Genetic Homozygosis of Resistance of Common Wild Rice (Oryza rufipogon) against Brown Planthopper

[ Objective] The stability of resistance heredity of common wild rice against brown planthopper was studied to screen wild rice germplasm with stable resistance, so as to provide resources for rice breeding with resistance against brown planthopper. [ Method] A total of 1 591 accessions of common wild rice, collected from 46 proterozoic growth locations of Guangxi, were screened to analyze resistance against brown planthopper, and genetic homozygosis in their offspring was detected using bag-selfing or anther culture methods. [ Result] The results showed that most of common wild rice germplasm were heterozygotic, and growth habit and awn of their first self-bred generation showed segregation. Among 1 591 accessions of common wild rice, only 30 accessions showed third to fifth grades of resist- ance against brown planthopper, and most of them showed fifth grade of resistance. Among selfing offspring of 11 resistant materials, the populations from Z1 to Z3 showed segregation of resistant genes, while some materials showed stable resistance in Z4. Out of 11 accessions of materials, resistance of five accessions increased from third grade to first, second and third grades; four accessions increased from fifth grade to first, second and third grades ; two accessions increased from fifth to third grade. Anther culture results showed that 125 accessions of callus from independent origins were obtained after induction by in vitro culture of 6 000 anthers; eight clusters of diploid and two clusters of haploid green seedlings were differentiated, with induction rate of callus as 2.0% and differentiation rate of green seed- lings as 6.4%. Out of eight offspring of anther culture, six showed fifth grade of resistance against brown planthopper and two showed third grade of resistance. [ Conclusion] The stable highly-resistant resources could be obtained and resistance level of common wild rice could be enhanced through bag-selfing and multigeneration identification of resistance against brown planthopper. Anther culture is beneficial to promote genetic homozygosis of resistance of common wild rice against brown planthopper and shorten the screening time.