非洲菊根腐病病原的鉴定与ITS序列分析

Identification and ITS sequence analysis of the pathogens causing root rot of Gerbera jamesonii in Nanjing area

从南京花卉苗圃的非洲菊腐烂病植株的根部分离到46株真菌菌株,将所有菌株回接到健康的植株上,结果发现只有11个疫霉菌菌株可以引起非洲菊典型的根腐病症状。对上述疫霉菌的形态特征、致病性及核糖体DNA-ITS序列进行分析,结果为所有菌株在LBA平板上菌落圆形、呈放射状、菌丝致密、气生菌丝较丰富、菌丝无隔,能形成大量菌丝膨大体,水培后产生大量椭圆形孢子囊,孢子囊无乳突,游动孢子在孢子囊内形成。进一步克隆并分析供试菌株核糖体DNA-ITS区域的序列,结果是分离菌株与GenBank中隐地疫霉的ITS序列的同源性均为99.87%,仅有1个碱基的差异,进一步明确了本研究中从非洲菊腐烂病植株根部分离的病原菌为隐地疫霉(Phytophthora cryptogea)。

Root rot is one of the most serious diseases in Gerbera jamesonii Bolus, though many pathogens were reported to cause this disease, the real pathogen in Nanjing area was not clear. In order to identify the Flameray Gerbera root rot pathogens, forty six isolates of pathogens were isolated from the root rot of G. jamesonii Bolus grown in Nanjing, after re-inoculated to healthy plants, only eleven Phytophthora isolates could infeet and cause root rot in G. jamesonii. The morphological characteristics, pathogenicity and the sequence of ribosomal DNA-ITS were studied. Based on its abundance, radiation, rounded hyphal swellings in chains, nonpapillate, ovoid sporangium, zoospores formed within sporangium, and the sequence of ribosomal DNA-ITS ,the pathogen was identified as Phytophthora cryptogea.