Host- Epichloë endophyte compatibility plays a significant role in the estimate of genetic variances among cross progenies of tall fescue

Some evidence showed symbiosis with particular strains of Epichloë fungal endophyte eliminates self-incompatibility in host grasses which is ecologically important for seed and endophyte dispersal. This study was performed to investigate the effect of endophytic infection on genetic variances of forty full-sib families of tall fescue with their ten male parents, free from endophyte, and two female parents (75B and 75C) with both endophyte-infected (E+) and non-infected (E-) counterparts over two years. In addition, the effect of endophyte infection on selfing ratio and seed production via selfing was evaluated between endophyte-infected progenies and their non-infected counterparts. Genetic compatibility between the host and fungus was also evaluated by leaf sheath endophyte intensity (LSEI) and seed endophyte infection percentage (SEI%) indices. The results showed that genetic compatibility between the host and endophytic fungus was different between two infected female genotypes and their progenies. Compatibility parameters, leaf sheaths endophyte intensity, and seed endophyte infection rate were higher (2.78- and 1.2-fold, respectively) in 75B+ than in 75C+. Plant traits’ genetic variances were estimated higher among full-sib endophyte infected progenies of 75B+ compared to non-infected counterparts. On the contrary, the genetic variances of plant traits were lower in full-sib endophyte-infected progenies of 75C+ compared to E- counterparts. It seems that higher compatibility in host-endophyte interaction leads to a higher estimate of genetic variances after outcrossing. Based on the results, it is possible to develop new breeding programs with different purposes in tall fescue based on the genetic diversity created by endophyte infection.