Variation in endophytic fungi from roots and leaves of <i>Lepanthes</i> (Orchidaceae)

Bayman, Paul; Lebrón, Ligia; Tremblay, Raymond L.; Lodge, D. Jean

doi:10.1046/j.1469-8137.1997.00618.x

Cited by 138 publications

(88 citation statements)

References 25 publications

(41 reference statements)

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“…Cabral et al 7) showed that epiphytic fungi can sometimes invade the substomatal chambers of living leaves and Petrini 31) speculated that such fungi might be able to enter living leaves of plants under stress. Colletotrichum, Phomopsis, Phyllosticta and Xylaria are ubiquitous forms isolated from a broad range of host plants in the tropics 5,17,30) . In a study on fungal communities of dry thorn and deciduous forest trees in Southern India, Suryanarayanan et al 47) recovered Phyllosticta and Phomopsis as dominant fungi from 20 of 24 host plants studied.…”

Section: Resultsmentioning

confidence: 99%

Fungal Communities in Herbaceous Medicinal Plants from the Malnad Region, Southern India

2008

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Fungal communities were isolated from surface sterilized leaf segments of nine ethnopharmaceutically important medicinal herbs collected from the Bhadra River Project Area, the Malnad region, Southern India. A total of 2159 isolates belonging to 55 different fungal species were isolated from 3600 leaf segments collected during the wet and dry seasons. Chaetomium globosum (7.3%), Aureobasidium pullulans (6.1%), Cladosporium cladosporioides (3.9%), Curvularia lunata (1.9%), Nigrospora oryzae (1.7%), Alternaria alternata (1.3%), Botryosphaeria subglobosa (1.1%), Phoma multirostrata (0.9%), Aspergillus niger (0.8%), Fusarium oxysporum (0.7%), Rhizoctonia solani (0.4%), and Sphaeropsis sapenea (0.3%) were the most frequently isolated fungal species. Colonization rates of fungal species varied significantly between the two seasons. Host specificity was observed in some host plants.Key words: diversity, fungi, medicinal herbs, seasonality, Malnad Region Plant and microbial symbiotic interactions and how these interactions influence plant communities and environments have been well explored 6,10,22) . Rhizospheric and mycorrhizal associations play a major role in physiological and biochemical properties owing to the growth and ecological fitness of hosts 15) . Microbes like bacteria and fungi which live inside healthy plant tissues without causing apparent symptoms, known as endophytes 33) are also known to form mutually beneficial relationships with their hosts 23) . Being mutualists, these microbial populations are known to be beneficial to host plants by enhancing the absorption of soil nutrients such as phosphorus and other inorganic elements, nitrogen-fixing efficiency 38,43) and plant growth with the production of hormones like auxins, abscisins, ethylene, gibberellins, and kinetins 20,29) . They provide protection to their hosts against insect pests 27) , herbivores 11) , and microbial pathogens 39,42,44) . Fungi present in healthy tissues of plants can promote the invasion of host plant communities with greater species diversity 37) and alter the nutrient cycle in individual plants 18) and in ecosystems 24) . The isolation and characterization of fungal communities will help us to estimate the diversity of fungi 2) , since the true scale of fungi is open to debate 21,26) . Most importantly, fungi isolated from healthy tissues may be a source of various secondary metabolites, alkaloids, and biologically active compounds 35,45) . Bacterial endophytes have been screened from many agricultural, horticultural and forest plant species 1,23,25,28) . In India, medicinal plants have long been used in the ailment of various diseases. In view of the importance of microbial populations which live inside healthy plant tissues, we investigated the distribution of fungal communities and seasonal colonization patterns in medicinal herbs of the Malnad Region, Karnataka state, Southern India. Materials and methods Sample collectionThe leaf samples of Catharanthus roseus India, which is a part of the Western Ghat region, a hot spo...

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Section: Resultsmentioning

confidence: 99%

Fungal Communities in Herbaceous Medicinal Plants from the Malnad Region, Southern India

2008

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“…There are numerous reports of pathogenic Colletotrichum spp. that form endophytic and epiphytic associations with plants (2,45,52). Some, such as C. gloeosporioides, C. acutatum, and C. magna, are described as pathogens of one host and asymptomatic endophytes of other species (15,44,48).…”

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Root Infection and Systemic Colonization of Maize byColletotrichum graminicola

Sukno

García

Shaw

et al. 2008

Appl Environ Microbiol

109

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Colletotrichum graminicola is a filamentous ascomycete that causes anthracnose disease of maize. While the fungus can cause devastating foliar leaf blight and stalk rot diseases, little is known about its ability to infect roots. Previously published reports suggest that C. graminicola may infect maize roots and that root infections may contribute to the colonization of aboveground plant tissues, leading to disease. To determine whether C. graminicola can infect maize roots and whether root infections can result in the colonization of aboveground plant tissues, we developed a green fluorescent protein-tagged strain and used it to study the plant root colonization and infection process in vivo. We observed structures produced by other root pathogenic fungi, including runner hyphae, hyphopodia, and microsclerotia. A mosaic pattern of infection resulted from specific epidermal and cortical cells becoming infected by intercellular hyphae while surrounding cells were uninfected, a pattern that is distinctly different from that described for leaves. Interestingly, falcate conidia, normally restricted to acervuli, were also found filling epidermal cells and root hairs. Twenty-eight percent of plants challenged with soilborne inoculum became infected in aboveground plant parts (stem and/or leaves), indicating that root infection can lead to asymptomatic systemic colonization of the plants. Many of the traits observed for C. graminicola have been previously reported for other root-pathogenic fungi, suggesting that these traits are evolutionally conserved in multiple fungal lineages. These observations suggest that root infection may be an important component of the maize anthracnose disease cycle.

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“…Other common orders colonizing the roots included Sordariales, Xylariales, and Agaricales. By contributing to drought tolerance and nutrient acquisition, DSF may be integral to the function of arid ecosystems.Symbiotic associations of fungi and plants are ancient and phylogenetically diverse (4,9,11,42,43,60,64,69). Some of these fungi, notably mycorrhizal fungi, have received extensive study, but accumulating evidence indicates that many of the fungi associated with plant roots are dark septate fungi (DSF).…”

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Novel Root Fungal Consortium Associated with a Dominant Desert Grass

Porras-Alfaro

Herrera

Sinsabaugh

et al. 2008

Appl Environ Microbiol

197

149

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The broad distribution and high colonization rates of plant roots by a variety of endophytic fungi suggest that these symbionts have an important role in the function of ecosystems. Semiarid and arid lands cover more than one-third of the terrestrial ecosystems on Earth. However, a limited number of studies have been conducted to characterize root-associated fungal communities in semiarid grasslands. We conducted a study of the fungal community associated with the roots of a dominant grass, Bouteloua gracilis, at the Sevilleta National Wildlife Refuge in New Mexico. Internal transcribed spacer ribosomal DNA sequences from roots collected in May 2005, October 2005, and January 2006 were amplified using fungal-specific primers, and a total of 630 sequences were obtained, 69% of which were novel (less than 97% similarity with respect to sequences in the NCBI database). B. gracilis roots were colonized by at least 10 different orders, including endophytic, coprophilous, mycorrhizal, saprophytic, and plant pathogenic fungi. A total of 51 operational taxonomic units (OTUs) were found, and diversity estimators did not show saturation. Despite the high diversity found within B. gracilis roots, the root-associated fungal community is dominated by a novel group of dark septate fungi (DSF) within the order Pleosporales. Microscopic analysis confirmed that B. gracilis roots are highly colonized by DSF. Other common orders colonizing the roots included Sordariales, Xylariales, and Agaricales. By contributing to drought tolerance and nutrient acquisition, DSF may be integral to the function of arid ecosystems.Symbiotic associations of fungi and plants are ancient and phylogenetically diverse (4,9,11,42,43,60,64,69). Some of these fungi, notably mycorrhizal fungi, have received extensive study, but accumulating evidence indicates that many of the fungi associated with plant roots are dark septate fungi (DSF). These fungi are usually described as endophytes, whose functions have only recently been studied (43,44,76). DSF comprise a taxonomically diverse group (34, 37) characterized by melanized septate hyphae. Endophytes with hyaline hyphae are also common (e.g., see references 48, 53, and 76), but are less well characterized, because they are more difficult to detect in microscopic analysis and are sometimes considered contaminants in mycorrhizal fungal studies. Growing evidence showing the broad distribution and high root colonization rates of DSF in different ecosystems suggests that their functional importance may rival that of arbuscular mycorrhizal fungi (AMF) (1, 43), particularly for plants growing in stressed environments, such as alpine habitats and arid grasslands (8, 45a, 54, 56, 75). In these habitats, endophytic DSF and other rootassociated fungi allow some plants to increase their resistance to drought and heat and facilitate the acquisition of nutrients (23, 43, 45a, 50, 57, 76, 81).Desert environments are one of the most challenging ecosystems for plants and microorganisms (18,51,87). Biological activity, dive...

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Variation in endophytic fungi from roots and leaves of Lepanthes (Orchidaceae)

Cited by 138 publications

References 25 publications

Fungal Communities in Herbaceous Medicinal Plants from the Malnad Region, Southern India

Fungal Communities in Herbaceous Medicinal Plants from the Malnad Region, Southern India

Root Infection and Systemic Colonization of Maize byColletotrichum graminicola

Novel Root Fungal Consortium Associated with a Dominant Desert Grass

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