中部地區水稻徒長病發病情形、病原檢測與抗藥性分析

Investigation of Rice Bakanae Disease in Central Taiwan: Occurrence, Pathogen Identification, and Fungicide Resistance Assay

郭建志(Chien-Chih Kuo) ； 廖君達(Chung-Ta Liao) ； 黃冬青(Don-Chin Huang) ； 陳又嘉(Yu-Chia Chen) ； 鍾嘉綾(Chia-Lin Chung)

《臺中區農業改良場研究彙報》 125期 (2014/12) Pp. 11-28

摘要

由病原真菌＂Gibberella fujikuroi＂所引起的水稻徒長病(Bakanae disease of rice)為水稻重要種子傳播病害之一，近年來在中部地區普遍發生，並呈現嚴重的趨勢。為瞭解此病害在田間的分佈情形及發生原因，本場於2012年與2013年進行相關研究。試驗內容包含調查田間育苗期與本田期發病情形，檢測稻種帶菌率與溫室播種罹病率之關係，並利用分子檢測技術輔助病原菌鑑定，同時進行徒長病菌之抗藥性測試。於轄內12處大型育苗中心自2012年收集1、2期採種田種子，共52批稻種；2013年收集1、2期採種田、原種田與原原種種子，共36批稻種。稻種帶菌率檢測方面，以台南11號、台稉9號、台稉16號與台農71號普遍帶菌；調查秧苗期與本田期之罹病率，一期作明顯高於二期作，罹病率高的水稻品種包括台南11號、台中秈10號與台稉16號。大部分育苗中心於2013年改用25.9%得克利水基乳劑進行稻種消毒，結果可降低帶菌率與秧苗罹病率皆低於1%以下，田間每500欉水稻罹病株也降至1叢以下。另檢測2012年二期原原種種子及2013年原種種子，稻種帶菌、秧苗及本田皆未檢出徒長病菌。利用半選擇性培養基鑑定形態特徵與利用真核轉譯延長因子(translation elongation factor 1-α, TEF 1-α)序列鑑定，以兩組引子對tef-1/tef-2與Fftef-F/Fftef-R進行PCR檢測，可增幅出約700 bp及350 bp之專一性DNA片段，定序後可確認為G. fujikuroi。田間共分離與鑑定徒長病菌共137株，選定42株菌株為供試菌株，進行抗藥性測試。結果顯示供試之42株菌株皆可被25%撲克拉水基乳劑1,000倍、25%撲克拉水基乳劑500倍、25.9%得克利水基乳劑2,000倍等藥劑抑制生長，後續將試驗之菌絲塊回分於不含藥劑之PDA培養基上，結果顯示以得克利藥劑2,000倍可完全殺死徒長病菌，撲克拉500倍及1,000倍僅能抑制徒長病菌之生長。顯示若稻種消毒不完全，徒長病菌仍可殘存於稻種上，並造成後續之危害。鑒於目前中部地區育苗中心稻種消毒藥劑皆已選用24.9%得克利水基乳劑，應可有效降低徒長病之發生與危害。

關鍵字

水稻徒長病 ； 半選擇性培養基 ； 稻種

並列摘要

The bakanae disease is an important rice seedborne disease. It was caused by fungal pathogen ＂Gibberella fujikuroi＂ (Sawada) Wollenweber. This disease spread in central Taiwan these years and becoming more serious. The aims of this study were to survey the occurrence of bakanae disease in rice seedling nursery and in the field nursing stage, testing the seed contamination rate caused by ＂G. fujikuroi＂ and morbidity rate of greenhouse grown seedlings, identification and detection of ＂G. fujikuroi＂ by DNA molecular markers, and fungicide resistance assay. The total sums of 52 batches of rice seeds from rice nursery centers in 2012 were collected, and 36 batches of rice seeds in 2013, in which breeder’s seed, foundation seed and certified seeds were collected. The rice seeds were collected from 12 rice seedling nursery centers in central Taiwan. The percentage of ＂G. fujikuroi＂ contamination for rice varieties Tanan 11, Taikeng 9, Taikeng 16 and Tainong 71 were more than others by using the semi-selective komada and FFC medium. The incidence of the bakanae disease of rice first cropping season was higher than rice second cropping season during rice seedling stage and in the field in survey years. Furthermore, the rice varieties Tanan 11, Taikeng 16 and Taichung Sen 10 contaminated percent of ＂G. fujikuroi＂ were more than others. The incidence of bakanae disease during rice seedling stage was below 1%, as most of seedling nursery centers had changed fungicide prochloraz to tebuconazole in 2013. The incidence of bakanae disease on rice plants was below 1 hill per 500 hills in the field. In addition, the breeder's and foundation seeds were not contaminated by ＂G. fujikuroi＂, the bakanae disease was not found in rice seedling and in the field in 2012. The study used the specific primer set ef-1 and ef-2, Fftef F and Fftef, which were designed to the known special DNA fragment (translation elongation factor 1-α, TEF 1-α) of ＂Fusarium＂ spp. and ＂G. fujikuroi＂, respectively. The result showed that 700 bp and 350 bp DNA fragment were amplified by polymerase chain reaction, with the primer set of ef-1 and ef-2, Fftef F and Fftef R, respectively. After sequencing, all strains were identified as the ＂G. fujikuroi＂. We selected 42 strains from 137 ＂G. fujikuroi＂ strains to evaluate the fungicide resistance to prochloraz and tebuconazole. Results showed that 42 ＂G. fujikuroi＂ strains could be inhibited by 25% prochloraz EW diluted 500 and 1,000 fold, 25.9% tebuconazole EW diluted to 2000 fold. However, the ＂G. fujikuroi＂ mycelium could recover on potato dextrose agar by prochloraz treatment. It was shown that rice seeds disinfected incompletely could enhance the outbreak of the bakanae disease. As most seedling nursery centers have used tebuconazole fungicide to disinfect rice seeds, it could decrease incidence of the rice bakanae disease effectively.

並列關鍵字

rice bakanae disease ； semi-selective medium ； rice seed