Investigation of Multiple Pathogens in Black-Spotted Dendrobium officinale Based on Culture-Independent and Dependent Methods

Black spot disease which significantly reduces the quality of medicine plants is quite common in Dendrobium officinale fields. In this study, GXDF33, a strain of Alternaria, together with the reported pathogen Cladosporium, was isolated from symptomatic leaves. The in vitro pathogenicity tests on seedlings showed GXDF33 can cause black spot disease. Based on quantitative real-time polymerase chain reaction (qPCR) result, it was found that the biomass of both Cladosporium and Alternaria increased as the symptom went severer. According to amplicon sequencing data for the symptomatic samples from Guangxi and Zhejiang Provinces in China, Cladosporium and Alternaria were both common genera in symptomatic plants. To our knowledge, this is the first report unveiling the relationship between black spot disease of D. officinale and Cladosporium as well as Alternaria.

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Characterization of Alternaria alternata Causing Black Spot Disease of Pomegranate in Israel Using a Molecular Marker

Plant Disease ◽

10.1094/pdis-12-11-1041-re ◽

2012 ◽

Vol 96 (10) ◽

pp. 1513-1518 ◽

Cited By ~ 7

Author(s):

Tami Gat ◽

Orna Liarzi ◽

Yulia Skovorodnikova ◽

David Ezra

Keyword(s):

Molecular Marker ◽

Alternaria Alternata ◽

Severe Disease ◽

Outer Part ◽

Black Spot ◽

Spot Disease ◽

Black Spots ◽

Detached Leaves ◽

Pathogenicity Tests ◽

Black Spot Disease

Black spot disease of pomegranate is a relatively new disease in Israel that is caused by Alternaria alternata. The symptoms include black spots on leaves and fruit. Only the outer part of the fruit is damaged; the edible tissue remains unaffected. In this study, we obtained 50 isolates of A. alternata from infected pomegranate plants that were classified based on pathogenicity tests using detached leaves. Using an arbitrarily primed polymerase chain reaction, we identified one primer (primer CAG) that reacted only with DNA of isolates that induced the most severe disease symptoms. Based on the sequence of the amplified fragment, we generated a specific primer (primer C) that recognizes these highly virulent isolates. Therefore, we suggest that primer C can be utilized as a molecular marker for the detection of A. alternata isolates that cause black spot disease of pomegranate.

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Effect of Modified Atmosphere for Control of Black Spot, Caused by Alternaria alternata, on Stored Persimmon Fruits

Phytopathology ◽

10.1094/phyto.1997.87.2.203 ◽

1997 ◽

Vol 87 (2) ◽

pp. 203-208 ◽

Cited By ~ 25

Author(s):

D. Prusky ◽

A. Perez ◽

Y. Zutkhi ◽

R. Ben-Arie

Keyword(s):

Alternaria Alternata ◽

Modified Atmosphere Packaging ◽

Black Spot ◽

Inhibitory Effect ◽

Modified Atmosphere ◽

Inhibitory Effects ◽

Spot Disease ◽

Persimmon Fruit ◽

Black Spot Disease

Modified atmosphere packaging (MAP) of persimmon fruit resulted in the accumulation of acetaldehyde to a level of 80 μg/ml; ethanol to a level of 900 μg/ml; and CO2 up to 30%. When fruits were stored at -1°C for 4 months in such atmospheres, the incidence of black spot disease, caused by Alternaria alternata, was reduced. The effects of each of these gases were examined to determine their individual involvement in the inhibition of Alternaria development during storage. When A. alternata, grown at 20°C on potato dextrose agar or inoculated in persimmon fruit, was exposed for 24 h to different levels of each volatile, acetaldehyde was the most fungistatic but only at concentrations higher than those that accumulated under MAP; CO2 was moderately inhibitory at concentrations from 10 to 60%, whereas ethanol had no effect. Similar inhibitory effects were obtained with acetaldehyde at 620 μg/ml or 30% CO2 when in vitro cultures of A. alternata and infected fruits were exposed for up to 2 weeks at 20°C, but 1,000 μg of ethanol per ml had only a transitory inhibitory effect under these conditions. Based on analysis of the effect of concentration versus time for each gas accumulating in MAP, we suggest that the increasing concentration of CO2 during storage is the principal factor in the inhibition of black spot disease development.

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The Diversity of Root-Associated Endophytic Fungi from Four Epiphytic Orchids in China

Diversity ◽

10.3390/d13050197 ◽

2021 ◽

Vol 13 (5) ◽

pp. 197

Author(s):

Tao Wang ◽

Miao Chi ◽

Ling Guo ◽

Donghuan Liu ◽

Yu Yang ◽

...

Keyword(s):

Endophytic Fungi ◽

Southern China ◽

Culture Method ◽

Amplicon Sequencing ◽

Community Diversity ◽

Mycorrhizal Symbiosis ◽

Epiphytic Orchids ◽

Culture Independent ◽

Almost All

Root-associated endophytic fungi (RAF) are found asymptomatically in almost all plant groups. However, little is known about the compositions and potential functions of RAF communities associated with most Orchidaceae species. In this study, the diversity of RAF was examined in four wild epiphytic orchids, Acampe rigida, Doritis pulcherrima, Renanthera coccinea, and Robiquetia succisa, that occur in southern China. A culture-independent method involving Illumina amplicon sequencing, and an in vitro culture method, were used to identify culturable fungi. The RAF community diversity differed among the orchid roots, and some fungal taxa were clearly concentrated in a certain orchid species, with more OTUs being detected. By investigating mycorrhizal associations, the results showed that 28 (about 0.8%) of the 3527 operational taxonomic units (OTUs) could be assigned as OMF, while the OTUs of non-mycorrhizal fungal were about 99.2%. Among the OMFs, Ceratobasidiaceae OTUs were the most abundant with different richness, followed by Thelephoraceae. In addition, five Ceratobasidium sp. strains were isolated from D. pulcherrima, R. succisa, and R. coccinea roots with high separation rates. These culturable Ceratobasidium strains will provide materials for host orchid conservation and for studying the mechanisms underlying mycorrhizal symbiosis.

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