Developing partial interspecific hybrids of Momordica charantia × Momordica balsamina and their advance generations

Interspecific hybridization and introgression breeding are the major approaches employed to address climate change and food security challenges globally. The present study was conducted to trace the nature of crossing barriers and to introgress novel genes from Momordica balsamina to cultivated bitter gourd Momordica charantia. The hybridization success rate was very low between these two species with a higher rate of seedling mortality. A total of 116 accessions of Momordica charantia (female parent) were used for artificial cross-pollination with Momordica balsamina (IC-467683). Among these, only six female parents belonging to Momordica charantia (DBGS-2, NEH-4, PDMGY-201, Pusa Aushadhi, DBGS-3, and NEH-3) exhibited variable percent fruit set when crossed with Momordica balsamina. Among these interspecific crosses, only one cross combination (Pusa Aushadhi × Momordica balsamina) produced the higher percentage of normal seeds and only one seed was germinated followed by development into a full plant. The pollen-pistil interaction study confirmed the existence of post dynamic barriers in all these unsuccessful crosses. A single plant progeny of M. charantia × M. balsamina was derived and its advanced generations were studied at morphological, cytological, and molecular levels. The plant phenotype predominately resembled the female parent with variation in a few traits. The cytological analysis depicted the normal meiosis and the genomic 2C DNA content of the interspecific hybrid was higher than the female parent. The microsatellite (SSRs) markers analysis showed that amplified fragments of interspecific hybrids exhibited highly conserved similarity with fragments of female parents with a very low frequency of male fragments. The F2 and backcross generations were produced from the single partial interspecific hybrid (Pusa Aushadhi × M. balsamina). Twenty advanced generation F2 plants showed variation with majority traits resembles the female parent. The microsatellite analysis revealed that the progenies of backcross generation amplified the fragments with high similarity to both female (Pusa Aushadhi; M. charantia) and the male parent (M. balsamina). These results confirmed the partial introgression of chromosome segments of M. balsamina. But further generations could not be recovered and advanced generation was died because of chlorosis. It was the first attempt to develop an interspecific partial hybrid and its backcross population which would provide preliminary information on the crossability relationship between these two species for transferring novel gene/s or traits from M. balsamina to M. charantia.