以三種改良之評估方法判定水稻幼苗對徒長病之抗感病性

Three modified methods for evaluation of bakanae disease resistance in rice seedlings

陳思聿(S. Y. Chen) ； 黃凱均(K. J. Huang) ； 郭彥甫(Y. F. Kuo) ； 賴明信(M. H. Lai) ； 陳又嘉(Y. C. Chen) ； 鍾嘉綾(C. L. hung)

《植物病理學會刊》 24卷3&4期 (2015/12) Pp. 201-210

https://doi.org/10.6649/PPB.201512_24(3_4).0003

摘要

水稻徒長病是廣泛分布於水稻種植區域的病害，近年來在許多亞洲地區有危害增加的情形。水稻徒長病所引起的植株徒長或矮化、節間延長、纖細瘦弱或著生角加大等複合病徵，在評估時較一般病害困難。本研究設計三種改良之評估方式（人為觀察、影像分析及鑑別性培養基），運用於8個水稻品種之人工接種罹病株與健康對照組的差異判定，以瞭解該等方法之應用性。結果顯示，人為觀察配合改良之分級標準，有助於節省評估時間；以MATLAB軟體新開發之影像分析系統，可同時精細量化多項形態特徵變化；將植株基部之不同片段置於FFC鑑別性培養基上培養，可檢測病原之拓殖分布，但不同獨立實驗間變異較大。影像分析結果亦顯示，沒有任何單一項形態特徵變化足以代表本實驗中所有水稻品種之抗感病特性，故評估時宜對多項病徵表現綜合考量，而植株寬度、第2節間長、第3片葉葉長、葉片角度等4項特徵在罹病株之變化較顯著，故可能適合作為未來人為判定之觀察重點。供測之水稻品種中，Budda在三種評估方式下均最為抗病，而豐錦、高雄139、越光則各在兩種評估方式中呈現感病，相關資訊可作為抗病育種之參考。

關鍵字

判定基準 ； 影像分析 ； 罹病程度 ； 鑑別性培養基

並列摘要

Bakanae disease of rice is widely distributed in rice growing areas. In recent years, the increasing occurrence and severity of the disease has been reported in many regions of Asia. Infection with Fusarium fujikuroi leads to complex symptoms, including elongation or reduction in plant height, elongated internode, slenderness, and wide leaf angles, which make the evaluation for bakanae disease challenging. In this study, we designed three modified evaluation methods (visual rating, image analysis, and selective medium) and tested their applicability by investigating the differences between artificially inoculated and healthy plants of eight rice varieties. The results suggested that visual observation with a modified rating scale could simplify the ratings and save time. The use of a new image analysis system developed by MATLAB software helped simultaneous and accurate quantification of multiple morphological features. Cultivation of different segments, cut from the stem base of infected plants, on the FFC selective medium helped determine the colonization and distribution of the pathogen in rice seedlings; however large variations were observed among independent trials. Results from image analysis also showed that no single morphological feature could be used to represent the resistance/susceptibility of all tested rice varieties; therefore, different symptomatic characters should be considered altogether for evaluation of bakanae disease. Significant differences between the inoculated and healthy plants were generally observed for seedling width, second-internode length, third-leaf length, and leaf angle, indicating that the four morphological features may be good targets for visual rating in the future. Among the eight rice varieties, Budda showed the highest level of resistance on the basis of all three evaluation methods, whereas each of Toyonishiki, KH139, and Koshihikari showed the highest level of susceptibility by two evaluation methods. The information will be useful for resistance breeding.

並列關鍵字

Fusarium fujikuroi ； Rating scale ； Image analysis ； Disease severity ； Selective medium