合欢枯萎病菌的分离鉴定和培养特性

Identification of Fusarium pathogens of Albizia julibrissin wilt and their cultural characteristics

以安徽省合肥市长岗镇20份合欢枯萎病株样品为对象,采用组织分离法纯化枯萎病菌并进行形态学和分子生物学特征鉴定,进而考察不同培养条件如碳源、氮源、pH和温度对病菌生长的影响。研究获得7株致病镰刀菌(Fusarium),将菌株3和3-1鉴定为木贼镰刀菌(F.equiseti),4和10为尖孢镰刀菌(F.oxysporum),1-2和3-2为腐皮镰刀菌(F.solani),2-3为层出镰刀菌(F.proliferatum)。致病力测试结果表明,F.oxysporum对合欢枝条的致病力较强,而F.solani、F.equiseti和F.proliferatum致病力弱。培养研究发现,病菌最适生长温度为28～32℃;F.proliferatum在pH=9时生长最快,其他菌株的最适pH为7.0;F.solani、F.proliferatum和F.equiseti能较好地利用蔗糖和乳糖,F.oxysporum在葡萄糖、蔗糖和乳糖培养基上生长较好;各菌株在含硝酸铵的培养基中菌落直径最大,而草酸铵对病菌生长不利。结果可为合欢枯萎病害的诊断和防治提供理论依据。

Twenty samples of Albizia julibrissin wilt plants were selected as objects from Changgang, Hefei in Anhui Province, tissue isolation was used and identification was performed on morphological and molecular features, influence of different culture conditions including carbon, nitrogen, pH and temperature on the growth of pathogens were also investigated. Seven strains of Fusarium spp. were obtained and identified as F. equiseti(3 and 3-1), F. oxysporum(4 and 10), F. solani(1-2 and 3-2) and F. proliferatum(2-3), respectively. Pathogenicity tests on the branch showed that F. oxysporum was highly pathogenic strain,while F. solani, F. equiseti and F. proliferatum were weak pathogenic strains. Cultural studies indicated optimum temperature and pH were 28-32 ℃ and 7, respectively, while F. proliferatum could grow faster in pH=9. Sucrose and lactose could be used by F. solani, F. proliferatum and F. equiseti among tested carbons and the optimal carbons of F. oxysporum were glucose, sucrose and lactose. Colony diameters of Fusarium spp. were biggest when ammonium nitrate was used as nitrogen source, and smallest when ammonium oxalate was used as nitrogen source. This study would provide a theoretical basis for the diagnosis and control of Albizia julibrissin wilt.