scholarly journals Production, Survival, and Evaluation of Solid-Substrate Inocula of Penicillium oxalicum, a Biocontrol Agent Against Fusarium Wilt of Tomato

2002 ◽  
Vol 92 (8) ◽  
pp. 863-869 ◽  
Author(s):  
I. Larena ◽  
P. Melgarejo ◽  
A. De Cal
Keyword(s):  
Fusarium Wilt ◽  
Biocontrol Agent ◽  
Solid Substrate ◽  
Penicillium Oxalicum ◽  
Conidial Suspension ◽  
Conidial Production ◽  
Plastic Bags ◽  
General Decline ◽  
Leguminous Seeds ◽  
Solid Fermentation

Production of conidia of Penicillium oxalicum (ATCC number pending), a biocontrol agent of Fusarium oxysporum f. sp. lycopersici, was tested in liquid and solid fermentation. P. oxalicum produced 250-fold more conidia in solid than in liquid fermentation at 30 days after inoculation of substrate. Solid fermentation was carried out in plastic bags (600 cm3) especially designed for solid fermentation (VALMIC) containing 50 g of peat/vermiculite (PV) (1:1, wt/wt) with 40% moisture, sealed, sterilized, and then inoculated with 1 ml of a conidial suspension of P. oxalicum (105 conidia g-1 dry substrate), sealed again, and incubated in darkness at 20 to 25°C for 30 days. Addition of amendments to PV in a proportion of 0.5 (wt/wt) significantly increased conidial production of P. oxalicum. The best production was obtained on PV plus meal of cereal grains (barley) or leguminous seeds (lentil) (100-fold higher). Conidial production obtained after 5 days of inoculation was similar to that obtained at 30 days. However, viability of conidia produced in PV plus lentil meal was 35% higher than that of conidia produced in PV plus barley meal. Changes in proportions (1:1:0.5, wt/wt/wt; 1:1:1, wt/wt/wt; 1:0.5:0.5, wt/wt/wt; 1:1:0.5, vol/vol/vol) of components of the substrate (peat/vermiculite/lentil meal) did not enhance production or viability of conidia. Optimal initial moisture in the substrate was 30 to 40%. At lower moistures, significant reductions of production of conidia were observed, particularly at 10%. There was a general decline in the number of conidia in bags with time of storage at -80, -20, 4, and 25°C, or at room temperature (range from 30 to 15°C), with the highest decline occurring from 60 to 180 days. Conidial viability also was reduced with time, except for conidia stored at -20°C. Fresh conidia produced in solid fermentation system or those conidia stored at -20°C for 180 days reduced Fusarium wilt of tomato by 49 and 61%, respectively.

scholarly journals Veronica sibirica Leaf Spots Caused by Phacellium veronicae, a New Disease in China

Plant Disease ◽  
2013 ◽  
Vol 97 (12) ◽  
pp. 1662-1662 ◽  
Author(s):  
Q. R. Bai ◽  
S. Han ◽  
Y. Y. Xie ◽  
J. Gao ◽  
Y. Li
Keyword(s):  
Morphological Characteristics ◽  
Its Region ◽  
Control Treatment ◽  
Perennial Herb ◽  
Conidial Suspension ◽  
New Disease ◽  
Medical College ◽  
Leaf Spots ◽  
Plastic Bags ◽  
Insect Bites

Veronica sibirica (Veronicastrum sibiricum) is an erect perennial herb, an ornamental, and a traditional Chinese medicine plant distributed mostly in northeastern, northern, and northwestern China. It has dehumidifying and detoxifying properties, and is mainly used for the treatment of cold, sore throat, mumps, rheumatism, and insect bites (4). In June 2008 through 2012, leaf spots of V. sibirica were observed in the Medicinal Herb Garden of Jilin Agricultural University (43°48′N, 125°23′E) and the medicinal plantations of Antu County (43°6′N, 128°53′E), Jilin Province. Leaf spots were amphigenous, subcircular, angular-irregular, brown, and 1 to 10 mm in diameter; they occasionally merged into a larger spot with an indefinite margin or with a pale center and dark border. Pale conidiomata were hypophyllous and scattered on the spots. The conidiophores were 100 to 400 μm high and clustered together to form synnemata 20 to 50 μm in diameter, which splayed out apically and formed loose to dense capitula. Conidiophores occasionally emerged through the stomata individually and produced conidia on the surface of the infected leaves. The conidiogenous cell terminal was geniculate-sinuous with somewhat thickened and darkened conidial scars. Conidia were solitary or catenulate, ellipsoid-ovoid or subcylindric-fusiform, hyaline and spinulose, 4.01 to 7.18 × 11.16 to 20.62 μm with obtuse to somewhat attenuated ends, and slightly thickened, darkened hila. Six isolates were obtained from necrotic tissue of leaf spots and cultured on potato dextrose agar at 25°C. After incubation for 14 days, colony surfaces were white to pinkish. The colony diameter increased by 12 mm after 21 days' incubation. Hyphae were hyaline, septate, and branched. Conidiophores grew individually or fascicularly. The symptoms and morphological characteristics were consistent with previous descriptions (1,2), and the fungus was identified as Phacellium veronicae (Pass.) (U. Braun 1990). The internal transcribed spacer (ITS) region of the nuclear rDNA was amplified using primers ITS4/ITS5 (3). The ITS was identical among all six isolates (HE995799) and 98% identical to that of P. veronicae (JQ920427, HQ690097). Pathogenicity was confirmed by spraying five 1-year-old V. sibirica seedlings with a conidial suspension (106 conidia/ml) of each isolate and five seedlings with sterile water as a control treatment. Plants were grown in the greenhouse at 20 to 25°C and were covered with plastic bags to maintain humidity on the foliage for 72 h. After 15 days, the same symptoms appeared on the leaves as described earlier for the field-grown plants; the control plants remained healthy. The same fungus was reisolated from the leaf spots of inoculated plants. Currently, the economic importance of this disease is limited, but it may become a more significant problem, as the cultivated area of V. sibirica is increasing. To our knowledge, although P. veronicae was recorded on the other species of Veronica (V. austriaca, V. chamaedrys, V. grandis, V. longifolia, V. paniculata, and V. spicata ssp. incana) in Europe (Germany, Denmark, Ireland, Romania) and V. wormskjoldii in North America (Canada) (1), this is the first report of V. sibirica leaf spots caused by P. veronicae in the world, and it is a new disease in China. References: (1) U. Braun. A monograph of Cercosporella, Ramularia and allied genera (phytopathogenic Hyphomycetes) 2, IHW-Verlag, Germany, 1998. (2) U. Braun. Nova Hedwigia 50:499, 1990. (3) D. E. L. Cooke et al. Mycol. Res. 101:667, 1997. (4) Jiangsu New Medical College. Dictionary of Chinese Materia Medica. Shanghai: Shanghai Scientific and Technical Publishers, China, 1977.

scholarly journals First Report of the Pathogenicity of Colletotrichum gloeosporioides on Invasive Ferns, Lygodium microphyllum and L. japonicum, in Florida

Plant Disease ◽  
2003 ◽  
Vol 87 (1) ◽  
pp. 101-101 ◽  
Author(s):  
K. A. Jones ◽  
M. B. Rayamajhi ◽  
P. D. Pratt ◽  
T. K. Van
Keyword(s):  
Colletotrichum Gloeosporioides ◽  
First Record ◽  
South Florida ◽  
Growth Chamber ◽  
Fluorescent Light ◽  
Distilled Water ◽  
Conidial Suspension ◽  
Potted Plants ◽  
Plastic Bags ◽  
Fern Species

Lygodium microphyllum (Cav.) R.Br. (Old World climbing fern) and L. japonicum (Thunb.) Sw. (Japanese climbing fern), in the family Schizaeaceae, are among the most invasive weeds in Florida (1). L. microphyllum invades fresh water and moist habitats in south Florida, while L. japonicum has spread in relatively well-drained habitats from Texas to North Carolina and central Florida. Some potted plants of both Lygodium spp. grown in shadehouse as well as in full sunlight developed discolored spots on pinnules (foliage), which coalesced and resulted in browning and dieback of severely infected vines. Symptomatic foliage obtained from these plants was surface-sterilized by immersing in a 15% solution of commercial bleach for 90 s, followed by a series of four rinses with sterile deionized distilled water. Disks (4 mm in diameter) of pinnules were cut from the junction of discolored and healthy tissues and placed on potato dextrose agar (PDA). A fungus, Colletotrichum gloeosporioides (Penz.) Penz. & Sacc. was consistently isolated from these disks. Fungal colonies produced abundant conidia on PDA. Conidia were hyaline, straight, cylindrical, averaging 14.7 μm (range 12.5 to 17.5 μm) × 5.0 μm (range 3.8 to 7.5 μm), and similar to those described for C. gloeosporioides (2). To confirm the pathogenicity of C. gloeosporioides on L. microphyllum and L. japonicum, Koch's postulates were performed. A fungal isolate was grown on PDA for 3 weeks, after which 10 ml of sterile deionized distilled water was added to the culture and agitated to dislodge conidia. The conidial suspension was strained through three layers of cheesecloth to remove hyphal fragments, and its concentration was adjusted to 1.7 × 106 conidia/ml. Foliage of healthy L. microphyllum and L. japonicum plants grown in 500-ml containers was sprayed with the conidial suspension until runoff. Plants were covered with plastic bags whose inner sides were misted with water to maintain high humidity and placed in a growth chamber under 12 h of fluorescent light per day. Temperature and relative humidity in the chamber ranged from 26 to 29°C and 44 to 73%, respectively. Plastic bags were removed after 3 days, and plants were further incubated for 3 weeks in the same growth chamber. Control plants were sprayed with sterile water, covered with plastic bags, and exposed to the same temperature, light, and humidity regime as those of the fungus-inoculated plants. Small, discolored foliar spots appeared 3 days after fungus inoculation. These spots were similar to those observed on pinnules of potted plants that originated from shadehouse and outdoor environments. Within 3 weeks after inoculation, the foliage of L. japonicum developed abundant discolored spots that led to edge browning and wilting of the pinnules. L. microphyllum had similar but more severe symptoms, with plants suffering as much as 50% dieback. C. gloeosporioides was consistently reisolated from the symptomatic tissues of both fern species. No symptoms appeared on the water-inoculated plants. To our knowledge, this is the first record of C. gloeosporioides pathogenicity on L. microphyllum and L. japonicum. References: (1) R. W. Pemberton and A. P. Ferriter. Am. Fern J. 88:165, 1998. (2) B. C. Sutton. Colletotrichum: Biology, Pathology and Control. CAB International, Wallingford, Oxon, UK, 1992.

Characterization and sequence analysis of potential biofertilizer and biocontrol agent Bacillus subtilis strain SEM-9 from silkworm excrement

2019 ◽  
Vol 65 (1) ◽  
pp. 45-58 ◽  
Author(s):  
Qingrong Li ◽  
Sentai Liao ◽  
Huyu Zhi ◽  
Dongxu Xing ◽  
Yang Xiao ◽  
...  
Keyword(s):  
Bacillus Subtilis ◽  
Fusarium Wilt ◽  
Biocontrol Agent ◽  
Gene Clusters ◽  
Antagonistic Effect ◽  
Subtilis Strain ◽  
Fusarium Spp ◽  
Antagonistic Microorganisms ◽  
Biochemical Analyses ◽  
Physiological And Biochemical

Fusarium wilt is a devastating soil-borne disease caused mainly by highly host-specific formae speciales of Fusarium oxysporum. Antagonistic microorganisms play a very important role in Fusarium wilt control, and the isolation of potential biocontrol strains is becoming more and more important. We isolated a bacterial strain (SEM-9) from the high-temperature stage of silkworm excrement composting, which had a marked ability to solubilize phosphorus, promote the growth and increase the yield of the small Chinese cabbage, and which also exhibited considerable antagonistic effect towards Fusarium sambucinum and other fungi. The result of physiological and biochemical analyses, as well as genome sequencing, showed that SEM-9 was a strain of Bacillus subtilis. Through genome annotation and analysis, it was found that SEM-9 contained genes related to the regulation of biofilm formation, which may play an important role in colonization, and gene clusters encoding the biosynthesis of antimicrobials, such as surfactin, bacilysin, fengycin, and subtilosin-A. The production of such antifungal compounds may constitute the basis of the mode-of-action of SEM-9 against Fusarium spp. These data suggested that the SEM-9 strain has potential as both a biofertilizer and a biocontrol agent, with the potential to manage Fusarium wilt disease in crops.

scholarly journals Newly Isolated Streptomyces sp. JBS5-6 as a Potential Biocontrol Agent to Control Banana Fusarium Wilt: Genome Sequencing and Secondary Metabolite Cluster Profiles

2020 ◽  
Vol 11 ◽  
Author(s):  
Tao Jing ◽  
Dengbo Zhou ◽  
Miaoyi Zhang ◽  
Tianyan Yun ◽  
Dengfeng Qi ◽  
...  
Keyword(s):  
Fusarium Wilt ◽  
Complete Genome ◽  
Biocontrol Agent ◽  
Fermentation Broth ◽  
Membrane Integrity ◽  
Gene Clusters ◽  
Wilt Disease ◽  
Gas Chromatography Mass Spectrometry ◽  
Fusarium Wilt Disease ◽  
Potential Biocontrol Agent

Banana is a key staple food and fruit in countries all over the world. However, the development of the global banana industry is seriously threatened by Fusarium wilt disease, which is caused by Fusarium oxysporum f. sp. cubense (Foc). In particular, Foc tropical race 4 (Foc TR4) could infect more than 80% of global banana and plantain crops. Until now, there were no commercial chemicals or resistant cultivars available to control the disease. Biological control using actinomycetes is considered a promising strategy. In this study, 88 actinomycetes were isolated from a banana orchard without symptoms of Fusarium wilt disease for more than 10 years. An actinobacterial strain labeled as JBS5-6 has exhibited strong antifungal activities against Foc TR4 and other selected 10 phytopathogenic fungi. Based on phenotypic and biochemical traits as well as complete genome analysis, strain JBS5-6 was assigned to Streptomyces violaceusniger. Extracts of the strain inhibited the mycelial growth and spore germination of Foc TR4 by destroying membrane integrity and the ultrastructure of cells. The complete genome of strain JBS5-6 was sequenced and revealed a number of key function gene clusters that contribute to the biosynthesis of active secondary metabolites. Sixteen chemical compounds were further identified by gas chromatography-mass spectrometry (GC-MS). 5-hydroxymethyl-2-furancarboxaldehyde was one of the dominant components in strain JBS5-6 extracts. Moreover, fermentation broth of strain JBS5-6 significantly reduced the disease index of banana seedlings by inhibiting the infection of Foc TR4 in a pot experiment. Hence, strain JBS5-6 is a potential biocontrol agent for the management of disease and the exploitation of biofertilizer.

scholarly journals Potential of non-pathogenic Fusarium oxysporum isolates for control of Fusarium wilt of tomato

2005 ◽  
Vol 30 (4) ◽  
pp. 409-412 ◽  
Author(s):  
Juliano C. da Silva ◽  
Wagner Bettiol
Keyword(s):  
Fusarium Oxysporum ◽  
Fusarium Wilt ◽  
Antagonistic Activity ◽  
Healthy Plant ◽  
Conidial Suspension ◽  
Vascular Wilt ◽  
Tomato Seedling ◽  
Seedling Roots ◽  
Race 2 ◽  
Cultivation Substrate

This study was done to evaluate the efficiency of non-pathogenic Fusarium oxysporum isolates (141/3, 233, 233/1, 245, 245/1, 251, 251/2, 251/5, and 257) in controlling vascular wilt caused by F. oxysporum f. sp. lycopersici, race 2 (isolates C-21A, TO11, and TO245) in tomato (Lycopersicon esculentum) cv. Viradoro seedlings. In order to determine the effect of non-pathogenic F. oxysporum isolates in tomato plants, the root system of 30-day-old seedlings was immersed in conidial suspensions (10(6) ml-1) of each isolate and the seedlings were transplanted to a cultivation substrate. Thirty-five days after transplanting it was observed that the non-pathogenic F. oxysporum isolates were not pathogenic to the cv. Viradoro nor did they affect seedling development. The efficiency of the non-pathogenic F. oxysporum isolates in controlling Fusarium wilt was determined by immersing the tomato seedling roots in the conidial suspension (10(6) ml-1) of each isolate and then transplanting them into substrates previously infested with isolates of F. oxysporum f.sp. lycopersici, race 2 (10(5) conidia ml-1 of substrate). Evaluations were performed 35 days after transplanting, for severity in scale with 1=healthy plant to 6=dead plant or plant showing vessel browning and wilted leaves up to the leader shoot and seedling height. The non-pathogenic F. oxysporum isolates were efficient in reducing the severity of the disease and maintaining normal plant development. These results provide evidence of the antagonistic activity of non-pathogenic F. oxysporum isolates in controlling vascular wilt caused by F. oxysporum f. sp. lycopersici race 2 in tomato.

Growth and sporulation of Cercospora cruenta and Cercospora canescens in culture

1978 ◽  
Vol 56 (3) ◽  
pp. 229-233 ◽  
Author(s):  
E. J. A. Ekpo ◽  
O. F. Esuruoso
Keyword(s):  
Vigna Unguiculata ◽  
Mycelial Growth ◽  
Culture Media ◽  
Conidial Suspension ◽  
Optimum Temperature ◽  
Complete Darkness ◽  
Agar Concentration ◽  
Conidial Production ◽  
Conidia Production ◽  
Apparent Variation

Ten culture media were tested for their effect on growth and sporulation of Cercospora cruenta and C. canescens isolated from field-infected cowpea (Vigna unguiculata). There was very little mycelial growth and little or no conidia production on most media. Oxoid agar supplemented with V-8juice supported best growth and conidial production. Flooding V-8 juice agar with a conidial suspension resulted in multiplicity of tiny colonies with resultant increased sporulation. Conidia produced in culture were slightly longer than those produced in lesions on field-infected leaves and the degree of septation varied with the type of culture media. The width of conidia showed no apparent variation regardless of the culture media. More active mycelial growth but less conidial production was observed at agar concentration of 3% than at lower concentrations. Optimum temperature for mycelial growth and conidial production was 24–25 °C. Growth and conidial production were inhibited in complete darkness but stimulated by light.

scholarly journals First Report of Gummosis Disease of Japanese Apricot Caused by Botryosphaeria dothidea in Taiwan

Plant Disease ◽  
2011 ◽  
Vol 95 (1) ◽  
pp. 77-77
Author(s):  
Y. Ko ◽  
C. W. Liu ◽  
S. S. Chen ◽  
K. Y. Chiu ◽  
Y. W. Sun ◽  
...  
Keyword(s):  
Direct Sequencing ◽  
Morphological Characteristics ◽  
Pcr Amplification ◽  
Conidial Suspension ◽  
Botryosphaeria Dothidea ◽  
Cortical Cells ◽  
Japanese Apricot ◽  
First Report ◽  
Representative Sequence ◽  
Plastic Bags

Japanese apricot (Prunus mume Sieb. et Zucc.) is an economically important fruit crop grown on more than 10,000 ha in Taiwan. During May 2008, twigs of Japanese apricot trees in the commercial farms of Renai Region (Nantou County) showed symptoms of gummosis disease, with 12 to 18% of the trees affected. The disease was more severe on trees weakened by drought stress. Limb and twig infections began around lenticles as small, sunken, discolored lesions at the margins of wounds. Following infection, cortical cells collapsed, bark became depressed, and blisters developed, which were often cracked with whitish gummy exudation. Necrotic areas were seen on the cortical tissues. Leaves showed yellowing and drooping. In winter months, numerous black pycnidia or perithecia formed on infected twigs. Single conidial isolates of the pathogen were obtained from diseased twigs on acidified potato dextrose agar (PDA) incubated at 25 ± 1°C for 3 days. On the basis of morphological characteristics, the fungus was identified as Botryosphaeria dothidea (3). Conidia (17 to 22.6 × 4.3 to 6.0 μm) were hyaline, unicellular, and spindle shaped. Asci (78 to 125 × 15 to 17 μm) were hyaline, bitunicate, clavate, and eight spored. Ascospores (18 to 22 × 7.0 to 8.2 μm) were hyaline and spindle shaped or fusoid. The pathogen identity was further confirmed by PCR amplification and sequencing of ribosomal DNA internal transcribed spacer from the fungus with the primers ITS5: 5′-GGAAGTAAAAGTCGTAACAAGG-3′ and ITS4: 5′-TCCTCCGCTTATTGATATGC-3′ (4), and a representative sequence was deposited in NCBI GenBank (Accession No. GU594225). The sequence showed 99 to 100% homology with previously characterized strains of B. dothidea (GenBank Accession Nos. EU441944, DQ177876, and AY786320). Pathogenicity tests were conducted with inoculum prepared by culturing the fungus on PDA under a continuous photoperiod of 128 ± 25 μE·m–2·s–1 at 25°C for 3 days. Shallow cuts (3 × 3 × 3 mm) were made on 12- to 15-month-old healthy twigs with a scalpel and inoculated with either a 5-mm mycelial disc or 0.5 ml of conidial suspension (105 conidia/ml) of the fungus. Two twigs on each of six trees were inoculated. Inoculated areas were covered with moist, sterile cotton and the entire twigs were enclosed in plastic bags. Twigs were inoculated with 5-mm PDA discs or sterile water for controls. The symptoms described above were observed on all inoculated twigs 14 days after inoculation, whereas control twigs remained healthy. Reisolation from the inoculated twigs consistently yielded B. dothidea. In Taiwan, B. dothidea has been reported as the causal agent of gummosis of peach (1) and fruit ring rot of pear (2); however, to our knowledge, this is the first report of B. dothidea causing gummosis on Japanese apricot. References: (1) Y. Ko et al. Plant Pathol. Bull. 1:70, 1992. (2) Y. Ko et al. Plant Prot. Bull. (Taiwan) 35:211, 1993. (3) B. Slippers et al. Mycologia 96:83, 2004. (4) T. J. White et al. In: Amplification and Direct Sequencing of Fungal Ribosomal RNA Genes for Phylogenetics. Academic Press. San Diego, CA, 1990.

scholarly journals IDENTIFICATION OF COWPEA GENOTYPES RESISTANT TO FUSARIUM WILT1

2021 ◽  
Vol 34 (4) ◽  
pp. 957-964
Author(s):  
RISONEIDE DE CÁSSIA ZEFERINO SILVA ◽  
ANTHONY CARLOS DA SILVA ◽  
REZANIO MARTINS CARVALHO ◽  
ANTONIO FÉLIX DA COSTA ◽  
ALESSANDRO NICOLI ◽  
...  
Keyword(s):  
Fusarium Wilt ◽  
Conidial Suspension ◽  
The North ◽  
Randomized Design ◽  
Susceptible Control ◽  
Bean Yield ◽  
Descriptive Scale ◽  
The University ◽  
Moderately Resistant ◽  
Resistant Genotypes

ABSTRACT Fusarium wilt, caused by soil-borne Fusarium oxysporum f. sp. tracheiphilum (Fot), can reduce cowpea bean yield. Considering that genetic control through resistant genotypes is pivotal for Fusarium wilt control, the aim of the present study was to identify cowpea genotypes that are resistant to Fot from the Germplasm Bank of the Pernambuco Agronomic Institute, Embrapa Middle North, and other producing areas in the North and Northeast regions of Brazil. The cultivar BR-17 Gurguéia was used as a susceptible control and MNC01-649F-2-1 was used as a resistant control. Two experiments were carried out in a completely randomized design in the greenhouse of the Department of Agronomy of the University Federal Rural of Pernambuco. Plants with the first pair of expanded leaves were inoculated with a conidial suspension (106 conidia/mL) using the conidia root-immersion methodology. Fusarium wilt severity in plants was assessed 21 d after inoculation, with the aid of a descriptive scale. In the first experiment, we evaluated the resistance of 38 cowpea genotypes, of which 19 (5 moderately resistant and 14 resistant) were selected for the second experiment. In the first experiment, four genotypes (Canapu PE, Miranda IPA 207, Esperança, and BRS Pujante) did not show any symptoms of Fusarium wilt. In the second, 15 genotypes showed high resistance to Fot, including Canapu PE and Miranda IPA 207, which again had no symptoms of Fusarium wilt. In conclusion, this study identified that the genotypes, Canapu PE, Miranda IPA 207, Esperança, and BRS Pujante have greater resistance to Fusarium wilt.

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