher in mature leaves compared to other tissues. When MeTCP3a expression was suppressed using VIGS (virus-induced gene silencing) technology, cassava heart leaves exhibited curled edges and a wrinkled appearance. Further real-time quantitative PCR analysis revealed that the expression levels of downstream genes related to leaf morphological development, such as MeCUC1/2/3 and MeIAA, were also down-regulated. This result suggested that MeTCP3a might influence leaf morphological development by regulating the expression of these downstream genes. This study provides a theoretical basis for further exploring the regulatory mechanisms of TCP-like transcription factors associated with leaf growth and development in cassava.