Abstract:
Tropical recalcitrant plants refer to tropical plants that exhibit significant resistance to in vitro culture and genetic transformation, with their breeding improvement being limited by low regeneration efficiency and strong genotype dependence. Recent advances in CRISPR/Cas-based genome editing and diversified genetic transformation systems, have begun to overcome these long-standing barriers. This article systematically reviews the physiological characteristics and biological basis of regeneration obstacles in tropical recalcitrant plants, and deeply analyzes the internal mechanisms such as the restricted expression of cell totipotency, the activation of defense responses, and the imbalance of molecular regulatory networks. This paper mainly reviews the latest progress of two key transformation strategies, tissue culture-dependent and in situ transformation systems without tissue culture. Meanwhile, the article summarizes the evolution trend of gene editing delivery systems. Finally, this paper discusses the development prospects of molecular breeding of tropical recalcitrant plants, and proposes that future research should be based on the species-specific biological laws, adopt targeted technical strategies, and pay attention to the coordinated application of multiple technical routes.