Heterosis of leaf and rhizosphere microbiomes in field-grown maize

Authors: WAGNER, M - University Of Kansas; ROBERTS, J - Kansas Geological Survey; Balint-Kurti, Peter; Holland, Jim - Jim

Submitted to: New Phytologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/1/2020
Publication Date: 8/1/2020
Citation: Wagner, M.R., Roberts, J.H., Balint Kurti, P.J., Holland, J.B. 2020. Heterosis of leaf and rhizosphere microbiomes in field-grown maize. New Phytologist. https://doi.org/10.1111/nph.16730.
DOI: https://doi.org/10.1111/nph.16730

Interpretive Summary: Plants live in close association with microbial organisms, bacteria and fungi. Microbes live on leaf and root surfaces and may also live inside of plant tissues; the collective set of such microbes associated with a plant is called its microbiome. Whereas some microbes cause disease, most microbes in the microbiome have no clear effect on the host plant, although there is evidence that some microbial associations are beneficial to the host plants. In this study, we characterized the microbiomes associated with several diverse maize inbred lines and the hybrids created by crossing the inbred lines. We found patterns of microbiomes that differed significantly between inbreds and hybrids in general, and we also found that the microbiomes of many hybrids were distinct than the average of the parental microbiomes. Therefore, there is a hybrid effect on microbiomes. Future research is needed to determine the extent to which the host plant hybrid effect on growth and development changes the microbiome, versus the possibility that hybridization effects on the microbiome cause some of the hybrid vigor of corn.

Technical Abstract: Macroorganisms’ genotypes shape their phenotypes, which in turn shape the habitat available to potential microbial symbionts. This influence of host genotype on microbiome composition has been demonstrated in many systems; however, most previous studies have either compared unrelated genotypes or delved into molecular mechanisms. As a result, it is currently unclear whether the heritability of host-associated microbiomes follows similar patterns to the heritability of other complex traits. We take a new approach to this question by comparing the microbiomes of diverse maize inbred lines and their F1 hybrid offspring, which we quantified in both rhizosphere and leaves of field-grown plants using 16S-v4 and ITS1 amplicon sequencing. We show that inbred lines and hybrids differ consistently in composition of bacterial and fungal rhizosphere communities, as well as leaf-associated fungal communities. A wide range of microbiome features display heterosis within individual crosses, consistent with patterns for non-microbial maize phenotypes. For leaf microbiomes, these results were supported by the observation that broad-sense heritability in hybrids was substantially higher than narrow-sense heritability. Our results support our hypothesis that at least some heterotic host traits affect microbiome composition in maize.