Effects of osmotic potential on virulent and hypovirulent strains of the chestnut blight fungus

1995 ◽  
Vol 25 (6) ◽  
pp. 1024-1029 ◽  
Author(s):  
S. Gao ◽  
L. Shain
Keyword(s):  
Osmotic Potential ◽  
Mycelial Growth ◽  
Companion Paper ◽  
Conidial Germination ◽  
Chestnut Blight ◽  
Chestnut Blight Fungus ◽  
Virulent Strains ◽  
Agar Media ◽  
Cornmeal Agar ◽  
Osmotic Potentials

Mycelial growth and conidial germination of two virulent and four isogenic hypovirulent strains of Cryphonectriaparasitica (Murr.) Barr were monitored on cornmeal agar media osmotically adjusted with NaCl, KCl, sucrose, or a salt mixture of NaCl–KCl–Na2SO4 of 5:3:2. Mycelial growth generally was not inhibited on KCl or sucrose adjusted media with an osmotic potential above −2.0 MPa. Mycelial growth generally was inhibited at this osmotic potential, however, on those media that contained sodium in the osmoticum. While conidial germination was more sensitive than mycelial growth to sodium, conidia were more tolerant than mycelia to osmotic potentials less than −2.0 MPa when media were adjusted with KCl or sucrose. Conidia of all strains germinated on media adjusted to −6.0 MPa with these two osmotica after incubation for 48 h but not 24 h at 25 °C. Hypovirulent strains generally reacted similarly to their isogenic virulent strains with regard to reduced osmotic potential. Because the lowest osmotic potential of chestnut (Castaneadentata (Marsh.) Borkh.) bark observed in monthly samples was −2.0 MPa (see companion paper), it appears that water stress has little direct impact on the pathogen during pathogenesis.

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.

scholarly journals Use of water restriction in the inoculation of carrot seeds

2019 ◽  
Vol 41 (4) ◽  
pp. 416-422
Author(s):  
Ricardo Borges Pereira ◽  
Tiago B. Torres ◽  
Patrícia Pereira da Silva ◽  
Gilvaine C. Lucas ◽  
Jadir Borges Pinheiro ◽  
...  
Keyword(s):  
Growth Inhibition ◽  
Osmotic Potential ◽  
Mycelial Growth ◽  
Agar Medium ◽  
Potato Dextrose Agar ◽  
Control Treatment ◽  
Infection Rates ◽  
Water Restriction ◽  
Potato Dextrose Agar Medium ◽  
Osmotic Potentials

Abstract: This study aimed at evaluating the method of inoculation of carrot seeds in a potato-dextrose-agar medium (PDA) added of mannitol. Alternaria radicina was the fungus chosen to test such methodology. The osmosis-controlling agent was employed to obtain the osmotic potentials of 0.6 MPa, 0.8 MPa, 1.0 MPa and 1.2 MPa. In comparison with the control treatment, no significant mycelial growth inhibition was noticed at any of the osmotic potentials considered. The seeds were distributed over the fungal colonies for infection, where they remained for 48, 72, 96, 120 and 144 hours, at the osmotic potentials of 0.0 MPa (control), 0.6 MPa, 0.8 MPa, 1.0 MPa and 1.2 MPa, respectively. Tests of germination, sanitization and emergence were performed to evaluate the effects of colonization. Regarding the germination, the different osmotic potentials resulted in similar percentages of abnormal seedlings and dead seeds. As for the sanitization testing, higher infection rates were observed at the osmotic potentials of 1.0 MPa and 1.2 MPa. The lowest percentage of emergence was found at -1.2 MPa, therefore suggesting that this osmotic potential (produced with mannitol) might be used for infecting carrot seeds for research purposes.

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.

scholarly journals Effect of the media on morphology of Cryphonectria parasitica (Murr.) Barr isolates and their Vegetative Compatibility Groups

2015 ◽  
pp. 38-42
Author(s):  
Gabriella Kovács ◽  
László Radócz
Keyword(s):  
Cryphonectria Parasitica ◽  
Vegetative Compatibility ◽  
Bark Extract ◽  
Chestnut Blight ◽  
Vegetative Compatibility Groups ◽  
Infested Area ◽  
Chestnut Blight Fungus ◽  
Virulent Strains ◽  
Different Types ◽  
The Media

The most dangerous pathogen for the European and American chestnuts is the blight fungus Cryphonectria parasitica (Murrill) Barr. Short after its introduction a big number of chestnut trees were destroyed on the infested area. The control could be really complicated, because of the numerous vegetative compatibility groups of the fungus. There is a type that carries a mycovirus viz. hypovirus in the cytoplasm. We are able to control effectively this pathogen by using mycovirus-carrying strains (called hypovirulent fungal strains also). In laboratory it is easy to multiply the virulent and the hypovirulent strains of the fungus but do not easy to differentiate colonies visually on simple PDA medium. During our research, we tested different types of media, based on potato and chestnut bark extract respectively. It was observed that on potato medium the virulent strains produce more orange pigments. So it is more easy to differentiate virulent or hypovirulent isolates of chestnut blight fungus based on colony colour and morphology.

scholarly journals Dynamics of Cryphonectria hypovirus Infection in Chestnut Blight Cankers

2014 ◽  
Vol 104 (9) ◽  
pp. 918-925 ◽  
Author(s):  
Sarah Franziska Bryner ◽  
Simone Prospero ◽  
Daniel Rigling
Keyword(s):  
Virus Infection ◽  
Cryphonectria Parasitica ◽  
Chestnut Blight ◽  
Seedling Mortality ◽  
Chestnut Blight Fungus ◽  
European Chestnut ◽  
Virulent Strains ◽  
Coppice Forest ◽  
Cryphonectria Hypovirus ◽  
Over Time

Virulent strains of the chestnut blight fungus Cryphonectria parasitica cause lethal bark cankers on chestnut trees. Infection of C. parasitica with Cryphonectria hypovirus 1 in Europe biologically controls this disease, leading to nonlethal and inactive cankers. Unexpectedly, virus-free C. parasitica strains have been isolated from inactive cankers. In this study, we compared the virulence of virus-infected and virus-free C. parasitica strains isolated from either inactive or active cankers on chestnut seedlings and sprouts. In the seedling experiment, we assessed canker growth and seedling mortality. In the sprout experiment, we also assessed canker growth and made fungal reisolations to determine virus infection and immigration of foreign vegetative compatibility (vc) types over a period of 13 years in a coppice forest. Overall, the virulence of virus-free C. parasitica strains isolated from inactive versus active cankers did not differ. Significant differences were only attributed to virus infection. Virus infection and fungal strain composition in cankers changed over time. Foreign vc types immigrated into cankers and virus-free cankers became virus-infected within a few years. Most of the cankers were callused over time and became inactive. However, we observed that the virus did not always persist in these cankers. This study demonstrates that virus spread occurs effectively in European chestnut forests and that this biocontrol system is highly dynamic.

scholarly journals Variation in Tolerance and Virulence in the Chestnut Blight Fungus-Hypovirus Interaction

2000 ◽  
Vol 66 (11) ◽  
pp. 4863-4869 ◽  
Author(s):  
Tobin L. Peever ◽  
Yir-Chung Liu ◽  
Paolo Cortesi ◽  
Michael G. Milgroom
Keyword(s):  
Biological Control ◽  
Genetic Variation ◽  
Local Population ◽  
Cryphonectria Parasitica ◽  
Conidial Germination ◽  
Relative Fitness ◽  
Chestnut Blight ◽  
Future Evolution ◽  
Chestnut Blight Fungus ◽  
Fungal Isolates

ABSTRACT Chestnut blight, caused by the fungus Cryphonectria parasitica, has been effectively controlled with double-stranded RNA hypoviruses in Europe for over 40 years. The marked reduction in the virulence of C. parasitica by hypoviruses is a phenomenon known as hypovirulence. This virus-fungus pathosystem has become a model system for the study of biological control of fungi with viruses. We studied variation in tolerance to hypoviruses in fungal hosts and variation in virulence among virus isolates from a local population in Italy. Tolerance is defined as the relative fitness of a fungal individual when infected with hypoviruses (compared to being uninfected); virulence is defined for each hypovirus as the reduction in fitness of fungal hosts relative to virus-free hosts. Six hypovirus-infected isolates of C. parasitica were sampled from the population, and each hypovirus was transferred into six hypovirus-free recipient isolates. The resulting 36 hypovirus-fungus combinations were used to estimate genetic variation in tolerance to hypoviruses, in hypovirus virulence, and in virus-fungus interactions. Four phenotypes were evaluated for each virus-fungus combination to estimate relative fitness: (i) sporulation, i.e., the number of asexual spores (conidia) produced; (ii) canker area on field-inoculated chestnut trees, (iii) vertical transmission of hypoviruses into conidia, and (iv) conidial germination. Two-way analysis of variance (ANOVA) revealed significant interactions (P < 0.001) between viruses and fungal isolates for sporulation and canker area but not for conidial germination or transmission. One-way ANOVA among hypoviruses (within each fungal isolate) and among fungal isolates (within each hypovirus) revealed significant genetic variation (P < 0.01) in hypovirus virulence and fungal tolerance within several fungal isolates, and hypoviruses, respectively. These interactions and the significant genetic variation in several fitness characters indicate the potential for future evolution of these characters. However, biological control is unlikely to break down due to evolution of tolerance to hypoviruses in the fungus because the magnitudes of tolerance and interactions were relatively small.

The chestnut blight fungus world tour: successive introduction events from diverse origins in an invasive plant fungal pathogen

2012 ◽  
Vol 21 (16) ◽  
pp. 3931-3946 ◽  
Author(s):  
C. DUTECH ◽  
B. BARRÈS ◽  
J. BRIDIER ◽  
C. ROBIN ◽  
M. G. MILGROOM ◽  
...  
Keyword(s):  
Fungal Pathogen ◽  
Invasive Plant ◽  
Chestnut Blight ◽  
Chestnut Blight Fungus ◽  
Plant Fungal Pathogen

Comparative vesicle proteomics reveals selective regulation of protein expression in chestnut blight fungus by a hypovirus

2013 ◽  
Vol 78 ◽  
pp. 221-230 ◽  
Author(s):  
Jinzi Wang ◽  
Fangzhen Wang ◽  
Youjun Feng ◽  
Ke Mi ◽  
Qi Chen ◽  
...  
Keyword(s):  
Protein Expression ◽  
Chestnut Blight ◽  
Chestnut Blight Fungus
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