• 作者： 徐世典; 蔡東纂; 曾國欽
• 作者服務機構： 國立中興大學植物病理學研究所
• 中文摘要： 由臺灣各地不同寄主植物分離而得的青枯病菌50個菌株，在供試番茄上的病原性都很強，都屬於感染多種茄科植物的 race 1，但依其在6種寄主上的病原性差異，可區分為8個菌系。大多數菌系對馬鈴薯亦有強病原性，但在茄子、甜椒、煙草及落花生上的病原性，因菌系的不同而有顯著差異。以番茄10種品種測定的結果得知，青枯病菌在番茄上有病原性強弱的不同，但無病原分化性，即無生理小種之區分。 病原菌系1,2,3及5對煙草有強病原性，而病原菌系4,6,7及8則隨病原性弱或無病原性。這兩類菌系在煙草內交互作用的結果，能影響青枯病的發生程度。對煙草無病原性的菌系（如65號菌株）與有病原性的菌系（如21菌株）混合接種於煙草莖部或根部，或混合於土壤中時，病害程度減輕或不發生，而且有病原性的菌系在煙草植株內的增殖也受到抑制。此種抑制能力發生在混合接種源中無病原性菌系的濃度相同或高於有病原性菌系的濃度時；再者，無病原性菌系必須先於或同時與有病原性菌系作用在同一部位或相近的部位才能發生抑制作用。無病原性菌系在煙草葉片引起過敏性反應，當大多數無病原性菌系與有病原性菌系混合接種於葉片時，也能阻止由後者所引起的感病性反應之發生。根部接種試驗，得知這兩類菌系對煙草根部的侵入能力相同，兩者在培養基上亦無拮抗現象，因此無病原性菌系抑制有病原性菌系的致病作用僅在生體內產生，可能由於無病原性菌系所誘導的寄主過敏性反應，限制了有病原性菌系在植株內的進展與繁殖。
• 英文摘要： Fifty isolates of Pseudomonas solanacearumcollected from various hosts in many areas ofTaiwan were compared for their pathogenicityon host plants. Based on reactions of 6 hoststo these isolates, 8 strains (pathovars) belongingrace 1 were recognized. All strains were ofhigh virulence to tomato and most strainswere also highly virulent to potato, but strainsdiffered considerably in virulence to eggplant,sweet pepper, tobacco and peanut. Ten selectedisolates representing various strains of thebacterium also differed in virulence whentested on 10 tomato varieties. Physiologic raceswith distinctly contrary on tomato varieties didnot seem to exist among the strains. Interaction between various strains that dif-fer in pathogenicity to tobacco was studied intobacco plants. Severity of bacterial wilt wasmarkedly reduced when tobacco plants wereinoculated with a suspension containing mixtureof a strain virulent to tobacco (V strain) and astrain avirulent to tobacco (AV strain) by thesteM-puncture, root-dipping, and soil-infestationinoculation methods. The growth of the V strainwas also reduced in plants inoculated with mix-tures of both strains. The reduction in diseaseseverity occurred when the proportion of cellsof AV strain to V strain was equal or more.The effect was evident only when both strainswere simultaneously introduced or AV strainwas introduced prior to V strain into the sameposition of the plants. Root inoculation testindicated that these strains penetrated readily toroot tissues when they were mixed in the in-oculum. Susceptible reaction (wilting) caused byV strains in tobacco leaves was also inhibitedby the association with most AV strains. SinceAV strains were not antagonistic to V strainsin vitro, the effect on disease reduction waspresumably mediated through host response,possibly by the hypersensitive reaction of hostinduced by AV strains.
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