AUTHOR=Gebauer Lucie , Bouffaud Marie-Lara , Ganther Minh , Yim Bunlong , Vetterlein Doris , Smalla Kornelia , Buscot François , Heintz-Buschart Anna , Tarkka Mika T. 

TITLE=Soil Texture, Sampling Depth and Root Hairs Shape the Structure of ACC Deaminase Bacterial Community Composition in Maize Rhizosphere

JOURNAL=Frontiers in Microbiology

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2021.616828

DOI=10.3389/fmicb.2021.616828

ISSN=1664-302X

ABSTRACT=<p>Preservation of the phytostimulatory functions of plant growth-promoting bacteria relies on the adaptation of their community to the rhizosphere environment. Here, an amplicon sequencing approach was implemented to specifically target microorganisms with 1-aminocyclopropane-1-carboxylate deaminase activity, carrying the <italic>acdS</italic> gene. We stated the hypothesis that the relative phylogenetic distribution of <italic>acdS</italic> carrying microorganisms is affected by the presence or absence of root hairs, soil type, and depth. To this end, a standardized soil column experiment was conducted with maize wild type and root hair defective <italic>rth3</italic> mutant in the substrates loam and sand, and harvest was implemented from three depths. Most <italic>acdS</italic> sequences (99%) were affiliated to Actinobacteria and Proteobacteria, and the strongest influence on the relative abundances of sequences were exerted by the substrate. <italic>Variovorax, Acidovorax</italic>, and <italic>Ralstonia</italic> sequences dominated in loam, whereas <italic>Streptomyces</italic> and <italic>Agromyces</italic> were more abundant in sand. Soil depth caused strong variations in <italic>acdS</italic> sequence distribution, with differential levels in the relative abundances of <italic>acdS</italic> sequences affiliated to <italic>Tetrasphaera, Amycolatopsis</italic>, and <italic>Streptomyces</italic> in loam, but <italic>Burkholderia</italic>, <italic>Paraburkholderia</italic>, and <italic>Variovorax</italic> in sand. Maize genotype influenced the distribution of <italic>acdS</italic> sequences mainly in loam and only in the uppermost depth. Variovorax <italic>acdS</italic> sequences were more abundant in WT, but <italic>Streptomyces, Microbacterium</italic>, and <italic>Modestobacter</italic> in <italic>rth3</italic> rhizosphere. Substrate and soil depth were strong and plant genotype a further significant single and interacting drivers of <italic>acdS</italic> carrying microbial community composition in the rhizosphere of maize. This suggests that maize rhizosphere <italic>acdS</italic> carrying bacterial community establishes according to the environmental constraints, and that root hairs possess a minor but significant impact on <italic>acdS</italic> carrying bacterial populations.</p>