Xanthomonas oryzae pv. oryzicola 引起的水稻細菌性條斑病

Abstract

2007年在南投縣草屯鎮及雲林縣二崙鄉田區水稻陸續出現暗綠色至黃褐色條斑的病徵，條斑上有時可見細小的黃色菌泥，後來陸續在苗栗、台中、彰化、嘉義、台南、花蓮和台東等地發現相同的病徵，從條斑處可分離出黃色細菌，菌落型態類似白葉枯病菌，經柯霍氏法確定此黃色細菌為病原，經過16S rDNA定序比對，結果顯示此病原細菌與水稻白葉枯病菌Xanthomonas oryzae pv. oryzae（Xoo）相似度高達97%，與Xanthomonas oryzae pv. oryzicola（Xoc）相似度達100%，此病原細菌接種至供試水稻品種上皆造成條斑狀病徵，不同於白葉枯病菌造成的典型葉枯型病徵，且生理生化試驗測定結果得知該細菌可利用L-Alanine，但無法生長在含有Cu(NO_3)_2的培養基中，確認該病原細菌為X. oryzae pv. oryzicola，可引起水稻細菌性條斑病。 In 2007, a new disease of rice was found in Nantou and Yunlin Counties in Taiwan. The symptoms exhibited dark-green to light brown translucent streak on rice leaf, and bacterial oozes appear on the lesions under humid conditions. This disease was later found in Miaoli, Taichung, Changhua, Chyayi, Tainan, Huailien, and Taitung Counties in Taiwan. Results from 16S rDNA sequencing and comparison revealed that the nucleotide sequences shared 97% similarity with the ones of ＂Xanthomonas oryzae pv.＂ oryzae (Xoo), and 100% similarity with ＂Xanthomonas oryzae pv. oryzicola＂ BLS256. Based on the symptoms and pathological studies, 16S rDNA sequencing, and physiological and biochemical analyses, the pathogen was identified as ＂Xanthomonas oryzae pv. oryzicola＂ (Xoc). The susceptibility of rice cultivars to bacterial leaf streak (BLS) were tested in greenhouse.