Abstract:

The germplasm resources of Lagerstroemia are extremely rich，including various natural species and cultivated varieties. Based on this，this article comprehensively reviews the research progress of the germplasm of Lagerstroemia and cross breeding，focusing on analyzing the research results of intraspecific hybridization and distant hybridization，the occurrence mechanism and coping strategies of hybridization barriers，and the identification techniques of hybrids. There are 65 recorded species of Lagerstroemia. Utilizing these abundant resources，breeders from various countries have cultivated a large number of different types of varieties. However，the vast majority are derivatives of L. indica or interspecific hybrids of L. indica and L. fauriei，or L. indica and L. limii. Although the interspecific hybridization between L. indica and L. speciosa，and between L. indica and L. caudata is compatible，the hybrid descendants of the former are sterile and cannot be backcrossed；for the latter，only one hybrid variety between the two has been obtained so far. For the remaining interspecific or intergeneric hybrids of Lagerstroemia，there are pre-fertilization or post-fertilization barriers. To solve these problems，researchers have successfully obtained a small number of distant hybrid descendants through techniques such as spraying 2,4-D on the stigma after pollination or embryo in vitro culture. Cross breeding is the main method for cultivating new varieties of Lagerstroemia at present，with the release of genomic data such as that of L. indica and L. speciosa，it is expected that through the mining and analysis of genomic data，the directional improvement of the ornamental traits of Lagerstroemia can be achieved through gene editing technology in the future，thereby rapidly cultivating new varieties of Lagerstroemia with excellent traits.

Key words: Lagerstroemia, germplasm, hybrid breeding, cross-incompatibility, hybrid identification