Heterosis of leaf and rhizosphere microbiomes in field‐grown maize

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 F 1 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 the 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 nonmicrobial 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.

Maize germplasm chronosequence shows crop breeding history impacts recruitment of the rhizosphere microbiome

“…We decided to focus solely on inbred lines as hybrid maize genotypes exhibit a high degree of heterosis [ 18 ] and typically represent a highly genetically diverse combination of different heterotic pedigrees. This is important, as recent research has now established that this hybrid vigor can have considerable impacts on the assembly of the rhizosphere microbiome [ 43 , 44 ]. Consequently, previous studies that included hybrids in their attempts to examine the effects of selection on maize through time unknowingly confounded heterosis and selection effects [ 45 , 46 ].…”

Rhizosphere microbiome: Functional compensatory assembly for plant fitness

“…In recent years, a reductionist approach to the synthetic community (SynCom) has been developed to study the specific mechanisms that drive community assembly and the interactions among different members in a gnotobiotic system [42] , [43] . For instance, the consistent differences between the maize phenotypes of inbred lines and hybrids and the composition of rhizosphere bacterial and fungal communities [44] have been further confirmed by inoculation with a simple community of seven bacterial strains [45] .This reductionist approach would allow global research to replicate experiments easily through two standardized pipelines: high-throughput bacterial cultivation and identification [46] , [47] and the establishment of plant growth systems [48] .…”

Water Stress and Disruption of Mycorrhizae Induce Parallel Shifts in Phyllosphere Microbiome Composition

“…Liu et al 2021), transplanting microbial communities from stressful conditions onto plants in the growth chamber did not improve disease resistance, so we cannot conclude whether stressinduced compositional shifts in phyllosphere microbiota are adaptive for the host plant. While it is always possible that other, unmeasured traits were improved by microbiome transplant, our results may reflect growing evidence that host selection is weaker in the phyllosphere than the rhizosphere (Wagner et al 2020).…”