进境日本杜鹃中杜鹃花枯萎病菌的检疫鉴定

 自宁波口岸进境日本杜鹃花种苗上,采用常规平板分离法获得1株疑似杜鹃花枯萎病菌的菌株OV5。该菌株可在马铃薯葡萄糖琼脂和玉米粉琼脂培养基上生长,但在麦芽汁培养基上不生长。经培养可产生少量气生菌丝和大量小型分生孢子,小型分生孢子球状,直径 3.0 ~ 3.5 μm,在纺锤体状菌丝的尖端产生,易脱落,有时呈短链状。菌核卵圆形或饼形,明显杯状,凹面光滑,(1.5 ~ 6) mm × (2 ~ 8)mm × (0.5 ~ 1.5) mm,成熟时黑色。经rDNA ITS基因序列比对分析,发现该菌株与来源于CBS的2株杜鹃花枯萎病菌标准菌株的ITS基因序列同源性达99%以上,位于同一个发育分支。致病性测定结果表明,该菌株可侵染杜鹃花,引起典型杜鹃花枯萎病菌症状。上述研究结果表明,所截获病菌为杜鹃花枯萎病菌,这是我国首次截获该种检疫性真菌。

Quarantine identification of Ovulinia azaleae Weiss from the azalea of Japan

The fungal strain OV5 isolated from the azalea of Japan produced pycnidia contining conidia on PDA medium. The isolate grew well on two kinds of medium, including PDA and CMA, but not on MEA medium. The isolate usually produced little aerial mycelium and abundant spermatia. The spermatia were globose, 3.0-3.5 μm in diameter, produced at the tips of fusoid hyphae, usually seperating readily but sometimes adhering in short chains. Sclerotia typically of circular to elliptical outline, often irregular, distinctly cupped, smooth on the concave surface; (1.5 -6) mm × (2-8) mm × (0.5-1.5) mm; at maturity black throughout. Its rDNA ITS gene sequence was most similar to sequences of Ovulinia azaleae deposited in GenBank with more than 99% identity. The morphological characteristics and phylogenetic analysis confirmed the fungal strain as O. azaleae. The pathogenicity test showed that the strain OV5 infect azalea by forming typical symptoms of azalea petal blight. This is the first interception report of O. azaleae from the Japan in China.