Cicer reticulatum and C. echinospermum Microbiomes: Exploration of Plant-Microbe Interractions in Wild Chickpea Populations

Plants depend on soil microorganisms for a range of services, including nutrient acquisition. Most crops are cultivated in areas distant from their center of origin. However, it is uncertain whether microbes from the center of origin were “transplanted” as the crops moved to new areas, or whether and to what extent native microbes in new areas of cultivation yield surrogate functionalities. Similarly, whether microbial communities were co-domesticated with crops and selected for crop-relevant adaptations is unknown. Answering such questions requires that we first understand the plant microbiome in native communities of crop wild progenitors.

Chickpea was domesticated in south-eastern Turkey ~10KYA. We have systematically collected and characterized genomic variation in the crop wild relatives, as well as soil and climatic factors at the crop’s center of origin. In parallel, we sampled microbial DNA from soil close to and associated with different plant compartments. Here we report 16S analysis from ~800 samples among 21 sites containing 9 populations of wild chickpea.

Microbial communities demonstrated a selection gradient moving from the soil toward the plant tissues, with compartment-specific characteristic changes in taxa and significant decreases in alpha diversity. A combination of in situ sampling and reciprocal soil transplant experiments was used to determine the relative importance of soil vs plant genotype in structuring microbial communities. We determined, for example, that symbiotic association with nitrogen fixing symbionts was soil-type but not host genotype dependent. This work provides a foundation for understanding the degree to which microbial communities transitioned from wild to cultivated systems.