石河子市区大花金鸡菊白粉病病原鉴定及发病规律

Pathogen Identification and Occurrence Regularity of Powdery Mildew of Coreopsis grandiflora in Shihezi

【目的】研究新疆石河子地区大花金鸡菊白粉病的病原种类,逐步摸清其发病规律。【方法】采用显微形态观察结合分子生物学方法对其病原进行鉴定,并系统调查病害的季节流行动态。【结果】金鸡菊白粉病菌分生孢子大小为24.4~34.2μm×14.6~22.0μm,以2~4个分生孢子串生在分生孢子梗上,闭囊壳球形,直径平均为115.1μm,闭囊壳内单子囊,子囊椭圆形、无色且有柄,大小为68.3~131.7μm×56.1~80.5μm,子囊内8个子囊孢子,大小为14.6~26.8μm×12.2~21.7μm,附属丝菌丝状。根据病原菌的rDNA-ITS序列(563 bp)建立发育树,其与Podosphaera fusca(登录号KM225763、JX546297、KR049083和MF476989)聚在1个进化支上,且序列同源性99.0%以上。【结论】棕丝单囊壳(Podosphaera fusca)为石河子市区大花金鸡菊白粉病的病原菌,且该病害在石河子地区4月中上旬始发,6月中下旬达到发病高峰期,7月初开始进入衰退期。

【Objective】To identify the pathogenic species and explore dynamic epidemic of Coreopsis grandiflora powdery mildew in Shihezi area.【Method】Morphological and molecular approaches were adopted to identify the pathogen of Coreopsis grandiflora powdery mildew,and dynamic of disease epidemic was systematically surveyed.【Result】The results showed that the conidiophores were up-right and producing 2-4 conidia in chains.Conidia were 24.4-34.2μm×14.6-22.0μm,Chasmothecia were dark brown,spherical,115.1(96.3-139.0)μm in diameter.Chasmothecium contained one asci with eight ascospores.Asci were sessile,broadly ellipsoid-ovoid to subglobose,68.3-131.7μm×56.1-80.5μm.Ascospores were 14.6-26.8μm×12.2-21.7μm.Appendages were mycelioid.The internal transcribed spacer(ITS)region of rDNA of the fungus was amplified and sequenced.The resultant 563 BP sequence was produced.A GenBank BLAST search of the China and Korea isolates showed above 99.0%similarity with Podosphaera fusca(Accession numbers are:KM225763,JX546297,KR049083 and MF476989).【Conclusion】Therefore,the pathogen causing powdery mildew of Coreopsis grandiflora was identified as Podosphaera fusca.The disease began in the middle of April,reached its peak in late June,and began to decline in early July in Shihezi of Xinjiang.