Metabolic Potential of Epichloë Endophytes for Host Grass Fungal Disease Resistance

Abstract

Asexual species of the genus Epichloë (Clavicipitaceae, Ascomycota) form endosymbiotic associations with Pooidae grasses. This association is important both ecologically and to the pasture and turf industries, as the endophytic fungi confer a multitude of benefits to their host plant that improve competitive ability and performance such as growth promotion, abiotic stress tolerance, pest deterrence and increased host disease resistance. Biotic stress tolerance conferred by the production of bioprotective metabolites has a critical role in an industry context. While the known antimammalian and insecticidal toxins are well characterized due to their impact on livestock welfare, antimicrobial metabolites are less studied. Both pasture and turf grasses are challenged by many phytopathogenic diseases that result in significant economic losses and impact livestock health. Further investigations of Epichloë endophytes as natural biocontrol agents can be conducted on strains that are safe for animals. With the additional benefits of possessing host disease resistance, these strains would increase their commercial importance. Field reports have indicated that pasture grasses associated with Epichloë endophytes are superior in resisting fungal pathogens. However, only a few antifungal compounds have been identified and chemically characterized, and these from sexual (pathogenic) Epichloë species, rather than those utilized to enhance performance in turf and pasture industries. This review provides insight into the various strategies reported in identifying antifungal activity from Epichloë endophytes and, where described, the associated antifungal metabolites responsible for the activity.

Historical contingency in parasite community assembly: Community divergence results from early host exposure to symbionts and ecological drift

“…We calculated plant-level infection severity (i.e., parasite infection severity (% leaf area damaged) averaged across leaves within a tracked tiller) for analyses (Fig 1). We used plant-level severity because, even though inoculations were conducted on a single leaf and foliar fungal infections are localized within a leaf [25], E. coenophiala infections and plant immune hormones that are hypothesized to mediate parasite within host interactions are not localized within a leaf [44,45]. Thus, infections of leaves within a plant are not expected to be independent.…”

Analysis of endophytic bacterial diversity in seeds of different genotypes of cotton and the suppression of Verticillium wilt pathogen infection by a synthetic microbial community

“…The prevalence of this disease in cotton has been exacerbated by continuous monoculture, and certain bacterial genera, including Bacillus , Pseudomonas , and Enterobacter , have been proven to contain species that can serve as biological agents against this disease [ 25 , 26 ]. Endophytes isolated from the plant tissues enhance the plant's ability to resist invasion by pathogens [ 27 , 28 ]. The utilization of these beneficial bacteria to construct SynComs is a promising strategy against soilborne pathogens and plant diseases, which can aid in promoting plant health [ 29 ].…”

The Epichloë festucae Antifungal Protein Efe-AfpA Protects Creeping Bentgrass (Agrostis stolonifera) from the Plant Pathogen Clarireedia jacksonii, the Causal Agent of Dollar Spot Disease

“…Other antifungal compounds have been reported from some Epichloë spp. [ 16 , 23 , 24 ], but for commercially produced grasses, the field level disease resistance seen in E. festucae -infected fine fescues is unique.…”