Study On The Identification And Biological Chara-Cteristics Of Pathogenic Fungi Of Peony Leaf Spot

With the expansion of cultivated area and plant life of Peony in China and the increase in frequency of foreign exchange, new diseases continue to rise and the damage of old diseases, especially fungal diseases, has been a key facter in restricting the industrial development of Peony in China. Currently, the studies on systematic investigation of peony diseases and pathogen identification is very little in our country. In order to investigate the peony leaf fungal diseases, this study selected the country Peony Garden, Luoyang City of Garden, Baiyun Mountain Alpine Peony Garden and other major peony plantations, nurseries to identify pathogens according to symptoms and morphology, combined with molecular biology characteristics.Ten kinds of fungal diseases were found and black spot, leaf mold and red spot are the most serious diseases. Seven kinds of pathogens included black spot had been identified on morphology, and they were Alternaria su?ruticosae, A. su?ruticosicola, A. tenuissima, Cercospora paeoniae, Cladosporium paeoniae Pass, Botrytis paeoniae Oudem, Erysiphe paeoniae, Pestalotiopsis paeoniae and Phyllosticta commons. However, Peony red spot (strain 1), Peony tumor spot (strain 2) and Peony leaf spot (strain 3) were difficult to determine by their morphological character alone, so further study is needed at the molecular level.PCR amplification products of ITS of rDNA of the three strains obtained were sequenced. Compared strain1 and strain 2 with the ITS sequnces of Pilidium concavum numbered AY487094.1 of GENBANK, the homologies were 100% and 99.58% seperately. The results showed that both strain 1 and strain 2 were Pilidium concavum, while strain 3 is Discosia sp..Studies on the biological characteristics of Pilidium concavum showed that the optimum grown was PDA, the optimum sporulation was PYA. The optimum grown temperature was 25℃, the optimum temperature for sporulation was 30℃. The optimum growth pH was 6, sporulation was a maximum of pH 11. Light had no significant effect on mycelial growth and sporulation. Glucose and yeast were the most suitable carbon and nitrogen sources for mycelial growth. Conidia germinated during RH 65%-100% and the germination rate increased with the increase of RH. when RH is saturated, spore reached its maximum germination rate 94.51%. The lethiferous temperature of conidia was 51℃for l0 min.In this study, based on morphology, pathogenic fungi of Peony leaf spot were further identified at the molecular level. The results indicate that Pilidium concavum and Discosia sp. are new pathogens on Peony in our country. Biological characteristics of P. concavum had a great significance on further revealing the prevention and treatment of fungal diseases of peony.