scholarly journals First Report of Corn Kernel Brown Spot Disease Caused by Mucor irregularis in China

Plant Disease ◽  
2015 ◽  
Vol 99 (1) ◽  
pp. 159-159
Author(s):  
X. D. Peng ◽  
S. L. Huang ◽  
S. H. Lin
Keyword(s):  
Morphological Characteristics ◽  
Brown Spot ◽  
Corn Kernel ◽  
Spot Disease ◽  
Rdna Its ◽  
Light Yellow ◽  
Brown Spot Disease ◽  
Mucor Irregularis ◽  
Rdna Its Sequences ◽  
Pathogenicity Tests

In October 2012, a brown spot disease was found on corn kernels during a field survey in Nanyang city (33°01′ N, 112°29′ E), China. The incidences of affected ears and kernels were 2 to 10% (n = 600) and 0.08 to 0.4% (n = 25,000), respectively. Symptoms first appeared as circular or irregular brown spots on the endosperm. These spots subsequently enlarged or coalesced, resulting in the formation of a large light-brown or light-yellow irregular speckle commonly surrounded by a dark-brown edge. Pure fungal cultures with similar morphological characteristics were obtained from surface-disinfected symptomatic kernels using a conventional method for isolation of culturable microbes. The isolated fungal cultures were purified by single-spore isolation (3). A representative isolate F1 was randomly selected, used for pathogenicity tests, and identified using morphological and molecular methods. Colonies on PDA were circular with abundant villiform aerial mycelia. The color of colonies was white-gray at first and turned to light yellow or became ochraceous after 3 days of incubation at 28°C. Hyphae were hyaline and less septate, with rectangular branches. Sporangiophores were erect and unbranched or branched, with globose sporangia formed on their tips. Sporangiospores were elliptical to round, 3.6 to 7.3 × 1.6 to 3.7 μm (n = 100) in size. Two gene regions were amplified for multilocus sequence typing. The D1/D2 region of the nuclear large subunit ribosomal RNA gene (nucLSU) was amplified with primers NL1 and NL4 and the rDNA internal transcribed spacer (ITS) with primers ITS1 and ITS4. PCR products were purified using an Axygen nucleic acid purification kit for sequencing. Both rDNA D1/D2 and rDNA-ITS sequences were submitted to GenBank with accession numbers KM093834 and KM203872, respectively. The isolate F1 showed 98% identity with two isolates of Mucor irregularis (KC524427 and KC461926) in rDNA-ITS sequences and 99% identity with multiple isolates (JX976221, JX976203, and JX976219) of M. irregularis in rDNA D1/D2 sequences. Pathogenicity tests of isolate F1 were conducted based on Koch's postulates. Thirty kernels of fresh ears (milk stage) were pricked by sterilized toothpicks and separately inoculated with a sporangiospore suspension (1 × 106 spores/ml) and 5-day-old mycelial plugs (5 × 5 mm) of isolate F1. Kernels on ears that were inoculated with sterilized water and pure PDA plugs were separately used as controls. After 7 days of incubation, brown spot symptoms developed on the F1-inoculated kernels, which were similar to those observed on the naturally infected ears from the field samples. The control ears remained symptomless during the inoculation tests. Fungal cultures showing the same morphological characteristics as those of isolate F1 were consistently recovered from the diseased cobs inoculated by isolate F1, indicating that M. irregularis was responsible for corn kernel brown spot disease. M. irregularis was reported as a pathogen causing human skin diseases in China (5), America (1), and India (2) and as a phytopathogen causing fruit rot on durian (4). This is the first report of M. irregularis causing corn kernel brown spot disease in China. References: (1) M. M. Abuali et al. J. Clin. Microbiol. 47:4176, 2009. (2) B. M. Hemashettar et al. J. Clin. Microbiol. 49:2372, 2011. (3) S. L. Huang and K. Kohmoto. Bull. Fac. Agric., Tottori Univ. 44:1, 1991. (4) W. F. Wang et al. Plant Quarant. l23:60, 2009. (5) Y. Zhao et al. Mycopathologia 168:243, 2009.

scholarly journals First Report of Alternaria tenuissima Causing Brown Spot Disease of Angelica dahurica in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Shipeng Han ◽  
Qing Wang ◽  
Shuo Zhang ◽  
Xi Jin ◽  
Zhi Min Hao ◽  
...  
Keyword(s):  
Morphological Characteristics ◽  
Brown Spot ◽  
Angelica Dahurica ◽  
Sterile Water ◽  
Single Spore ◽  
Transparent Plastic ◽  
Alternaria Tenuissima ◽  
First Report ◽  
Spot Disease ◽  
Brown Spot Disease

Angelica dahurica (Fisch. ex Hoffm.) is an abundantly cultivated Chinese herbal medicine plant in China with about 4000 hectares grown, the annual production is up to 24,000 tons. The medicinal part of A. dahurica is its root, and mainly function for treat cold, headache, toothache, rhinitis, diabetes, etc. Besides, A. dahurica is also used as a spice in Asia. In September 2018, brown spot was observed on the leaves of A. dahurica in fields of Anguo City, Hebei Province, China. In the field investigated, the incidence of brown spot disease reached 15%. The infected leaves showed brown spots surrounded with pale yellow edge, resulting in withered of the whole leaf. It seriously endangers the growth of A. dahurica, reducing the yield and quality of medicinal materials, even leading to the death of plants. We isolated the pathogen from 10 leaves with same lesions, the small square leaf pieces of approximately 3 to 5 mm were obtained with the sterile scissors from the junction of infected and healthy tissues, sterilized with sodium hypochlorite (10%) for 1 min followed by washing in sterile water for 3 times, then incubated on potato dextrose agar (PDA) plates at 25°C for 4 days. The culture was transferred to new PDA plates and was cultivated in dark at 25°C for 10 days. A total of 3 species of fungi were isolated, and only one fungus species has been found to be able to cause the original pathological characteristics of A. dahurica leaves through the back-grafting experiment. The mycelium was black and began to sporulate after 8 days on PDA media by single spore separation. Multiple spores joined together to form spores chain. The spores were spindle-shaped, yellow to yellow brown, and size ranged from 45 to 55 × 15 to 20 µm (n=50), with zero to three longitudinal septa and one to five transverse septa. For pathogenicity tests, the spore suspension (3.5×105 spores/mL) were inoculated to healthy plants grown in experimental field, the test was repeated four times, and 10 leaves were inoculated in each repetition, and the sterile water was inoculated as the blank control. Inoculated leaves were covered with transparent plastic bags for 24 h to keep humidity. Nine days later, it was found that there were lesions on the leaves inoculated with the pathogen, and the traits were the same as those in the field, while the controls are healthy. The fungus was consistently isolated from the inoculated leaves. The similar isolates were re-isolated from the inoculated and infected leaves and identified as Alternaria tenuissima by DNA sequencing, fulfilling Koch’s postulates. Fungal genomic DNA was extracted from 7-day-old culture. PCR amplifications were performed using primers ITS1 / ITS4 and TEFF / TEFR respectively (Takahashi et al. 2006, Du 2008). The nucleotide sequence of PCR products, which have been deposited in Genebank under the accession numbers MN153514 and MN735428, showed 99.8%-100% identity with the corresponding sequences of A. tenuissima (MW194297 and MK415954). In order to further identify the pathogen species, we constructed a phylogenetic tree by combining TEF sequence and ITS sequence to distinguish the relationship between the pathogen and other minor species in the genus Alternaria, the isolate was clustered in the Alternaria clade. Therefore, the pathogen was identified as A. tenuissima based on the morphological characteristics and molecular identification. To our knowledge, this is the first report of A. tenuissima causing leaf spot on A. dahurica in China.

scholarly journals Alginate encapsulation of Trichoderma harzianum against brown spot disease on rice (Oryzae sativa) in vivo assays

Food Research ◽  
2020 ◽  
Vol 4 (S5) ◽  
pp. 138-141
Author(s):  
I.S. Mohd Anuar ◽  
K.A. Ku Sulong ◽  
H. Abdul Ghani ◽  
M.Z. Wahab
Keyword(s):  
Morphological Characteristics ◽  
Rice Seedling ◽  
Brown Spot ◽  
Conidial Suspension ◽  
Bipolaris Oryzae ◽  
Spot Disease ◽  
Alginate Encapsulation ◽  
Brown Spot Disease ◽  
Rice Plantation

Bipolaris oryzae causes brown spot disease which is one of the most devastating diseases in rice. Nowadays, biological methods are effective controls which need to be developed in order to use less chemical control. Therefore, the objectives of the present study were to characterize the B. oryzae as a biocontrol agent and to measure the performance of encapsulated T. harzianum in controlling brown spot disease. Bipolaris oryzae was characterized based on morphological characteristics and alginate encapsulation was produced from conidial suspension by adding sodium alginate and calcium chloride which results in small beads. Alginate formulation was applied to the rice seedling to find the result on this formulation. As a result, the application of encapsulation T. harzianum to control brown spot disease showed the inhibition of the disease. As a conclusion, this can be an alternative method to control brown spot disease which will render easier application to rice plantation in the future.

scholarly journals Studies on host-selective toxins produced by a pathotype of Alternaria citri causing brown spot disease of mandarins.

1986 ◽  
Vol 50 (6) ◽  
pp. 1597-1606 ◽  
Author(s):  
Yoshiki KONO ◽  
J. M. GARDNER ◽  
Yoshikatsu SUZUKI ◽  
Setsuo TAKEUCHI
Keyword(s):  
Brown Spot ◽  
Spot Disease ◽  
Brown Spot Disease

Brown spot disease in ‘Rocha’ pear Portuguese orchards

2021 ◽  
pp. 335-342
Author(s):  
P. Reis ◽  
C. Rego ◽  
M. Mota ◽  
T. Comporta ◽  
C.M. Oliveira
Keyword(s):  
Brown Spot ◽  
Spot Disease ◽  
Brown Spot Disease

scholarly journals Brown spot disease severity, yield and yield loss relationships in pigmented upland rice cultivars from East Nusa Tenggara, Indonesia

2020 ◽  
Vol 21 (4) ◽  
Author(s):  
Yosep S. Mau ◽  
Antonius Ndiwa ◽  
Shirly Oematan
Keyword(s):  
Disease Severity ◽  
Yield Loss ◽  
Upland Rice ◽  
Brown Spot ◽  
Yield Reduction ◽  
Rice Cultivars ◽  
Rice Varieties ◽  
Resistance Level ◽  
Spot Disease ◽  
Brown Spot Disease

Abstract. Mau YS, Ndiwa ASS, Oematan SS. 2020. Brown spot disease severity, yield and yield loss relationships in pigmented upland rice cultivars from East Nusa Tenggara, Indonesia. Biodiversitas 21: 1625-1634. Brown spot is one of the most devastating diseases of rice, which could lead to total yield loss. The disease has a worldwide distribution, more specifically in areas where water supply is scarce, most specifically in the dry upland areas. Almost all stages of rice are affected by the disease, where leaves and grains are mostly affected. Considerable differences exist in susceptibility to brown spot among rice varieties, which may cause a large variation in yield loss caused by the disease. Therefore, the resistance level of rice varieties and their yield reduction has to be regularly evaluated and updated. There are only a few reports on the relationship between brown spot severity with yield and yield loss of upland rice, and is even lacking in pigmented upland rice. The objectives of the present study were to assess the brown spot severity and resistance level in pigmented upland rice cultivars from East Nusa Tenggara Province, Indonesia, and to elucidate their relationships with yield and yield reduction. Twenty four pigmented upland rice genotypes were evaluated in the field during May to October 2019, and their disease responses and yields were recorded. Disease severity was observed weekly and used to calculate Area Under the Disease Progress Curve (AUDPC) for comparison among the genotypes. The relationships between disease severity and AUDPC with yield and yield loss were also examined. The results showed significant variation in brown spot severity and AUDPC, ranging from, respectively, 11.11% to 40.70% and 398.42%-days to 1081.30%-days. Yields and yield losses of test genotypes also varied substantially. Yields under diseased-free and diseased plots ranged from, respectively, 2.34 t ha-1 to 6.13 t ha-1 and 1.68 t ha-1 to 3.74 t ha-1 while yield loss was between 10.46% and 56.15%. Six genotypes were moderately resistant, four genotypes were moderately susceptible and 14 genotypes were susceptible to brown spot. Neither disease severity nor AUDPC had a linear relationship with yield but both exhibited positive and linear relationships with yield loss.

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