4个蠕虫埃斯特菌株的产孢能力及对松材线虫的侵染活力（英文）

Variation in Sporulation of Four Esteya vermicola Isolates and their Infectivity Against Pinewood Nematode

【目的】通过比较不同蠕虫埃斯特菌(Esteya vermicola)菌株的形态特征、产孢能力及对松材线虫的侵染活力,从中筛选出优良的菌株用于将来松萎蔫病生防制剂的开发和应用,为松萎蔫病的生物防治提供信息和理论基础。【方法】选择3种最常用的食线虫真菌的天然培养基(马铃薯葡萄糖琼脂、玉米粉琼脂和2%水琼脂,分别代表高碳源、弱碳源和无营养3种状态),系统地比较4个E.vermicola菌株(ATCC 74485和CNU 120806分离自亚洲,CBS 115803和CBS 100821分离自欧洲)在不同培养基上的生长状况、产孢特征和杀线虫能力,并简单分析碳源营养对E.vermicola生长、产孢和侵染力的影响。【结果】4个E.vermicola菌株的基本形态特征和对松材线虫侵染过程相同,但其菌落特征、生长速度、产孢和侵染力在不同培养基上均有许多差异。培养基营养对不同菌株的生长、产孢和线虫侵染力的影响不同,营养丰富程度与E.vermicola的生长和产孢(总孢子和新月形孢子数量)呈显著正相关(P<0.05),马铃薯葡萄糖琼脂上生长和产孢最好;而与新月形孢子的比例和线虫侵染力呈负相关,水琼脂上新月形孢子比例和线虫侵染力最高。4个菌株中,ATCC 74485的生长速度和总产孢量最大(P<0.01),但新月形孢子的数量和比例最低(P<0.01),它与CNU 120806对松材线虫的侵染力都为最低(P<0.05);而CBS 115803虽然生长较慢,但新月形孢子的数量和比例均为最高,且对松材线虫的侵染力最强(P<0.01),可在3天内杀死全部被测线虫。此外,来自同一大洲的菌株在菌落形态、生长、产孢和侵染力上具有很大的相似性,表明地理位置对E.vermicola具有一定程度的影响。【结论】与其他3个菌株相比,E.vermicola CBS 11580的生长速度虽然较为缓慢,但其产生的新月形侵染孢子的数量最多,对松材线虫的侵染力也为最高,因此可选用于未来松萎蔫病生防制剂的开发和应用。

【Objective】As one of the most serious worldwide conifer diseases,pine wilt disease caused by pinewood nematode（ PWN）,Bursaphelenchus xylophilus,has brought irreparable damages to the forest ecosystems and industries with great economic and environmental losses. Esteya vermicola is the first recorded endoparasitic fungus of PWN,has exhibited high infectivity and potential as a biocontrol agent of pine wilt disease. Through the comparison among different E. vermicola isolates in their morphological characteristics,sporulation and infectivity against PWN,the excellent isolate can be screened out and to be developed as the biocontrol agent of pine wilt disease. This work will provide useful knowledge and information for the biocontrol of devastating pine wilt disease in the future.【Method】Four E. vermicola isolates（ ATCC 74485 and CNU 120806 from Asia,CBS 115803 and CBS 100821 from Europe） were compared systemically in terms of the growth,sporulation and infectivity against PWN with three most commonly used nature culture media for the nematophagous fungi（ potato dextrose agar,corn meal agar and 2% water agar,served as an example ofcarbon nutrition-rich,-weak and-poor culture media,respectively）. In addition,the influences of carbon sources on the growth,sporulation and infectivity of four isolates also were simply analyzed.【Result】Four E. vermicola isolates showed obvious variation on different culture media in terms of the colonial feature,growth speed,sporulation and infectivity,although they shared the basic morphological characteristics and nematode infection process. The nutrition of culture medium showed different influences on the growth,sporulation and infectivity of different isolates,had a markedly positive correlation with the growth and sporulation of E. vermicola,but a negative correlation with the proportion of lunate infective conidia and the infectivity against PWN. Among the four isolates,the growth speed and total conidia number of ATCC 74485 were the highest（ P〈 0. 01）,but the number and proportion of its lunate conidia were the lowest（ P〈 0. 01）,and hence had the lowest（ P〈 0. 05） infectivity against PWN in which it was the same as CNU 120806. On the contrary,although CBS 115803 showed slightly slower growth speed,it produced the biggest amount and the highest proportion of lunate infective conidia,and accordingly exhibited the highest（ P〈 0. 01） infectivity by killing all of the tested PWNs within three days. In addition,the isolates from the same continent（ Asia or Europe） shared similar characteristics in the colony morphology,growth,sporulation and infectivity,suggesting that the geographical location has an influence on E. vermicola characteristics to some extent. 【Conclusion 】Although E. vermicola CBS 115803 showed slower growth speed,it produced the biggest amount of infective conidia and exhibited the significantly higher（ P〈 0. 01）infectivity against PWN than the other three isolates did. Therefore,CBS 115803 can be selected and developed into the biocontrol agent against pine wilt disease in the future.