Profiling the Lolium perenne Microbiome: From Seed to Seed

Lolium perenne (perennial ryegrass) is a common temperate pasture grass species and is favored by dairy farmers. Commercially, the known association with the mutualistic endophytic fungus Epichloë festucae subsp. lolii is used to enhance insect resistance of host plants. Knowledge of other members of the microbiome and their functions are limited. Sequencing of the V4 region of the 16S ribosomal RNA gene was used to examine the bacterial microbiome of perennial ryegrass (Alto) seed (generation 1 [G1]), subsequent mature plants grown in soil and sand, and seed (generation 2 [G2]) from crosses of these mature plants. The G1 microbiome was dominated by the class Gammaproteobacteria. The mature plant microbiomes were far more diverse, comprising up to 37 classes inclusive of Gammaproteobacteria. Different growth media yielded different microbiome profiles in mature plants. The G2 microbiome, similar to the G1 microbiome, was dominated by Gammaproteobacteria as the primary constituent, with additional supplementation from class Bacilli. This suggests the continuation of a core microbiome which persists from seed through plant maturation to seed. This study sheds new light on the hereditability of perennial ryegrass bacterial microbiomes and has identified some operational taxonomic units of potential commercial significance due to their seed transmissibility, and their roles are currently being explored.