Résumé
A wide range of plant lines has been propagated by farmers during crop
selection and dissemination, but consequences of this crop diversification
on plant-microbe interactions have been neglected. Our hypothesis was that
crop evolutionary history shaped the way the resulting lines interact with
soil bacteria in their rhizospheres. Here, the significance of maize
diversification as a factor influencing selection of soil bacteria by
seedling roots was assessed by comparing rhizobacterial community
composition of inbred lines representing the five main genetic groups of
maize, cultivated in a same European soil. Rhizobacterial community
composition of 21-day-old seedlings was analyzed using a 16S rRNA
taxonomic microarray targeting 19 bacterial phyla. Rhizobacterial
community composition of inbred lines depended on the maize genetic group.
Differences were largely due to the prevalence of certain
Betaproteobacteria and especially Burkholderia, as confirmed by
quantitative PCR and cloning/sequencing. However, these differences in
bacterial root colonization did not correlate with plant microsatellite
genetic distances between maize genetic groups or individual lines.
Therefore, the genetic structure of maize that arose during crop
diversification (resulting in five main groups), but not the extent of
maize diversification itself (as determined by maize genetic distances),
was a significant factor shaping rhizobacterial community composition of
seedlings.