Epichloë occultans enhances micropropagation efficiency in Lolium multiflorum

Abstract

Italian ryegrass (Lolium multiflorum) is an annual grass considered as one of the most important temperate forage grasses in the world. However, it is recalcitrant to plant tissue culture techniques hindering its genetic manipulation. Epichloë occultans is an endophytic fungus associated with L. multiflorum. This symbiosis causes improvements in physiological and ecological traits of the host plants. The objective of this work was to study the effect of E. occultans on L. multiflorum micropropagation. We compared the response of endophyte-infected (E+) and endophyte-free (E−) seeds in different micropropagation stages. The E+ seeds were more successful than E− seeds in in vitro germination (83 ± 5 vs. 63 ± 6%), callus induction (78 ± 5 vs. 57 ± 6%), callus proliferation (average diameter of 21.5 ± 1.3 mm in two subcultures vs 17.3 ± 0.8 mm in three subcultures) and plant regeneration from callus (83 ± 7 vs. 30 ± 8%). These results indicate that E. occultans enhances significantly L. multiflorum micropropagation. The use of endophyte-infected (E+) seeds can be a solution to make this grass more amenable to different biotechnological tools, such as the genetic transformation.