| We studied the pathogen of the suffering protonemal of Porphyra yezoensis Ueda which were collected on July, 2003. The results are as folio wings: the main pathogen was named as GF014. The identification was done by morphological observation, growth characteristics and 18S rDN A sequence and ITS rDNA sequence.7 bacteria, 26 fungi and 10 actinomyces were isolated and pured on Zobell 2216E, M2 +media under 28 ℃.The purified strains were fermented and centrifugated .Put the truffle onto the shells and culture under salinity 1.020, 20℃, 1500-20001ux, 0.001%P-H2PO4, 0.0003%N-NO3 and L: D=12: 12.One strain named GF014 was identified as pathogen by Koch's postulates.The strain GF014 can utilize oganic carbon source and inorganic nitrogen source, grows fast when salinity below 20%o and temperature between 10-28℃.The growth rate of strain GF014 on PDA solid media is generic. Its morphology is villiform, which is white during initial stage, caesious inside, dark caesious from the back, no smell and no exudation. Most mycelia grow on the surface and partly inside. Aerial hypha which have septums inside and many embranchments are eugenic, turquoise and 3.0-7.3μm in diameter. Pycnidium which has a round orifice at the top are black brown, global and 40-110μm in diameter. The conidiophores are single cell, cyan, egg-shape or oval and 0.5-1μm×2-2.5μm in size.All these characters tally with Deuteromycotina Coelomycetes Sphaeropsidales Phoma. So the strain GF014 should be vested in Phoma. Meanwhile, more sorting characters indicate that the size of conidiophores of the strain GF014 is different from all the strains known, so as the morphology and size of conidiophores. As it was identified from Porphyra yezoensis, it is named as Phoma porphyrae as a new strain. It has 99.8% comparability with Leptosphaeria sp. by dendrogram of ITS rDNA sequence analysis.The Phoma has many species and many of them can cause botany's disease. There is no report of Phoma isolated from the porphyra. |
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