水稻高雄145號單基因系之稻熱病抗性監測與多品系栽培應用

Application of Kaohsiung 145 monogenic lines in rice blast resistance monitoring and multiline cultivation

由Pyricularia oryzae (syn. Magnaporthe oryzae)引起的稻熱病為臺灣水稻第一期作最重要的病害，嚴重時會導致產量損失，並威脅糧食安全。種植抗病品種是有效、經濟且環保的防治策略，但稻熱病菌族群演化快速，帶單一抗病基因的品種在大面積種植後，其抗性容易在數年內被克服，故持續針對抗病基因進行監測，並發展能穩定維持田間抗性的栽培模式至關重要。本研究於2021年至2024年在嘉義及臺東稻熱病水田病圃針對帶有Pi2、Pi9、Pik、Pik-h、Pi1、Pi7、Ptr (=Pita-2)、Pi20等抗病基因的高雄145號單基因系進行葉稻熱病、穗稻熱病抗性監測，結果顯示Pi2、Pi9、Ptr之抗性最優異，Pi20、Pik-h及Pi1次之，Pi7及Pik則抗性較差，整體趨勢與往年相同。挑選抗性及農藝性狀皆良好的臺大高雄1號(Pi9)、KHY5496 (Pik-h)、KHY5491 (Ptr)，於2021年在高雄大寮與美濃、2022年在臺東關山及2023年在屏東長治進行田間混植試驗，結果顯示多品系(multiline)混植田區生長均一，對於葉稻熱病及穗稻熱病皆具有良好抗性。2021年及2023年針對產量及米質進行檢測，多品系與高雄145號大致相當；在稻熱病發生較嚴重的2023年，多品系之產量、白米正常粒率、白米直鏈澱粉含量及白米味度值顯著高於高雄145號。2022年以Pi9、Pik-h及Ptr分子標誌檢測多品系田區採集之葉片樣本，發現帶Pik-h基因的葉片有23%可觀察到感病病斑，顯示田間存在能克服Pik-h抗J. Plant Med.性之菌株。本研究初步證實高雄145號單基因系以多品系方式混合栽培之潛力，未來將持續進行單基因系之抗性監測，作為後續抗病育種及品種輪替之依據。

Rice blast, caused by Pyricularia oryzae (syn. Magnaporthe oryzae), is the most important disease affecting rice production in the first cropping season in Taiwan. In severe cases, it can result in substantial yield losses and threaten food security. Cultivating resistant varieties is an effective, economical, and environmentally friendly control strategy. However, the rapid evolution of the P. oryzae population often leads to the breakdown of resistance in varieties carrying a single resistance gene, losing their resistance after several years of widespread cultivation. Therefore, continuous monitoring of resistance genes and developing a cultivation system that helps maintain stable field resistance are essential. From 2021 to 2024, this study investigated leaf and panicle blast resistance in Kaohsiung No. 145 monogenic lines carrying blast resistance genes Pi2, Pi9, Pik, Pik-h, Pi1, Pi7, Ptr (=Pita-2), and Pi20 in paddy blast nurseries located in Chiayi and Taitung. The results indicated that Pi2, Pi9, and Ptr exhibited the highest resistance, followed by Pi20 and Pik-h. Pi1, while Pi7 and Pik showed lower resistance. The overall trends were consistent with observations from previous years. Three monogenic lines with good blast resistance and agronomic traits, i.e. NTU-KH1 (Pi9), KHY5496 (Pik-h), and KHY5491 (Ptr), were selected for 1:1:1 mix-cultivation trials conducted in Daliao and Meinong, Kaohsiung in 2021, Guanshan, Taitung in 2022, and Changzhi, Pingtung in 2023. The multiline plots were uniform, with strong resistance against both leaf and panicle blast. Yield and grain quality evaluations in 2021 and 2023 showed that the productions from the multiline were generally similar to Kaohsiung No. 145. In 2023, when rice blast was more serious, the yield, total milled rice percentage, amylose content of milled rice (%), and palatability score from the multiline were significantly higher than those of Kaohsiung No. 145. In 2022, molecular marker analysis targeting Pi9, Pik-h, and Ptr was performed on leaf samples collected from the multiline plot. Susceptible blast lesions were observed from 23% of the Pik-h-containing leaves, indicating the presence of Pik-h-virulent P. oryzae isolates in the field. This study preliminarily confirms the potential of Kaohsiung No. 145 monogenic lines for multiline cultivation. Future efforts will focus on the long-term monitoring of the monogenic lines to establish a robust foundation for resistance breeding and varietal rotation strategies.