Australian native Glycine clandestina seed microbiota hosts a more diverse bacterial community than the domesticated soybean Glycine max

Background: Plant microbiome composition has been demonstrated to change during the domestication of wild plants and it is suggested that this has resulted in loss of plant beneficial microbes. Recently, the seed microbiome of native plants was demonstrated to harbour a more diverse microbiota and shared a common core microbiome with modern cultivars. In this study the composition of the seed-associated bacteria of Glycine clandestina is compared to seed-associated bacteria of Glycine max (soybean).

Results: The seed microbiome of the native legume Glycine clandestina (crop wild relative; cwr) was more diverse than that of the domesticated Glycine max and was dominated by the bacterial class Gammaproteobacteria. Both the plant species (cwr vs domesticated) and individual seed accessions were identified as the main driver for this diversity and composition of the microbiota of all Glycine seed lots, with the effect of factor "plant species" exceeded that of "geographical location". A core microbiome was identified between the two Glycine species. A high percentage of the Glycine microbiome was unculturable [G. clandestina (80.8%) and G. max (75.5%)] with only bacteria of a high relative abundance being culturable under the conditions of this study.

Conclusion: Our results provided novel insights into the structure and diversity of the native Glycine clandestina seed microbiome and how it compares to that of the domesticated crop Glycine max. Beyond that, it also increased our knowledge of the key microbial taxa associated with the core Glycine spp. microbiome, both wild and domesticated. The investigation of this commonality and diversity is a valuable and essential tool in understanding the use of native Glycine spp. for the discovery of new microbes that would be of benefit to domesticated Glycine max cultivars or any other economically important crops. This study has isolated microbes from a crop wild relative that are now available for testing in G. max for beneficial phenotypes.