Exploring eco-evolutionary and temporal patterns of arbuscular mycorrhizal fungal communities colonizing Sorghum bicolor across sites of contrasting land use history and climate

Societal Impact StatementSorghum bicolor is a globally important crop, having endpoint uses ranging from human food to animal feed to biofuel production. Sorghum is stress-tolerant and can be grown on marginal land that may be otherwise unsuitable for large-scale food production. Sorghum is therefore a promising candidate for agricultural strategies focused on maximizing production on these marginal lands through beneficial interactions with arbuscular mycorrhizal fungi and other microbes. This study investigates how sorghum genotypes and their interactions with the environment can be leveraged to foster particular AMF assemblages which can be investigated further for their effect on the host plant. Arbuscular mycorrhizal fungal (AMF) symbiosis can influence crop production, but can be variable across environmental conditions, host-partner complementarity and temporal dynamics. Understanding how these factors interact to shape AMF community assembly allows for the selection of crop genotypes that may maximally utilize AMF associations in agricultural systems. We assessed the development of AMF communities colonizing the roots of eight genetically diverse genotypes of Sorghum bicolor across a growing season. We used two field sites with contrasting environments and management histories. Sorghum cultivated in Arizona (AZ) contained low diversity AMF communities, while in Georgia (GA) sorghum harbored more diverse and evenly distributed AMF communities. We observed evidence of host-filtering of AMF communities, though with genotypes displaying more distinct associations in GA than AZ. AZ showed rapid shifts from early Funneliformis mosseae dominance to dominance by either Entrophospora etunicata or Diversispora aurantia. In GA, such drastic abundance shifts were not observed. Instead, consistent temporal turnover was associated more with higher level family abundance patterns driven by the combination of minor variations in multiple low-abundance taxa. Our findings demonstrate that there is potential for leveraging intra-species genetic variation in AMF community assembly as an extended plant phenotype.