Breeding and application of high-quality, multi-resistant restorer line Guihui 581 and identification of superior alleles

【Objective】The study aimed to breed the high-quality, multi-resistant restorer line Guihui 581, and to identify its superior alleles, in order to provide references for developing new high-quality, multi-resistant rice varieties using the superior genes from the heterologous tetraploid wild rice, Oryza minuta. 【Method】Using IR24 as the female parent and O. minuta as the male parent, backcrossing and selfing were performed, combined with marker-assisted selection（MAS） and resistance identification against rice blast disease and rice planthoppers in the field. Superior restorer lines were selected from O. minuta introgression lines, which were then cross-tested with male sterile lines including Huazhe 2A, Fengtian A, Tianfeng A, and Longfeng A to evaluate the restorative capacity of Guihui 581. Additionally, the pentaprimer amplification refractory mutation system（PARMS） technology was employed to detect the predominant disease and insect resistance genes and rice quality genes carried by Guihui 581, Huazhe 2A and Huazheyou 581. 【Result】A total of 371 introgression lines from O. minuta were obtained, among which the agronomically consistent material R981 was selected. Through further generation advancement and purification, a strong and superior restorer line Guihui 581 was bred. In 2018, Guihui 581 was granted plant new variety right（registration number: CNA20171712.4）. Guihui 581showed a resistance level of 3.7 to rice planthoppers and a comprehensive resistance index of 5.0 to rice blast. The combinations involving the restorer line Guihui 581 presented good plant architecture, high seed setting rate, and strong heterosis. Among them, the Huazhe 2A/Guihui 581 hybrid combination Huazheyou 581 was selected as a test variety due to its strong adaptability, moderate reproductive period, vigorous development, good late ripening color, high yield, fine rice quality, and strong resistance. From 2019 to 2020, Huazheyou 581 participated in the regional trials of photosensitive late indica rice in the rice growing areas of southern Guangxi, and was approved by the Guangxi Crop Variety Approval Committee in June 2022（approval number: Guishen Rice 2022149）. PARMS test unveiled that Guihui581 carried blast resistance genes Pi5, Pi54, Pib and Pia, and superior rice quality alleles GS2, GS3, GS5, GL7, GW5 and Chalk5. In comparison, Huazhe 2A harbored blast resistance genes Pita, Pi54, Pib and Pi46, bacterial blight resistance gene Xa7, rice planthopper resistance gene Bph15, and rice quality genes GS2, GS3, GS5, GL7, GW5, fgr, ALK and Chalk5.【Conclusion】Using the resources of O. minuta, Guihui 581 has been successfully developed, characterized by high yield, wide adaptability, and strong stress resistance. It may carry new resistance genes against rice planthoppers and can be used as a high-quality, multi resistant restorer line in hybrid rice breeding. Additionally, the new hybrid rice variety Huazheyou 581 was bred, which not only enriches the types of rice varieties, but also serves as a reference for the development and utilization of wild rice resources in China.