Dhaka the 9th November, 13. In an article titled, “Cytogenetic and molecular characterization of an intergeneric hybrid between Oryza sativa L. cultivar IR56 and Porteresia coarctata (Roxb.) Tateoka published recently in the IRRI Oryza sativa (2n = 24) and Poteresia coarctata (2n = 4x = 48) through embryo rescue and backcrossing. Panicles of O. sativa cv. IR56 were emasculated and pollinated with pollen of P. coarctata. Ten-14 days after pollination immature embryos were excised and cultured in the nutrient medium to obtain the hybrid seedling. Isozyme analysis was used to characterize the F1 hybrid. The hybrid was found to be slow growing and intermediate in morphological characteristics . It is completely male sterile. Starch gel electrophoresis showed IR56 and P. coarctata to be highly polymorphic. Of 20 loci, Amp1, Amp2, Amp3, Amp4, Pgi1, Pgi2, Pgd1, Pgd2, Adh1, Sdh1, Mal1, Got1, Got3, Mdh1, Mdh2, Mdh3, Est1, Est2, Est5, Est9 examined, 16 were polymorphic. The F1 showed isozyme bands from both parents indicating its true hybrid nature. Meiotic chromosome analysis of the hybrid showed 36 univalents at metaphase I indicating lack of pairing between chromosomes of O. sativa and P. coarctata. Cytogenetic and molecular analysis confirmed the true hybrid nature of the F1 showing limited homoeology.
between O. sativa and P. coarctata genomes.