水稻抗病單基因系及堆疊品系之選育與應用

Abstract

病害是水稻生長過程中重要的限制因子，若發生嚴重會導致產量損失，並對糧食安全造成威脅。稻熱病、白葉枯病及徒長病為重要的水稻病害，在各種防治方法中，使用抗病品種被認為是有效、經濟且環保的方式。抗病品種若只帶有單一主效抗病基因，對於田間病原菌的菌株之抗性不夠持久，且抗性只侷限於單一病害。本研究以多系品種及基因堆疊兩策略，期望增加田間抗病基因多樣性，藉此延長抗病品種的田間抗性，並擴增其抗性幅度。本研究於2021-2023年以帶有不同抗病基因的高雄145號單基因系KHY5508 (Pi9)、KHY5496 (Pik-h)、KHY5491 (Ptr) 進行田間混植試驗，結果顯示混植品系對於葉稻熱病及穗稻熱病皆具有良好抗性，且其農藝性狀與米質亦與高雄145號相似。本研究同時以高雄145號單基因系作為親本，透過分子標誌輔助選拔，將Pi9、Pik-h、Ptr分別導入高雄147號中，選出7個抗性及農藝性狀皆優良之BC4F4單基因系；建立帶有Pi2、Pik-h、Ptr之高雄145號三基因堆疊品系，選出5個性狀優良之品系；將部分抗性基因gene pi21導入帶有Pi9、Pik-h、Ptr之基因堆疊品系KHY5697，降低主效基因被克服之風險。本研究亦建立以臺稉16號及台農71號為背景，帶有抗稻熱病基因Ptr、抗白葉枯病基因Xa4、xa5、Xa21及抗徒長病QTLs qBK1.8、qBK2.1的堆疊品系。本研究所選育具有優良農藝性狀之抗病品系，未來有機會推廣種植，亦可作為其他抗病育種計畫的親本，加速育種流程。

Disease is an important limiting factor in rice production. It may cause yield loss, threatening food security. Rice blast, bacterial blight, and bakanae disease are important rice diseases. Among various control measures, the use of resistant varieties is considered effective, economical, and eco-friendly. However, a disease-resistant variety carrying a single major-effect resistance gene may not provide durable field resistance to the pathogen, and the resistance is limited to a single disease. This study aims to increase the diversity of resistance genes in the field with the strategies of multiline varieties and gene pyramiding, hoping to prolong field resistance of resistant varieties and broaden their resistance spectrum. In 2021 to 2023, a mixture of three rice Kaohsiung 145 (KH145) monogenic lines carrying different R genes, KHY5508 (Pi9)、KHY5496 (Pik-h)、KHY5491 (Ptr), were tested in the field. The mixture showed good leaf and panicle blast resistance and similar agronomic traits and rice quality to KH145. Using KH145 monogenic lines as resistance donors and marker-assisted selection, Pi9, Pik-h, and Ptr were introduced into rice Kaohsiung 147 (KH147), and seven BC4F4 monogenic lines with excellent resistance and agronomic traits were selected; KH145 three-gene pyramided lines carrying Pi2, Pik-h, and Ptr were developed, and 5 lines with excellent traits were selected; to reduce the risk of major-effect genes being overcome in the field, partial resistance gene pi21 was introduced into KHY5697 (carrying Ptr, Pik-h, Pi9). This study also developed a multi-disease resistant line carrying rice blast resistance gene Ptr, bacterial blight resistance genes Xa4, xa5, Xa21, and bakanae disease resistance QTLs qBK1.8 and qBK2.1 in the backgrounds of rice Taikeng 16 and Tainung 71. The disease-resistant varieties bred in this study have excellent agronomic traits and may be promoted for planting in farmers’ fields. They can also be used as resistance donors for other breeding programs to accelerate the breeding process.