Seed microbiomes of pasture species and their role in plant protection and plant growth

Dr Ross Mann1, Dr Jatinder Kaur1, Dr Dilani  De Silva1, Dr Piyumi Ekanayake1, Mr Desmond Auer1, Miss Holly Hone1, Mr Tongda Li1,2, Mr Ian Tannenbaum1,2, Dr Tim Sawbridge1,2, Prof German Spangenberg1,2

1Agriculture Victoria, AgriBio, Centre for AgriBioscience, Coburg, Australia, 2School of Applied Systems Biology, La Trobe University, Bundoora, Australia

Plant seeds harbour microbes that assist in critical stages of a plant’s life, including germination and early seedling development.  The seed microbiome is thought to play an integral role in the protection and growth of the host plant during these life stages.  In the case of pasture grasses the seed transmitted, mutualistic fungal endophyte Epichloe spp. assists the host in protection against biotic and abiotic stress. However, the broader seed microbiome of pasture species is largely unknown.

The seed microbiome of tall fescue was profiled across global accessions to establish a core seed microbiome, while the seed microbiome of perennial ryegrass was assessed to determine the effect of the resident fungal endophyte on the seed microbiome and the seed transmissibility of the seed microbiome.  The microbiome of perennial ryegrass was isolated and strains were assessed via in vitro, in planta and in silico analyses to predict their function.  Key isolates were shown to possess a range of putative functions including bioprotection against common Poaceae pathogens and biostimulation via nitrogen and phosphorous acquisition.        

This study sheds new light on pasture grass microbiomes and has identified some bacteria of potential commercial significance due to their seed transmissibility and likely importance in seed germination, early seedling vigour, and protection of the host against pests and disease.