Genetic variation in host plant phenology affects microbial assemblages
at longitudinal niches of the seedling root after a short residence time
Abstract
The root tip of a plant is highly sensitive to environmental cues and
exerts sensory, chemical and movement responses and has even been
likened to an animal’s brain. Yet, the assemblage of microbes at the
root tip, the controls governing their diversity, the nature of their
recruitment to that particular niche, and their roles in plant
phenotypic function, remain poorly understood. This study investigated
longitudinal niche differentiation of the root-associated microbiome in
chickpeas ( Cicer arietinum L.) and its interactions with both
diverse soil types and host plants with genetic variation in phenology,
from the exterior to the interior of the root. Compared with late
flowering (LF) genotypes, endophyte microbiomes at the apical zone of
the early flowering (EF) host were characterised by greater diversity,
higher compositional similarity to the basal zone, and closely
inhabiting Rhizobacter and Methylotenera across soils.
Additionally, EF genotype secreted a specific composition of metabolites
from the apical zone, with more carboxylates (benzoic acid) and amino
acids (propionic acid) than the LF plant. Our findings demonstrate that
longitudinal differentiation within a seedling root is an essential
feature shaping the root microbiome and indicative of genetic variation
in phenology of host plants.