Multi-dimensional regulation of tea leaf development: morphogenesis, hormone-transcriptional networks, environmental...

Tea (Camellia sinensis) is an important cash crop worldwide, with leaf development directly determines the yield, quality and economic value of tea products. Tea leaf formation is mainly controlled by a four-dimensional integrated regulatory framework. Specifically, leaf morphogenesis provides the structural basis, endogenous hormone-transcription factor networks form the core regulatory hub, environmental signals (e.g., light, temperature, water, altitude, pests, and diseases) provide the external driving force, and artificial cultivation practices enable precise human intervention. These four dimensions synergistically modulate leaf morphological structures, physiological functions, and secondary metabolite accumulation throughout the developmental cycle. Despite recent advances in research on individual regulatory factors, the cross-talk between multi-dimensional factors and the core regulatory nodes affecting leaf development remain poorly elucidated. Moreover, a comprehensive review integrating multi-scale regulatory mechanisms is still lacking. This article provides a comprehensive overview of tea leaf development in terms of these four dimensions. Furthermore, key research gaps (compared with the research on model crops and other horticultural crops) are described, while future research directions in this field are discussed. This review provided herein offers a theoretical basis for improving tea varieties and developing efficient cultivation practices.