Conidia of hypovirulent strains of Cryphonectriaparasitica differ in their potential for biocontrol of chestnut blight

1992 ◽  
Vol 22 (9) ◽  
pp. 1338-1342 ◽  
Author(s):  
K.L. Scibilia ◽  
F.V. Hebard ◽  
L. Shain
Keyword(s):  
Virulent Strain ◽  
Culture Collection ◽  
American Chestnut ◽  
American Type Culture Collection ◽  
Chestnut Blight ◽  
Virulent Strains ◽  
Hypovirulent Strain

Conidia from eight hypovirulent strains of Cryphonectriaparasitica (Murr.) Barr were suspended in water and applied to the bark of American chestnut (Castaneadentata (Marsh.) Borkh.) trees. Cankers were initiated with mycelium of virulent strains isogenic to the applied conidia. Hypovirulent strains differed significantly in the ability of their conidia to putatively convert isogenic virulent strains in cankers, as indicated by the recovery of cultures with hypovirulent morphology from challenged cankers. A tank mix of conidia from two hypovirulent strains in different conversion groups putatively converted significantly more cankers initiated by isogenic virulent strains than did separate applications of conidia from these strains, particularly when the second application was delayed by 2 weeks. Cankers initiated on excised stems with virulent strain Ep 155 (American Type Culture Collection 38755) yielded cultures with hypovirulent morphology after application of conidia from isogenic hypovirulent strain Ep 780 at densities as low as 50 and 700 conidia/cm2 for inoculations sealed or not sealed with latex caulk, respectively.

scholarly journals The Morphology and the Biological Control of Cryphonectria parasitica

2012 ◽  
Vol 69 (1) ◽  
Author(s):  
Carmen Emilia PUIA ◽  
Daniela Andreea GRIGORESCU ◽  
Raluca Vasilica MICLEA
Keyword(s):  
Biological Control ◽  
Virulent Strain ◽  
Morphological Characteristics ◽  
Castanea Sativa ◽  
Cryphonectria Parasitica ◽  
Chestnut Blight ◽  
Dual Culture ◽  
Natural Form ◽  
Hypovirulent Strain ◽  
Endothia Parasitica

Cryphonectria parasitica  (Murr.) Bar [syn. Endothia parasitica (Murr. And.] (anamorf: Endothiella sp .) is the causal agent of chestnut bark disease or chestnut blight, disease which produced great damages throughout the world, for example, in Europe, the European chestnut tree ( Castanea sativa (P.) Mill) was heavily affected. Environmental concerns have focused attention on natural forms of disease control as an effective alternative to chemical pesticides. In the chestnut blight fungus, Cryphonectria parasitica deals with a natural form of biological control in which the virulence of a fungal pathogen is attenuated by an endogenous viral RNA genetic element- the hypovirulent strain. In our researches we picked samples of chestnut bark from different areas in Maramures county. We’ve isolated the fungus on PDA medium and we’ve studied the morphological characteristics of the usual virulent strain and we looked for a possible hypovirulent strain in order to study its capacity for biological control. The fungus develops in the bark and in cambium where forms a yellowish or brownish stroma and produces both conidia and ascospores. The pycnidia stromata break through the lenticels producing conidia and later in the same stroma develop the perithecia which produce ascospores. Both strains of the fungus were found in the research area. The hypovirulent strain had a slower development, showed no sporu lation and pigmentation “white cultural strain” and was tested in vitro for the capacity to convert the virulent isolates by dual culture tests.

Characterization of the chestnut blight canker and the localization and isolation of the pathogen Cryphonectria parasitica

1989 ◽  
Vol 67 (12) ◽  
pp. 3600-3607 ◽  
Author(s):  
Patricia S. McManus ◽  
Frank W. Ewers ◽  
Dennis W. Fulbright
Keyword(s):  
Transverse Section ◽  
Virulent Strain ◽  
Cryphonectria Parasitica ◽  
Chestnut Blight ◽  
Growth Rings ◽  
Double Stranded Rna ◽  
Naturally Occurring ◽  
Xylem Tissue ◽  
Hypovirulent Strain

Naturally occurring chestnut blight cankers on Castanea dentata were categorized as virulent (sunken bark with abundant stromata) or hypovirulent (swollen bark lacking stromata). In transverse section, xylem tissue of virulent cankers was discolored and largely nonconductive. Hypovirulent cankers had anomalous secondary xylem tissue that was light in color and conducted safranin dye, although xylem of the main stem axes of hypovirulent cankers was discolored. In naturally occurring cankers, no correlation was found between canker morphology and the presence or absence of double-stranded RNA in the inciting fungus (Cryphonectria parasitica). However, a virulent strain lacking double-stranded RNA induced cankers that resembled natural virulent cankers, and inoculation with a known hypovirulent strain containing double-stranded RNA resulted in swollen cankers that resembled natural hypovirulent cankers. Cryphonectria parasitica was isolated from all growth rings of virulent cankers and from the discolored xylem tissue of hypovirulent cankers but not from the conductive anomalous xylem tissue of hypovirulent cankers. Hyphae were observed via fluorescence microscopy in the xylem of natural and induced virulent cankers but not in hypovirulent cankers, whether natural or induced by artificial means.

Effects of water stress on chestnut blight

1995 ◽  
Vol 25 (6) ◽  
pp. 1030-1035 ◽  
Author(s):  
S. Gao ◽  
L. Shain
Keyword(s):  
Water Stress ◽  
Osmotic Potential ◽  
Virulent Strain ◽  
Moisture Stress ◽  
Companion Paper ◽  
Culture Collection ◽  
Chestnut Blight ◽  
Chestnut Blight Fungus ◽  
Dormant Season ◽  
Stem Segments

A range of moisture stress was induced in American chestnut (Castaneadentata (Marsh.) Borkh.) stem segments by incubating them in chambers maintained at humidities of 100%, 90%, or 70% or by soaking their unsealed lower ends in water. Stems then were inoculated with mycelial discs or conidial suspensions of a virulent strain of the chestnut blight fungus (Cryphonectriaparasitica (Murr.) Barr, Ep 155 (American Type Culture Collection No. 38755)). Bark osmotic potential and relative turgidity were monitored on these stems during the development of chestnut blight cankers. Canker expansion was greatest on the stem segments that were lowest in bark osmotic potential (−1.8 MPa) and relative turgidity (56.3%), whereas expansion was least on those stems that were highest in bark osmotic potential (−1.1 MPa) and relative turgidity (68.4%). Water stress, however, had little effect on conidial infection of wounds on stems collected during the growing season, but fewer conidial inoculations of wounds were successful on water-stressed stems collected during the dormant season. Bark osmotic potential of living trees ranged from −0.8 to −2.0 MPa in monthly samplings during the year. Mycelial growth and conidial germination of C. parasitica generally was not affected at osmotic potentials above −2.0 MPa (see companion paper). These results indicate that canker expansion, but not necessarily canker initiation, is favored by water stress and that the effects of water stress are greater on the host than on the pathogen.

Measuring resistance of chestnut trees to chestnut blight

1992 ◽  
Vol 22 (4) ◽  
pp. 568-571 ◽  
Author(s):  
Sandra L. Anagnostakis
Keyword(s):  
Quantitative Assessment ◽  
First Generation ◽  
Chinese American ◽  
American Chestnut ◽  
Chestnut Blight ◽  
Japanese American ◽  
Individual Tree ◽  
Chestnut Blight Fungus ◽  
Tree Resistance ◽  
Virulent Strains

Four species of chestnut trees and four kinds of hybrids were inoculated with two virulent strains of the chestnut blight fungus (Cryphonectriaparasitica (Murr.) Barr). Rate of canker expansion was measured over 114 days (June–September), and rate change was used as a quantitative assessment of individual tree resistance. Cankers on two typical American chestnut trees (Castaneadentata (Marsh.) Borkh.) expanded at a rate of 1 mm/day. Expansion rates on Chinese chestnut (Castaneamollissima Blume) ranged from 0.2 to 0.6 mm/day, and the rates on two Japanese chestnut trees (Castaneacrenata Siebold & Zucc.) were 0.08 to 0.2 mm/day. Our single Henry chestnut (Castaneahenryi (Skan) Reh. & Wilson) tree allowed rates of 0.3 and 0.8 mm/day. Most rates on American–Chinese and Japanese–American hybrids were from intermediate between rates on Asian and American trees to near the rates on American trees. However, a first-generation backcross of Chinese–American × American only allowed expansion rates of 0.3 and 0.4 mm/day, similar to the lowest rates on Asian trees.

Movement of cytoplasmic hypovirulence agents in chestnut blight cankers

1992 ◽  
Vol 70 (3) ◽  
pp. 557-561 ◽  
Author(s):  
L. Shain ◽  
J. B. Miller
Keyword(s):  
Biological Control ◽  
Key Words ◽  
Cryphonectria Parasitica ◽  
Castanea Dentata ◽  
American Chestnut ◽  
Chestnut Blight ◽  
Typical Morphology ◽  
Natural Range ◽  
Hypovirulent Strain ◽  
Endothia Parasitica

Chestnut blight cankers, initiated with virulent methionine auxotrophic strains of Cryphonectria parasitica, were challenged by placing one or two discs of agar and mycelium of prototrophic hypovirulent strains at their base. Movement of hypovirulence agents was confirmed by recovery of an isolate that exhibited the typical morphology of the introduced hypovirulent strain on media with methionine but little or no growth on media without methionine. Cultures from bark showed that the hypovirulent agent moved through mycelium around the circumference of cankers within 3 weeks when the virulent and challenging hypovirulent were vegetatively compatible. Conversion of the mycelium in the canker interior proceeded more slowly. Conversion of mycelium also was delayed, but eventually occurred, when virulent and hypovirulent inocula differed in vegetative compatibility. Conidia, however, continued to yield virulent, methionine-requiring cultures up to 65 weeks after challenge, even though underlying bark frequently yielded hypovirulent, methionine-requiring cultures. This disinclination of hypovirulent agents to enter the asexual apparatus in cankers may contribute substantially to the observed ineffective dissemination of hypovirulence in the natural range of American chestnut. Exploitation of those hypovirulent agents that can enter conidia in cankers may enhance the biological control of chestnut blight by hypovirulence. Key words: biological control, Cryphonectria parasitica, Endothia parasitica, Castanea dentata.

Evaluation of the growth and sporulation of different entomopathogenic fungi in different liquid and solid media at varied concentrations

2017 ◽  
Vol 6 (8) ◽  
pp. 5459
Author(s):  
Chandra Teja K. ◽  
Rahman S. J.
Keyword(s):  
Entomopathogenic Fungi ◽  
Large Scale ◽  
Insect Pests ◽  
Culture Media ◽  
Virulent Strain ◽  
Carbon Sources ◽  
Nitrogen Sources ◽  
Maximum Growth ◽  
Nutritional Requirements ◽  
Virulent Strains

Entomopathogenic fungi like Beauveria bassiana, Metarhizium anisopliae and Lecanicillium lecanii are used in biological control of agricultural insect pests. Their specific mode of action makes them an effective alternative to the chemical Insecticides. Virulent strains of Entomopathogenic fungi are effectively formulated and used as bio-insecticides world-wide. Amenable and economical multiplication of a virulent strain in a large scale is important for them to be useful in the field. Culture media plays a major role in the large-scale multiplication of virulent strains of Entomopathogens. Different substrates and media components are being used for this purpose. Yet, each strain differs in its nutritional requirements for the maximum growth and hence it is necessary to standardize the right components and their optimum concentrations in the culture media for a given strain of Entomopathogen. In the current study, three different nitrogen sources and two different carbon sources were tried to standardize the mass multiplication media for seven test isolates of Entomopathogenic fungi. A study was also conducted to determine the ideal grain media for the optimum conidial yields of the test isolates. Yeast extract was found to be the best Nitrogen source for the isolates. The isolates tested, differed in their nutritional requirements and showed variation in the best nitrogen and carbon sources necessary for their growth. Variation was also found in the optimum concentration of both the ingredients for the growth and sporulation of the isolates. In the solid-state fermentation study, rice was found to be the best grain for the growth of most of the fungi followed by barley. The significance of such a study in the development of an effective Myco-insecticide is vital and can be successfully employed in agriculture is discussed.

scholarly journals In Vitro Activities of Garenoxacin (BMS-284756) against 170 Clinical Isolates of Nine Pasteurella Species

2002 ◽  
Vol 46 (9) ◽  
pp. 3068-3070 ◽  
Author(s):  
Ellie J. C. Goldstein ◽  
Diane M. Citron ◽  
C. Vreni Merriam ◽  
Yumi A. Warren ◽  
Kerin L. Tyrrell ◽  
...  
Keyword(s):  
Pasteurella Multocida ◽  
Active Agent ◽  
Culture Collection ◽  
Clinical Isolates ◽  
American Type Culture Collection ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Agar Dilution

ABSTRACT The in vitro susceptibilities of 170 clinical isolates plus 12 American Type Culture Collection strains of Pasteurella species comprising nine species and three Pasteurella multocida subspecies were studied by an agar dilution method. Garenoxacin (BMS-284756), a new des-fluoro(6) quinolone, was active at ≤0.06 μg/ml against all isolates, including four β-lactamase-producing strains, with >90% of the strains susceptible to ≤0.008 μg/ml. Garenoxacin was generally 1 to 2 dilutions more active than levofloxacin and moxifloxacin and was the most active agent tested. Cefoxitin required 1 μg/ml for inhibition of 51 of 182 (29%) of strains, and 3 strains (also β-lactamase producers) were resistant to doxycycline.

Sign in / Sign up

Export Citation Format

Share Document