Investigating the effect of seed-banking on Australian-native seed microbiome composition and function

Native species revegetaHon plays a central role in addressing biodiversity decline and restoring functional ecosystems. Native seeds held in seed banks are a vital resource underpinning these efforts. However, germination, seedling establishment and survival rates from banked seed can be poor. In agricultural species, seeds carry microorganisms that can assist in germination, nutrient acquisition, growth, and stress protection. The composition and functional potential of microbes associated with Australian native plants remains largely unknown. Consequently, it is unknown whether seed banking practices appreciably affect native seed microbiomes and whether this may have flow on effects for revegetation success. This thesis investigated differences in the seed surface microbiome of the Australian native Acacia ulicifolia (Salisb.) Court. in seeds obtained from seedbank facilities and natural populations, using both culture-dependent and independent approaches. Stored seed samples showed significantly lower bacterial diversity and abundance than seeds collected from natural populations and also had fewer culturable bacteria displaying putative plant growth promoting traits. Additionally, a previously undescribed rhizobia (1174-901-12) was identified as a common feature in natural seed microbiomes, but was not recovered from stored seed. Overall, these results suggest that simplification of the seed epiphyte microbiome may take place during storage and warrants further investigation.