IANNONE Leopoldo Javier
congresos y reuniones científicas
POTENTIAL PROTECTIVE TOXICITY TO HERBIVORES CONFERRED TO GRASSES BY ASEXUAL EPICHLOË SPECIES FROM ARGENTINA.
MC CARGO, P.D.; OLIVERO, L.M; FLOREA S.,; NOVAS M.V.,; SCHARDL C.L; IANNONE L.J.
Congreso; 9TH INTERNATIONAL HERBAGE SEED CONFERENCE; 2018
International Herbage Seed Group
Epichloë species are fungal systemic symbionts of cool-season grasses (Poaceae subfamily Pooideae) that can confer resistance to environmental stress, pests and diseases to their hosts. These characteristics have made endophytes a tool for grass forage breeding. Most of these symbionts can produce alkaloids that provide protection from herbivory, which can be insect deterrents (e.g. lolines and peramine) or toxic to livestock (e.g. the indole-diterpene lolitrem-B and the ergot alkaloid ergovaline). In Argentina only asexual Epichloë species have been found. We studied the diversity in alkaloid gene profiles of Epichloë isolates from 18 native hosts from Argentina. We screened for presence of alkaloid biosynthesis genes (perA, lolC, dmaW and idtG, K, B, Q, F, E) and assessed the potential alkaloid production of the endophyte, which is considered agronomically important for selection and future development of grass cultivars. Ten genotypes differing in the alkaloids gene profiles (presence/absence) were revealed across the eight lineages identified with the calM phylogenies. The ten genotypes reduced to seven different predicted chemotypes. All lineages are predicted to produce peramine, but only E. cabralii, E. pampeana, lineage A and some isolates of lineage C would likely synthesize lolines. Lineage B is predicted to synthesize the ergot alkaloid intermediate compound chanoclavine-I that is non-toxic to cattle. The genotypes with indole-diterpene biosynthesis genes showed greater genetic variation. E. typhina ssp. poae var. aonikenkana and lineages B, C, D, would likely produce paxiline and terpendole-I. Two different indole-diterpene chemotypes were predicted within E. tembladerae, some isolates would likely be terpendole-C producers while others would produce paspaline. According to the predicted alkaloid chemotypes, Argentinean endophytes have the potential to produce alkaloids with anti-insect activity but are likely safe for livestock, so they could be an adequate resource to improve the resistance of forage grasses to biotic stresses.