Influence of Epichloë coenophiala, a seed-borne endophyte, on the micropropagation of tall fescue

Abstract

Improving micropropagation success rate is important since this technique allows the development of other biotechnological tools, such as genetic transformation, in vitro polyploidization, or endophyte inoculation. This is particularly relevant for grasses, as they are traditionally considered recalcitrant to plant tissue culture. Grasses of the subfamily Pooideae establish mutualistic associations with grass endophyte fungi of the genus Epichloë. These associations are specific, as each host species is associated with one or few Epichloë species. Lolium arundinaceum (Schreb.) Darbysh. is a perennial C3 species, native to Europe, which has become an important cool season forage crop worldwide. This grass usually establishes beneficial symbioses with E. coenophiala, but these benefits depend on both plant and fungal genetics and environmental conditions. Micropropagation protocols have been published for L. arundinaceum, but the influence of Epichloë endophytes was never examined. The aim of this manuscript was to study the effect of E. coenophiala on different micropropagation stages of L. arundinaceum and growth of the regenerated plantlets. Association with E. coenophiala (E+) increased callus induction, enhanced their proliferation, and increased shoot regeneration in L. arundinaceum. However, the biomass of plantlets regenerated from E+ seeds was lower than from non-associated seeds, both in vitro and ex vitro, and the in vitro multiplication rate also decreased. Contrary to other endophyte Epichloë-host associations with Lolium multiflorum and Bromus auleticus, the association with E. coenophiala did not improve tall fescue micropropagation. We can conclude that the effects of Epichloë endophytes on micropropagation and growth of their host differ for each endophyte-host association.