Fomannoxin,a phytotoxic metabolite of Fomes annosus: in vitro production,host toxicity and isolation from naturally infected Sitka spruce heartwood

The effect of different culture conditions on growth and production of fomannoxin and the sesquiterpene phytotoxin fomannosin by a single isolate of Fomes annosus was studied. Whereas fomannoxin was produced by actively growing hyphae, fomannosin production was associated with the declinning growth phase of the fungus. The presence of fomannoxin in chloroform extracts from the stained stein heartwood zone of Fomes annosus diseased Sitka spruce trees was established. Fomannosin however was not detected. Toxicity of fomannoxin to germinating seeds and young seedlings of Sitka spruce was demonstrated.     

Tolerance of Fomes annosus isolates to pine oleoresins and pinosylvins

Ten Fomes annosus isolates from pine and ten from non-pine-hosts were subjected to the volatile components of pine oleoresin and to various concentrations of pinosylvin (PS) and pinosylvin monomethyl ether (PSM). Both the volatiles and the PS and PMS significantly reduced growth rate compared with controls. However, no detectable difference existed between the two groups of F. annosus isolates in their reactions to the substances tested.     

Biological control of Fomes annosus by Peniophora gigantea1

Fomes annosus is the most important root pathogen in British forestry. In pine crops, F. annosus is often checked when stumps are naturally colonised by Peniophora gigantea. Experimental inoculation of stumps with P. gigantea reduced infection by F. annosus in first rotation crops and was as effective as chemical stump treatments. In severely diseased pine crops, P. gigantea inoculation reduced but did not eliminate F. annosus. P. gigantea is produced commercially and is used in many pine forests in Britain.     

Studies on isoenzyme polymorphism in Fomes annosus1

33 Isolates of Fomes annosus (Heterobasidion annosum) were analysed for their isoenzyme pattern of the enzyme Lactate Dehydrogenase (E.C. 1.1.1.27), Malate Dehydrogenase (E.C. 1.1.1.38), and Laccase (E.C. 1.10.3.2). For lactate dehydrogenase and malate dehydrogenase, a conspicuously high degree of variation in the isoenzyme pattern was found, indicating a rather high degree of genetic variability in the loci coding for these enzymes. The isoenzyme spectrum of laccase, however, was the same in all the strains which were tested.     

Chemical resistance of Pinus densiflora to Fomes annosus

One compound isolated from the stem wood of Pinus densiflora Sieb. Zucc. is responsible for its resistance to Fomes annosus (Fr.) Cke. From thin layer chromatography and microanalytical evidence, the inhibitory compound is nitrogenous and may be an alkaloid.     

The effect of L-threonine on oxalic acid synthesis by Fomes annosus

Addition of 1 mM L-threonine to the growth medium of Fomes annosus inhibited its glyoxylate deliydrogenase activity and the synthesis of oxalic acid. Malate synthetase was synthesized de novo in the presence of L-threonine. Lignosulfonate completely blocked the effect of the amino acid in both glucose or cellobiose-containing medium.     

A Study of Losses in Scots Pine caused by Fomes annosus

Data are presented from unreplicated Scots pine {Pinus sylvestrisL.) sample plots in Thetford Forest which have been differentiallyattacked by Fomes annosus (Fr.) Cooke. Volume production ofseverely infested crops differs markedly from that forecastby management tables. The volume of dead trees may not representthe total loss of volume in these plots as there appears alsoto be a reduction in the growth of the remaining live trees.These observations may have considerable significance in forecastingfuture volume production from stands attacked by F. annosusand also in deciding the optimum time for their replacement.     

Induction of morphogenesis,branching and conidiogenesis in Fomes annosus

In Fomes annosus the addition of L-threonine induces specifically branching and septum formation in the leading hyphae of the mycelium. The formation of conidia is stimulated by the combination of light and dark phases and starvation.     

The mating system of Fomes annosus (Heterobasidion annosum)

Conditions are described which allow reproducible formation of fruiting bodies of Fomes annosus under sterile conditions, suitable for genetic studies. Analysis of the progeny of a fruiting body isolated from woods revealed a bipolar mechanism of genetic control of fruiting body formation as well as “Grenz-haut”-formation.     

Antagonists of Fomes annosus in the rhizosphere of grey alder (Alnus incana) and Norway spruce (Picea abies)

A comparison was made of the fungistatic effects of the root microflora of grey alder and Norway spruce with Fomes annosus as test fungus. The significantly higher frequency of actinomycetes in the alder rhizosphere probably constituted the main difference in this respect. The importance of fungi seemed to be about equal in the rhizosphere of the two tree species. Methods for studies of antagonism are tested and discussed.     

An Experiment to Control Fomes annosus in Second Rotation Pine Crops

Stump removal was found to singnificantly reduce killing byFomes annosus in second rotation crops of pine. Poisoning andgirdling of trees prior to felling and also stump poisoningfailed to control the disease. In this experiment no significantdifferences were detected in the susceptibility of Scots andCorsican pine to attack. Increasing periods of delay beforereplanting resulted in less mortality. An equation is presented,based on factors of the first rotation crop which may be usedto predict losses likely to occur when a site is replanted.Root attack by F. annosus results in reduced growth and yieldas well as mortality. The results from the experiment are discussed in trems of themangement of pine crops attacted by F. annosus in Theford Chase.     

Some observations on the longevity of Fomes annosus in conifer stumps.

The longevity of Fomes annosus in conifer stumps was assessed in 3 investigations, which showed that the fungus could remain active in stumps for periods of 16 to 62 years.     

Identification of some compounds associated with resistance of Pinus densiflora to Fomes annosus

From the heartwood-free stemwood of Pinus densiflora, 7 compounds inhibitory to the linear growth of Fomes annosus were isolated. These were identified as pinosylvin, pinosylvin monomethyl ether, (3-sitosterol, a cembrol-like diterpene alcohol, and three isomeric diterpene acids belonging to the abietane group, one of which is probably palustric acid. Other antifungal fractions contained complex mixtures and were not characterized.     

Mikroskopische Erscheinungsbilder beim Holzabbau durch Fomes annosus (Fr.) Cooke1

Microscopic appearence of wood decomposed by Fomes annosus (Fr.) Cooke . Different stages of decay due to Fomes annosus were studied microscopically. The progress of disintegration is almost the same as that caused by other white rot fungi. Typical features are small zones of enzymatic activity, numerous borcholes of various sizes, and complete dissolution of parts of cellwalls. Pseudoparenchymatous accumulations of mycelium may block tracheids rather like partition walls, and skin-like formations and a great deal of amorphous, or crystalline inclusions may be formed in the lumina of the fibres.     

Examination of metabolic products of the fungus Fomes annosus (Fr.) Cooke

Isolates Fa₁ and Fa₂ of Fomes annosus from naturally infected trees of Picea excelsa (P. abies) and Pinus silvestris, in laboratory conditions synthesized the toxic product formannosine. Identification of the fomannosine was by thin-layer chromatography and infra-red spectrophotometry. Maximum production of the toxic metabolite was found in 80-day-old liquid cultures of isolate Fa₂. The isolate Fa₁ synthesized considerably smaller quantities of fomannosine and other components in all ages of culture and media variants.     

Tree-to tree variation on Picea abies in growth inhibition against Fomes annosus

The spread of Fomes annosus was measured on a set of 20 mature trees which were artificial inoculated. These observations were compared with growth observations and laccase activity of F. annosus grown on wood dust from the same 20 trees. Although variation between Fomes strains as well as between trees was recorded, correspondance between field and laboratory observations was absent in the present material.     

Fomes annosus sporocarps - their abundance on decayed logs left in the forest

On logs of Norway spruce, discarded and left lying after thinning because of severe decay by Fomes annosus, numerous sporocarps of F. annosus develop after one to two years. The surface area, position, number, and time of appearance of the fruiting bodies varied between two test areas. Removal of rotted logs is recommended as a prophylactic method of Fomes control in Picea abies stands.     

Die Wirkung von Monoterpenen auf das Mycelwachstum von Fomes annosus (Fr.) Cooke

The effect of monoterpenes on the mycelial growth of Fomes annosus (Fr.) Cke. Four monoterpenes, singly and in mixture, were tested for their effect on the mycelial growth of Fomes annosus. Inhibition was caused by all the substances, the severity depending on material and concentration. The inhibition was not maintained over the entire study period.     

The influence of chemical factors on the selectivity of Pinus resinosa stumps for Fomes annosus

Compounds such as resins or phenols produced by the host in response to wounding or fungal penetration may play an important role as factors of resistance against Fomes annosus. By extracting stem sections, that were kept for different intervals in a closed chamber, with different organic solvents chloroform produced the most inhibitory extractives against F. annosus. This may explain at least partially the decreasing stump selectivity for F. annosus. Three compounds were isolated from the neutral fractions of chloroform extractives from 24 days wounded wood discs which were found to be different from the compounds in normal and 12 days fractions. Spectrophotometric analyses reveal some characteristics of these isolated compounds, whereas their chemical formula and structure need further investigation.