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This study quantified the spatial variation of endophyte infections in wild populations of commercially important Chondrus ocellatus in Korea. We examined the variation of infection across four locations, two tidal heights and life-history stage (gametophyte vs tetrasporophyte). One hundred and fifty fronds were collected from the upper and lower C. ocellatus zones and microscopic examinations were conducted to determine their infection symptoms. Our results showed that the percentage of C. ocellatus populations infected by endophytic algae were very high, ranging from 58 to 99%, in all populations examined. Endophyte infection severity of Hakampo and Manripo populations was significantly greater in the lower Chondrus zones but it was significantly higher in the upper zone of Jungdori population. Tetrasporophytic fronds were more susceptible to infection by endophytic algae than gametophytic fronds. Also, the infection symptoms were more severe in the middle and basal parts of the fronds than in the apical parts. The findings of this study are very informative data for the endophyte abundance in the field population of commercial C. ocellatus. [ABSTRACT FROM AUTHOR]

A brown filamentous endophyte, Mikrosyphar zosterae, occasionally appears as an epiendophyte of seagrass in Europe and North America. In the present study, M. zosterae was first isolated from wart-like spots of the red alga Chondrus ocellatus and identified by morphological features and molecular analysis. The production of wart-like spots M. zosterae on the host C. ocellatus fronds was confirmed using Koch's postulates and in mixed culture of the two species. Neither hypertrophic nor hyperplastic cells of host C. ocellatus were found in the wart-like spots which differed from gall composition in other species. Wart-like spot formation by brown filamentous M. zosterae on the red macroalgal fronds is reported for the first time. In the culture, three morphological types of M. zosterae were observed, which were heterotrichous, pseudoparenchymatous and monostromatic prostrate thalli. Phaeophycean hairs and reproductive organs (both unilocular and plurilocular sporangia) of M. zosterae were also observed in the culture. In conclusion, M. zosterae is a causative agent producing wart-like spots on Chondrus fronds, which is a new record in red seaweeds and was confirmed in the laboratory culture for the first time. [ABSTRACT FROM AUTHOR]

Monthly variations in gametophyte and tetrasporophyte biomass of Chondrus ocellatus Holmes, a commercial carragenophyte alga, were examined at wave-exposed and sheltered shore stations of Jungdori, Wando, Korea from September, 2013 to August, 2014. The frequency of infection of the fronds with a green filamentous endophyte was investigated and the endophyte was identified using tufA analysis. Biomass of C. ocellatus was significantly greater at the exposed shore (331.84 g wet wt. m) than at the sheltered shore (181 g wet wt. m); the average biomass was 259 g wet wt. m. Gametophyte biomass of C. ocellatus accounted for 64.25% of the total biomass (259 g wet wt. m); tetrasporophyte biomass was 93.05 g wet wt. m (35.93%). Biomass was minimal in winter and maximal in summer at both stations and similar patterns were found for gametophyte and tetrasporophyte biomass. Frond lengths and weights of C. ocellatus were slightly greater at the exposed shore than at the sheltered shore. Fronds of C. ocellatus were infected by a green endophytic species, which grew in between the cortical and medullar tissue and was identified as Ulvella ramosa by tufA analysis. We conclude that the optimal harvesting period of the C. ocellatus field population in terms of biomass might be autumn, after the rapid growth period. Additional in-depth research on the endophytes, such as infection mechanism and frequency, should be performed in order to maintain and manage the field populations of C. ocellatus. [ABSTRACT FROM AUTHOR]