Lolium perenne (perennial ryegrass) is a common temperate pasture grass species and is favoured 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 rRNA gene was used to examine the bacterial microbiome of perennial ryegrass (cv. Alto) seeds (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 Gammaproteobacteria. The mature plant microbiomes were far more diverse, comprising of up to 37 Classes inclusive of Gammaproteobacteria. Different growth media yielded different microbiome profiles in mature plants. The G2 microbiome, as G1, was dominated by Gammaproteobacteria with additional supplementation of 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 microbiomes and has identified some OTUs of potential commercial significance due to their seed transmissibility and their roles are currently being explored.

Climate change is predicted to increase the incidence and severity of drought conditions, posing a significant challenge for agriculture globally. Plant microbiomes have been demonstrated to aid crop species in the mitigation of drought stress. The study investigated the differences between the seed microbiomes of drought tolerant and drought susceptible wheat lines. Furthermore, it highlighted and quantified the degree of drought tolerance conferred by specific microbes isolated from drought tolerant wheat seed microbiomes. Metagenomic and culture-based methods were used to profile and characterise the seed microbiome composition of drought tolerant and drought susceptible wheat lines under rainfed and drought conditions. Isolates from certain genera were enriched by drought tolerant wheat lines when placed under drought stress. Wheat inoculated with isolates from these targeted genera, such as Curtobacterium flaccumfaciens (Cf D3-25) and Arthrobacter sp. (Ar sp. D4-14) demonstrated the ability to promote growth under drought conditions. This study indicates seed microbiomes from genetically distinct wheat lines enrich for beneficial bacteria in ways that are both line-specific and responsive to environmental stress. As such, seed from stress-phenotyped lines represent an invaluable resource for the identification of beneficial microbes with plant growth promoting activity that could improve commercial crop production.