Abstract: This review focuses on leaf color mutants of medicinal plants, systematically expounds their induction pathways, mutation molecular mechanisms and characteristic applications, and highlights the research value of medicinal plants in secondary metabolism regulation. Leaf color mutants are mutation types in which gene mutations cause abnormalities in chlorophyll synthesis or degradation, thereby changing leaf color. They can be classified according to seedling leaf color, pigment content, genetic characteristics, etc. Their induction methods are divided into spontaneous mutation and artificial induction mutation, and the latter covers physical, chemical and biological mutagenesis, each with its own advantages and disadvantages. In terms of molecular mechanisms, mutations in key genes for chlorophyll synthesis and degradation lead to pigment metabolism imbalance, abnormalities in chloroplast development genes affect chloroplast structure and function, variations in photosynthesis genes change the efficiency of light energy capture and conversion, and transcription factors and light signal/hormone pathways synergistically regulate leaf color. Especially in medicinal plants, leaf color mutations are often accompanied by changes in photosynthetic efficiency. Through energy supply, carbon-nitrogen allocation and metabolic precursor sharing, the "chlorophyll metabolism-secondary metabolism" network is reshaped to regulate the synthesis and accumulation of medicinal secondary metabolites such as flavonoids, terpenoids and alkaloids. Therefore, leaf color mutants are not only tools for analyzing photosynthetic and chloroplast development mechanisms, but also key materials for mining the regulatory network of medicinal component synthesis, and have broad application prospects in functional genomics research, molecular marker-assisted breeding and the creation of medicinal germplasm with high active ingredients. Although current research has achieved certain results, it still faces problems such as low efficiency in mutant screening, unclear functions of some genes, and insufficient integration of multi-omics data. In the future, relying on technological innovations such as CRISPR gene editing, combining multi-omics integration and artificial intelligence screening, we should focus on breaking through the light regulation mechanism of medicinal component synthesis and promoting the genetic improvement of endangered species and the cultivation of high-active varieties.

Key words: secondary metabolism, medicinal plants, leaf color mutants, molecular mechanism, mutagenesis method