Metagenomics Assessment of Soil Fertilization on the Chemotaxis and Disease Suppressive Genes Abundance in the Maize Rhizosphere.

Matthew Enebe,Olubukola Babalola

doi:10.3390/genes12040535

Abstract

Soil fertility is a function of the level of organic and inorganic substances present in the soil, and it influences the activities of soil-borne microbes, plant growth performance and a host of other beneficial ecological functions. In this metagenomics study, we evaluated the response of maize microbial functional gene diversity involved in chemotaxis, antibiotics, siderophores, and antifungals producing genes within the rhizosphere of maize plants under compost, inorganic fertilizer, and unfertilized conditions. The results show that fertilization treatments at higher compost manure and lower inorganic fertilizer doses as well as maize plants itself in the unfertilized soil through rhizosphere effects share similar influences on the abundance of chemotaxis, siderophores, antifungal, and antibiotics synthesizing genes present in the samples, while higher doses of inorganic fertilizer and lower compost manure treatments significantly repress these genes. The implication is for a disease suppressive soil to be achieved, soil fertilization with high doses of compost manure fertilizer treatments as well as lower inorganic fertilizer should be used to enrich soil fertility and boost the abundance of chemotaxis and disease suppressive genes. Maize crops also should be planted sole or intercropped with other crops to enhance the rhizosphere effect of these plants in promoting the expression and abundance of these beneficial genes in the soil.

Highlights

The movement of microbes from one point in the environment to another as a result of potential differences in nutrients or proper chemical gradients is termed chemotaxis
The microbial sequenced genomes present at the maize rhizosphere have an abundant of Proteobacteria and Actinobacteria which was dominant in Cp8, Cn0, and N1 samples
We evaluated the response of maize microbial functional gene diversity involved in chemotaxis, antibiotics, siderophores, and antifungals production within the rhizosphere of maize plants under inorganic compost fertilizer and unfertilized conditions

Summary

Introduction

The movement of microbes from one point in the environment to another as a result of potential differences in nutrients or proper chemical gradients is termed chemotaxis. Chemotaxis has many physiological roles, such as improving access to growth nutrients as well as in the initiation of infection. This movement is ATP (energy) dependent for efficient flagella and other locomotory structures of the microbes in responding to the chemical gradients stimuli. The priming of the chemosensory pathways by the signaling molecules facilitates chemotaxis, and this begins when the chemical molecules bind to the receptors, which form complexes with cheA (a histidine kinase) and cheW (an adaptor protein). The primed cheA will result in autophosphorylation on histidine residue with a corresponding trans-phosphorylation of cheY (a primary response regulator) which binds to the flagella motor to initiate chemotaxis movement [1,2]. Bacteria perform energy taxis in response to migrating to suitable environments that support their metabolic activities [4], as observed in the rhizosphere of organic manure fertilized maize plants

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