Gray Mold Fungus Research Articles

Putative virulence factors of Botrytis cinerea acting as a wound pathogen

The grey mold fungus, Botrytis cinerea, is a wound pathogen of worldwide distribution, and causes rots of almost all fruits and vegetables. The fungus can also penetrate directly from appressoria to cause severe losses to growers of flowers. B. cinerea secretes a number of inducible attack enzymes which can degrade host cell walls to widen the infection, including β-glucosidase, pectin methylesterase, the polygalacturonases, and aspartate proteinase; laccase and benzyl alcohol oxidase appear to have roles of detoxifying compounds derived from the host during pathogenesis, a function that we believe enhances the virulence of the pathogen. With additional research, several oxidases may also become a part of the virulence group. Much more work is needed, in particular the analysis of mutants, to assign formally the roles suggested here.

北海道各地から分離した豆類灰色かび病菌のフルアジナムに対する感受性

北海道各地から分離した豆類灰色かび病菌のフルアジナムに対する感受性

The phytoalexin response of lettuce to challenge by Botrytis cinerea, Bremia lactucae and Pseudomonas syringae pv. phaseolicola

Lettucenin A was confirmed to be the principal phytoalexin in lettuce. The accumulation of lettucenin A was directly related to the number of cells undergoing the hypersensitive reaction (HR) during incompatible interactions with Bremia lactucae governed by the Dm5/8 and Dm7 resistance genes. Very little phytoalexin accumulation occurred during the successful colonization of cotyledons by a virulent isolate of B. lactucae. The HR to Pseudomonas syringae pathovar phaseolicola was also associated with the localized accumulation of lettucenin A. Inoculation of leaves with conidia of Botrytis cinerea caused the formation of limited lesions within which fungal growth was restricted. Lettucenin A reached high concentrations in tissue bearing limited lesions and within inoculum droplets on the leaf surface. Mycelial inocula of B. cinerea produced spreading lesions. During successful colonization by B. cinerea an initial increase in lettucenin A concentration at infection sites was followed by a decrease as tissue became completely colonized and rotted by the grey mould fungus. The success or failure of B. cinerea to invade lettuce appeared to be based on a balance between phytoalexin accumulation and degradation. Lettucenin A at 10−6 m concentrations was found to possess considerable activity against B. lactucae, B. cinerea and P. syringae pv. phaseolicola and probably has an important role in the resistance of lettuce tissues to microbial colonization.

A rapid method to estimate the resistance of cold stored carrot roots to Botrytis cinerea

SUMMARYInoculating whole carrot roots at 4°C with mycelial/agar discs of the grey mould fungus Botrytis cinerea gives a measure of their resistance and hence storage potential to this pathogen, but results are not obtained for at least 33 days. In the present investigation a more rapid method was used which involved inoculating root slices with spore suspensions containing 5 × 103–5 × 106 spores/cm3 at 24°C. Resistance was assessed visually and by a chitin estimation 48 h after inoculation.Both methods were used to measure the resistance of cold stored carrot roots during two storage seasons, 1976/77 and 1977/78. In each season there was a particular inoculum level which most clearly recorded the increasing susceptibility of roots with time in store. In 1976/77 this was 1 × 105 spores/cm3 whereas in 1977/78 it was the lower inoculum concentration of 5 × 104 spores/cm3, suggesting the roots were generally more susceptible in 1977/78 than the previous season. This was in accord with the results from the whole root method of assessment. A chitin estimation proved to be the more sensitive method of assessment for inoculum potential experiments.

Stimulative effects of purines and their relative compounds on lesion formation of gray mold on cucumber plant.

Purine and their relative compounds were found to accelerate the infection and lesion formation caused by gray mold fungus, Botrytis cinerea, on cucumber seedling in the presence of glucose at the concentration more than 2.5%. The required concentration of all these compounds for exhibiting their action on the gray mold fungus to accelerated the infection and lesion formation were more than 1×10-5M. All pyrimidines, however, were not effective, even at the concentration of 1×10-3M. Among the purines, the tri- and the mono-phosphates were much more effective; whereas the free bases and the diphosphates were somewhat less effective. Some metabolites of purines, uric acid, allantoin and allantoic acid were considerably effective as well as that of ATP and AMP.

Tolerance of strawberry gray mold fungus, Botrytis cinerea, against thiophanatemethyl, polyoxin, and procymidone in Shizuoka Prefecture

Tolerance of strawberry gray mold fungus, <i>Botrytis cinerea</i>, against thiophanatemethyl, polyoxin, and procymidone in Shizuoka Prefecture

Penetration of carrot roots by the grey mould fungus Botrytis cinerea Pers. ex Pers

Infection of carrot roots by Botrytis cinerea at 11 to 14°C was studied by light and electron microscopy. Conidia of the fungus, in nutrient solution on the surface of uninjured carrots, germinated and produced dome-shaped infection cushions in 48 h. Infection cushions were formed by the development and aggregation of hyphae produced by several conidia. Penetration was effected by infection pegs that arose from swollen hyphal tips on the undersides of infection cushions. Occasionally, infection by single germinated conidia in the vicinity of infection cushions was observed; entry was direct via a narrow infection peg. Prior to penetration the peridermal wall layers of the host became swollen and changes occurred in their ultrastructural staining properties. A multivesicular body was present in the fungus near the point of attachment to the host wall where it may have been involved in the enzymic penetration of the host periderm. Evidence for degradation of suberized host walls during penetration is presented and discussed.