萵苣萎凋病菌的病原性測定

Pathogenicity Tests of Lettuce Fusarium Wilt Fungus

彭玉湘(Y. H. Peng) ； 黃振文(J. W. Huang)

《植物病理學會刊》 7卷3期 (1998/09) Pp. 121-127

https://doi.org/10.6649/PPB.199809_7(3).0001

摘要

近年來在萵苣(Lactuca sativa)栽培田中，發現菜苗大量死亡，導致萵苣田局部缺株的現象；此外，罹病的植株呈現矮化、萎凋、葉片黃化壞疽、根莖維管束褐變及支根數目減少等病徵。由罹病株分離到的Fusarium. oxysporum菌株，重新接種於萵苣，兩星期後植株出現如在田間相同的病徵，隨後將具病原性的F. oxysporum分別接種於萵苣、白菜、蘿蔔、豌豆、番茄、瓜類、菠菜、芹菜等作物及不同種菊科植物，結果發現僅有萵苣受感染。此外，將萵苣、蘿蔔、香蕉、百合、苦瓜、西瓜及茼蒿等萎凋病菌的F. oxysporum分化種菌株，分別接種於萵苣植株，結果只有來自萵苣的F. oxysporum可感染萵苣，因此確定萵苣萎凋病係由具有專一性之F. oxysporum f. sp. lactucum引起。本菌在PDA(Potato dextrose agar)培養基上的菌落有兩種，其一產生乳黃色孢子堆之藍紫色菌落，其二則產生橘黃色孢子堆之粉紅紫色菌落，兩者均有三型的孢子：小孢子為單孢，橢圓或臘腸形，無色，大小3.8~11.4×2.0~3.8μm(平均6.8×2.1μm)；大孢子為鐮刀形，無色，大小17.8~36.1×3.8~5.7μm(平均26.5×4.4μm)，1~4個隔膜(大多3個隔膜)；厚膜孢子近圓形，無色，大小5.7~11.4×5.7~11.4μm(平均9.3×7.2μm)。本菌生長溫度範圍為12~32C，菌絲最適生長溫度為20~24C。探討萵苣品種對本菌的抗感病反應，發現結球、皺葉與白葉萵苣對本菌兩供試菌株，呈現不同程度的抗感病反應，其中嫩莖萵苣的抗病性最高。

關鍵字

萵苣 ； 萵苣萎凋病 ； 病原性 ； 寄主範圍

並列摘要

A new wilt disease of lettuce (Lactuca sativa L.) was found in Taiwan in 1996. The disease is characterized by the death of some plants in the seedling stage. Older infected plants severely stunted and wilted. Inner tissues of infected plants appeared brown in the vascular system, accompanied by epinasty and yellowing of leaves. Discolored vascular streaks in yellowing leaves were extended from the root. Fusarium oxysporum was consistently isolated from all infected plants. In greenhouse inoculations, this fungus caused a wilt disease of lettuce. However, it did not do any symptom in other crops including composite species. For specific pathogenicity to lettuce, the fungus was named F. oxysporum f. sp. lactucum. Two morphological types of the pathogen appeared on potato dextrose agar during they were cultured. One type of the isolates produces the blue-purple colony with buff-yellow sporodochia. Another type of the isolates produces peach-purple colony with orange sporodochia. Microconidia produced abundantly from monophialides on potato dextrose agar (PDA); one-celled, hyaline, elliptic, or ovoid; 3.8~11.4×2.0~3.8μm. Macroconidia produced on PDA; hyaline, sickle-shaped; 1~4 septates; 17.8~36.1×3.8~5.7μm. Chlamydospores spherical to ovoid, smooth-surfaced, terminal or intercalary; 5.7~11.4×5.7~11.4μm. The optimum temperatures for mycelial growth of F. oxysporum f. sp. lactucum isolates LFO 11-13 and LFO 32-14 were at 24~28℃. Susceptibility of some lettuce cultivars to isolates LFO 11-13 and LFO 32-14 was significantly different. Among tested eight cultivars of lettuce, the celtuce (celia) cultivar was the most resistant to the disease.

並列關鍵字

Lettuce ； Fusarium wilt ； host range