• Mycobiology
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• v.46 no.2
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• pp.85-91
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• 2018

Endophytic fungi strains (n = 81) were isolated from the leaves, barks, and fruits of Camellia oleifera from Hunan province (China) to delineate their species composition and potential as biological control agents of C. oleifera anthracnose. The fungi were identified by morphological and phylogenetic analyses. Fungal colonization rates of the leaves, barks, and fruits were 58.02, 27.16, and 14.81%, respectively. The isolates were identified as 14 genera, belonging to two subdivisions, Deuteromycotina and Ascomycotina; 87.65% of all isolates belonged to Deuteromycotina. The dominant species, occurring with a high relative frequency, were Pestalotiopsis sp. (14.81%), Penicillium sp. (14.81%), and Fusarium sp. (12.35%). The Simpson's and Shannon's diversity indices revealed the highest species diversity in the leaves, followed by the barks and fruits. The similarity index for the leaves versus barks comparison was the highest, indicating that the number of endophytic fungal species shared by the leaves and barks was higher than barks and fruits or leaves and fruits. Based on the results of dual culture experiments, only five strains exhibited antifungal activity against C. oleifera anthracnose pathogen, with isolate ty-64 (Oidium sp.) generating the broadest inhibition zones. Our results indicate that the endophytes associated with C. oleifera could be employed as natural agents controlling C. oleifera anthracnose.

• The Plant Pathology Journal
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• v.28 no.2
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• pp.149-155
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• 2012

A field trial was conducted in 2009/2010 and 2010/2011 growing seasons at Giza Agricultural Research Station to examine correlations between some biochemical componets and powdery mildews ($PM_s$) resistance in flax cultivars. Nine flax cultivars could be divided into five distinct groups, i.e., highly susceptible (Cortland and C.I. 2008), moderately susceptible (Giza 7, and Marshall), moderately resistant (Cass), resistant (Koto, Dakota and Wilden), and highly resistant (Ottowa 770B). The cultivars showed considerable variation in PM severity ranged from 8.05 on Ottowa 770B to 97.02% on Cortland. Total soluble proteins, total phenols, antioxidant enzymes (peroxidase and polyphenoloxidase), ascorbic acid, tocopherol, and malondialdehyde (MDA), were determined in uninfected leaves of the tested cultivars. Pearson's correlation coefficient was calculated to measure the degree of association between PM severity and each component. All components showed significant (P < 0.05) or highly significant (P < 0.01) negative correlation with PM severity except MDA, which showed positive correlation (P < 0.01). Linear regression analysis was used to evaluate the causal relationship between the biochemical components (independent variables) and PM severity (dependent variable). Coefficient of determination ($R^2$) values of the generated models ranged from 48.76 to 77.15%. Tocopherol, MDA, and proteins were the most important contributors to the total variation in PM severity as the $R^2$ values of their models were 71.78, 75.28, and 77.15%, respectively. The results of the present study suggest that tocopherol, MDA, and proteins in uninfected leaves can be used as biochemical markers to predict PM resistance in flax.

• The Plant Pathology Journal
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• v.25 no.1
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• pp.86-90
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• 2009

In November 2008, typical powdery mildew symptoms were observed on leaves of Arabidopsis thaliana ecotype Col-0 plants in a growth room under controlled laboratory conditions at Korea University, Seoul. The disease was characterized by the appearance of white powder-like fungal growth on the surface of infected leaves. As the disease progressed, infected leaves exhibited chlorotic or necrotic brown lesions, and leaf distortion and senescence. Conidiophores of the causal fungus were hyaline, unbranched, 3-4 celled, cylindrical, and $80-115{\times}6-9{\mu}m$ in size. Singly produced conidia (pseudoidium type) were hyaline, oblong to cylindrical or oval in shape, and $26-55{\times}15-20{\mu}m$ in size with a length/width ratio of average 3, angular/rectangular wrinkling of outer wall and no distinct fibrosin bodies. Appressoria on the hyphae were multi-lobed. These structures are typical of the powdery mildew Oidium subgenus Pseudoidium, anamorph of the genus Erysiphe. The measurements of the fungal structures coincided with those of Erysiphe cruciferarum. The phylogenetic analysis using ITS rDNA sequences revealed that the causal fungus Erysiphe sp. KUS-F23994 is identical to E. cruciferarum. The isolated fungus incited powdery mildew symptoms on the inoculated Arabidopsis leaves, which proved Koch's postulates. Taken all data together, we first report the occurrence of powdery mildew disease of A. thaliana caused by Erysiphe cruciferarum in Korea.