Epichloë fungal endophyte interactions in perennial ryegrass (Lolium perenne L.) modified to accumulate foliar lipids for increased energy density.

BACKGROUND: Commercial cultivars of perennial ryegrass infected with selected Epichloë fungal endophytes are highly desirable in certain pastures as the resulting mutualistic association has the capacity to confer agronomic benefits (such as invertebrate pest deterrence) largely due to fungal produced secondary metabolites (e.g., alkaloids). In this study, we investigated T2 segregating populations derived from two independent transformation events expressing diacylglycerol acyltransferase (DGAT) and cysteine oleosin (CO) genes designed to increase foliar lipid and biomass accumulation. These populations were either infected with Epichloë festucae var. lolii strain AR1 or Epichloë sp. LpTG-3 strain AR37 to examine relationships between the introduced trait and the endophytic association. Here we report on experiments designed to investigate if expression of the DGAT + CO trait in foliar tissues of perennial ryegrass could negatively impact the grass-endophyte association and vice versa. Both endophyte and plant characters were measured under controlled environment and field conditions. RESULTS: Expected relative increases in total fatty acids of 17-58% accrued as a result of DGAT + CO expression with no significant difference between the endophyte-infected and non-infected progeny. Hyphal growth in association with DGAT + CO expression appeared normal when compared to control plants in a growth chamber. There was no significant difference in mycelial biomass for both strains AR1 and AR37, however, Epichloë-derived alkaloid concentrations were significantly lower on some occasions in the DGAT + CO plants compared to the corresponding null-segregant progenies, although these remained within the reported range for bioactivity. CONCLUSIONS: These results suggest that the mutualistic association formed between perennial ryegrass and selected Epichloë strains does not influence expression of the host DGAT + CO technology, but that endophyte performance may be reduced under some circumstances. Further investigation will now be required to determine the preferred genetic backgrounds for introgression of the DGAT + CO trait in combination with selected endophyte strains, as grass host genetics is a major determinant to the success of the grass-endophyte association in this species.

Survey of the Endophytic Bacteria Inhabiting Wild Daucus Seed Using 16S rRNA Gene Amplicon Sequencing.

We report a preliminary survey of the endophytic bacterial microbiota of seed from wild carrot (Daucus carota) using 16S rRNA gene amplicon sequencing. Actinobacteria, Bacteroidetes, Firmicutes, and Proteobacteria were the most abundant phyla detected, while Bacillus, Massilia, Paenibacillus, Pantoea, Pseudomonas, Rhizobium, Sphingomonas, and Xanthomonas were the most abundant genera.

Mutualistic fungal endophytes in the Triticeae - survey and description.

Grasses of the tribe Triticeae were screened to determine the presence of mutualistic epichloae fungal endophytes. Over 1500 accessions, from more than 250 species, encompassing 22 genera within the Triticeae were screened using immunodetection and direct staining/microscopy techniques. Only two genera, Elymus and Hordeum, were identified as harbouring epichloae endophytes with accessions native to a range of countries including Canada, China, Iran, Kazakhstan, Kyrgyzstan, Mongolia, Russia and the USA. Genetic analysis based on simple sequence repeat data revealed that the majority of endophytes cluster according to geographical regions rather than to host species; many strains isolated from Hordeum grouped with those derived from Elymus, and amongst the Elymus-derived strains, there was no clear correspondence between clustering topology and host species. This is the first detailed survey demonstrating the genetic diversity of epichloae endophytes within the Triticeae and highlights the importance of germplasm centres for not only preserving the genetic diversity of plant species but also the beneficial microorganisms they may contain.