Endophytic fungi

Cinchona alkaloids have been used as drugs for the treatment of several diseases. Quinine is very popular as an antimalarial drug against the erythrocyte stage of the parasite [34]. Recently, Shibuya et al. (2003) reported the microbial transformation of four Cinchona alkaloids (quinine, quini-dine, cinchonidine, and cinchonine) by endophytic fungi isolated from Cin-... 

Bills, G. F. (1994) in Systematics, Ecology and Evolution of Endophytic Fungi in Grasses and Woody Plants, ed. Redlin, S. C. (APS Press, St. Paul), in press. 

Fig. 17 Guanacastepenes (187-201) produced by endophytic fungi from Daphnopsis amercina...

Schulz B, Boyle C, Draeger S, Rommert AK, Krohn K, Endophytic fungi A source of novel biologically active secondary metabolites, MycolRes 106 996—1004,2002. 

Stierle A, Strobel G, Stierle D, Grothaus P, Bignami G, The search for a taxol-producing microorganism among the endophytic fungi of the pacific yew, Taxus brevifolia, JNat Prod 58 1315-1324, 1995. 

Stierle A, Stierle D, Strobel G, Bignami G, Grothaus P, Endophytic fungi of pacific yew Taxus brevifolia) as a source of taxol, taxanes and other pharmacophores, in Bioregulators for Crop Protection and Pest Control, American Chemical Society, Washington DC, pp. 64—77, 1994. 

There are a number of recent reviews of endophytes, both bacterial and fungal, and their secondary metabolism that would provide the interested reader with further details and background. Among these are the excellent reviews concerning the interaction between the endophyte and the host, as well as those that specifically address the bioactive natural product production by endophytic fungi.The latter collectively list over 330 different compounds produced. To the extent that is reasonable, I have chosen not to repeat the information in these recent reviews, but to summarize their findings (Table 1). This review will address the information from the more recent literature and, insofar as is known, details of biosynthesis. 

Several roles of endophytic fungi for the host plant have been postulated. These include acting to increase access to mineral nutrients (a mycorrhizal function), to increase access to organic soil N, P and C, to increase drought and stress tolerance, to improve water uptake, protection from herbivory (mammals, insects), and for protection from plant pathogenic fungi, bacteria, nematodes, and other parasites. We should not be surprised that endophytic fungi are such common plant symbioses. 

As stated previously, the products of endophytic fungi have been the subject of previous reviews. The compounds addressed previously are summarized in Table 1. Clearly, the compounds are chemically diverse and display a wide range of biological activities. 

Table 1. Bioactive fungal products from endophytic fungi in recent literature reviews. The compounds include antifungal, antibacterial, antimycobacterial, antiviral, nematicidal, cytotoxic, antineoplastic, antioxidant, antiinsectant, antifeedant, antidiabetic, herbicidal, algicidal, specific en mie inhibitory, and immunomodulatory activities. 

A search was undertaken to discover endophytic fungi in marine algae and plants in the regions of Gottingen and Braunschweig in Germany. In... 

General mineral nutrition status improvement for the host plant has been studied frequently to understand the roles of endophytic fungi. Iron nutrition, however, has been studied only occasionally. P. fortinii strains obtained from Pinus sylvestris, Abies alba, Picea abies, and Carex curvula (the last a monocotyledonous plant) were found to produce the cyclic hexapeptide siderophores ferricrocin (73), ferrirubin (74) and ferrichrome C (75). The concentration and pattern of siderophore production was dependent on ferric ion concentration, pH of the medium, and the strain of endophyte. 

The secondary metabolites of the endophytic fungi associated with dicotyledonous plants (dicots) are chemically diverse (Table 1). There is an equal diversity in the activities of these compounds, including antibacterial, antifungal, nematicidal, phytotoxic, cytotoxic, antineoplastic, anti-insectant, anti-herbivory, and a variety of other activities. The compounds isolated, structurally elucidated, and explored biologically in the short time since previous reviews continue to display that same wide array of chemical and biological diversity. 

Studies continue to be published in which only the results of bioassay of fungal extracts are presented without the identification of active compounds. Some of these studies suggest significant activities for the compounds contained in the extracts. Such studies represent opportunities for the natural products chemist to collaborate with the biology- and molecular biology-oriented groups for more complete studies of the plants and associated endophytic fungi. 

An interesting new area of work is the biotransformation of plant products to new compounds by their endophytic fungi. A known allelopathic compound, lepidimoide, was synthesized by an endophytic Colletotrichum sp. from okra Hibiscus esculentus) polysaccharide [(1 —> 4) — O — a-(D-galactopyranosyluronic acid)-(l - 2) —O — a-L-rhamopyranose]... 

Pinto LSRC et al.. Symptomless infection of banana and maize by endophytic fungi impairs photosynthetic efficiency. New Phytol 147 609—615, 2000. 

Mandyam K, Jumpponen A, Seeking the elusive function of the root-colonising dark septate endophytic fungi. Stud Mycol 53 173-189, 2005. 

Ganjah R etal., Classical methods and specific primers in detection of endophytic fungi in some gramineuos plants, Rostaniha 5 15—18, 2004. 

Saha DC et al., A rapid staining method for detection of endophytic fungi in turf and forage grasses. Phytopathology 78 237—239, 1988. 

Jure M et ai, Ergosterol content of endophytic fungi from the needles of the Austrian pine Pinus nigra hirsl),Acta Biol Sloven 41 23—33, 1997. 

---