Identification of biomarkers associated with the survival of selected Epichloë endophytes while in seed storage
DOI:
https://doi.org/10.33584/rps.18.2025.3857Abstract
Epichloë is a genus of fungal endophytes that form symbiotic associations with cool season grasses in the sub-family Pooideae. In New Zealand, selected strains of asexual Epichloë endophytes have been developed into commercial products for pasture persistence and wild-life deterrence where they confer bioprotective traits to their host grasses. As asexual Epichloë species are exclusively vertically transmitted, their survival in seed is critical for their dissemination to progeny plants. Endophyte survival declines at a much faster rate than seed viability, however the mechanism responsible for this decline is unknown. This study investigated the effects of seed aging on mycelial biomass and selected metabolite concentrations in Epichloë-infected seed of perennial ryegrass (Lolium perenne) with the main objective to identify key metabolites that play a significant role in the viability of endophyte in seed during storage. Fifty-eight seed lines, comprised of three cultivars of perennial ryegrass associated with two economically important endophyte strains (AR1 and AR37), were subjected to an accelerated ageing regime designed to mimic the physical deterioration processes that would occur during natural seed aging. Selected amino acids, neutral sugars, sugar alcohols, phytohormones and Epichloë-derived secondary metabolites were then analysed and their concentrations examined for effect of seed aging, cultivar, and endophyte strain. As predicted, accelerated ageing had little to no effect on the seed germination rate of the selected ryegrass cultivars but negatively impacted the frequency of endophyte viability within seed. Proline and xylose gave the greatest fold changes in concentration across all grass cultivars after seed aging but were not correlated to endophyte infection frequencies and therefore not suitable as biomarkers. Ribitol, a sugar alcohol, exhibited concentration fold changes that correlated with endophyte viability and therefore has potential as a biomarker to trace the viability of endophytes in perennial ryegrass seed during storage.
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