Fertility analyses of interspecific hybrids between Lagerstroemia indica and L. speciosa

Abstract

Interspecific crosses play an important role in gene introgression, plant improvement and speciation. However, poor fertility of F 1 generation was commonly found, which hampered backcrossing and ideal progeny generation. To explore useful materials for further breeding programs, sterile hybrids (DD1, FD1, ZD3) from different cross combinations of Lagerstroemia indica and L. speciosa and the fertile hybrid (ZD6) were selected. The results showed that pollen grains of sterile hybrids had no germination ability while ZD6 showed 25.90% pollen germination rate. The morphology of stigmas and their papilla cells showed no apparent difference. Normal pollen tubes could be detected in ovaries of ZD6 and ZD3 24 h after pollination. However, the enlarged ovaries of ZD3 began to abscise at 72 h after pollination, which suggested that the barriers occurred during post-fertilization phases. As a consequence, ZD6 can be used as either male or female parent for further Lagerstroemia breeding programs, while the sterile hybrids may be used as female parent through embryo rescue culture.