The Promotion of Festuca sinensis under Heavy Metal Treatment Mediated by Epichloë Endophyte

To more clearly clarify the relationship between the Epichloë endophyte and its host, F. sinensis, the effects of Epichloë endophyte on F. sinensis performance under heavy metal treatment was investigated. The growth performance and physiology variations of F. sinensis with (E+) and without the endophyte (E−) were evaluated after they were subjected to Zn2+ and Cd2+ treatments. The results showed that heavy metal treatments had significant effects on plants, as the performance of plants under Zn2+ and Cd2+ treatments was significantly different with plants under control treatment (p < 0.05). Cd2+ treatments showed a hormesis effect, whereas Zn2+ did not. The endophyte increased host heavy metal stress tolerance by promoting host growth as the E+ plants had significantly higher plant height, tiller number, root length (p < 0.05). The endophyte also promoted ion uptake by the host and induced endogenous hormone production (p < 0.05). These results suggested that the Epichloë endophyte regulated host growth and physiology to improve association tolerance to environmental conditions. This study provides another example that the Epichloë endophyte can increase plant tolerance to metal stress.

Different response of perennial ryegrass—Epichloë endophyte symbiota to the elevated concentration of heavy metals in soil

The phenomenon of plant mutualistic symbiosis with microbes may have a positive effect on the improvement of plant tolerance to environmental stresses as well as on the ability of plants to accumulate heavy metal (HM) ions from soil. The influence of Epichloë fungal endophyte (Ascomycota, Clavicipitaceae) on perennial ryegrass (Lolium perenne L.) plants grown in the presence of elevated concentrations of HM ions (Cd2+, Pb2+, and Cu2+) in soil was studied. The presence of Epichloë in the host grass tissues resulted in different accumulation of HM ions in the aboveground parts of the plants. In some cases, endophyte infection positively affected ryegrass ability to accumulate HM ions from soil. In plants with (E +) and without (E −) endophytes, the hormesis effect was induced by the elevated concentration of Cu2+ ions, resulting in better growth and photosynthesis, as examined by measurements of Chl a fluorescence. The obtained results indicate that based on the laboratory evaluation of the efficiency of HM accumulation, we were able to choose the best associations of perennial ryegrass with endophytes for HM phytoremediation.

The Plant Salicylic Acid Signalling Pathway Regulates the Infection of a Biotrophic Pathogen in Grasses Associated with an Epichloë Endophyte

The study of the contribution of the plant defence hormones, salicylic acid (SA) and jasmonic acid (JA), in the resistance against pathogens of plants associated with Epichloë fungal endophytes has been scanty. We hypothesised that Epichloë spp., capable of inducing host plant SA-dependent defences, would increase the levels of plant resistance against biotrophic pathogens. Plants of Achnatherum inebrians, with and without the fungal endophyte Epichloë gansuensis, were inoculated with the biotrophic fungal pathogen Blumeria graminis. We measured the status of plant defences (associated with SA and JA signalling pathways) and the levels of resistance to the pathogen. Plants associated with the endophyte showed less disease symptoms caused by the biotrophic pathogen than plants without the endophyte. In agreement with our hypothesis, the Epichloë endophyte increased the plant production of SA and enhanced the expression levels of plant genes of synthesis and response to the SA hormone. The elevated expression of SA-related genes coding for putative plant enzymes with anti-fungal activities promoted by the endophyte may explain the enhanced resistance to the pathogen. The present study highlights that interaction between the plant immune system and Epichloë fungal endophytes can contribute significantly to the resistance of endophyte-symbiotic plants against pathogens.

Different Response of Perennial Ryegrass – Epichloë Endophyte Symbiota to the Elevated Concentration of Heavy Metals in Soil

The phenomenon of plant mutualistic symbiosis with microbes may have a positive effect on the improvement of plant tolerance to environmental stresses as well as on the ability of plants to accumulate heavy metal (HM) ions from soil. The influence of Epichloë fungal endophyte (Ascomycota, Clavicipitaceae) on perennial ryegrass (Lolium perenne L.) plants grown in the presence of elevated concentrations of HM ions (Cd2+, Pb2+ and Cu2+) in soil was studied. The presence of Epichloë in the host grass tissues resulted in different accumulation of HM ions in the aboveground parts of the plants. In some cases endophyte infection positively affected ryegrass ability to accumulate HM ions from soil. In plants with (E+) and without (E-) endophytes the hormesis effect was induced by the elevated concentration of Cu2+ ions, resulting in better growth and photosynthesis, as examined by measurements of Chl a fluorescence. The obtained results indicate that based on the laboratory evaluation of the efficiency of HM accumulation, we were able to choose the best associations of perennial ryegrass with endophytes for HM phytoremediation.

The Impact of Alkaloid-Producing Epichloë Endophyte on Forage Ryegrass Breeding: A New Zealand Perspective

For 30 years, forage ryegrass breeding has known that the germplasm may contain a maternally inherited symbiotic Epichloë endophyte. These endophytes produce a suite of secondary alkaloid compounds, dependent upon strain. Many produce ergot and other alkaloids, which are associated with both insect deterrence and livestock health issues. The levels of alkaloids and other endophyte characteristics are influenced by strain, host germplasm, and environmental conditions. Some strains in the right host germplasm can confer an advantage over biotic and abiotic stressors, thus acting as a maternally inherited desirable ‘trait’. Through seed production, these mutualistic endophytes do not transmit into 100% of the crop seed and are less vigorous than the grass seed itself. This causes stability and longevity issues for seed production and storage should the ‘trait’ be desired in the germplasm. This makes understanding the precise nature of the relationship vitally important to the plant breeder. These Epichloë endophytes cannot be ‘bred’ in the conventional sense, as they are asexual. Instead, the breeder may modulate endophyte characteristics through selection of host germplasm, a sort of breeding by proxy. This article explores, from a forage seed company perspective, the issues that endophyte characteristics and breeding them by proxy have on ryegrass breeding, and outlines the methods used to assess the ‘trait’, and the application of these through the breeding, production, and deployment processes. Finally, this article investigates opportunities for enhancing the utilisation of alkaloid-producing endophytes within pastures, with a focus on balancing alkaloid levels to further enhance pest deterrence and improving livestock outcomes.