PROBLEMS AND PROSPECTS FOR UTILIZING PORTERESIA-COARCTATA IN RICE BREEDING PROGRAMS

Porteresia coarctata (2n=4x=48) was crossed both as male and female pa rent with wild and cultivated diploid and wild tetraploid rice species . Hybridization was successful when P. coarctata was crossed as female parent using multiple and delayed pollinations with pollen obtained f rom tetraploid wild rice species. However, the resultant hybrid plant was very slow growing. Reciprocal crosses, using P. coarctata as male parent with wild rice species were not successful due to floret shatte ring problem. When rice cultivars were used as female parents, early a nd multiple pollinations proved successful. The hybridity of these pla nts could not be established through mitotic cytology. Polyacrylamide gel electrophoresis (PAGE) analysis for isozymes Esterases (Est) and G lutamate oxaloacetate transaminase (Got) clearly differentiated the F1 hybrid of P. coarctata x O. punctata from parents. Also, PAGE analysi s made on some of the selfed progenies of F1 hybrids between rice cult ivars and P. coarctata detected variation in the intensity of one majo r band that was different from the female parent. Because plants of th ese progenies were apparently like the maternal parent they were presu med to be resulted from fusion of haploid gametes, stimulated by the p ollen of P. coarctata. This phenomenon is known as matromorphy. The si gnificance of matromorphy in breeding programs is discussed.