Rhizobiome Signature and Its Alteration Due to Watering in the Wild Plant Moringa oleifera

Abstract

Metagenomic approach was used to detect microbial gene abundance and relative abundance in the rhizosphere of Moringa oleifera and surrounding bulk soil and to detect the response of soil microbes to watering. Expectedly, the number and abundance of non-redundant genes were extremely higher in bacteria followed by archaea, eukaryota and viruses. Results demonstrated unexpected high abundance of some microbes (ex., endophyte genus Nocardioides) in the rhizosphere that are supposed to exist mainly in other rhizocompartments. We suggest this differential distribution of microbes is due to the specific pattern of host-microbe interaction. Other endosymbiont microbes, ex., fungi Mucoromycota and Ascomycota, were highly abundant in the bulk soil possibly because they are phytopathogens where plant exudates might inhibit their growth or force these fungi to approach reverse chemotaxis. Our data indicated high abundance of other symbiont microbes in the rhizosphere of M. oleifera at phylum (ex., Actinobacteria) and genus (ex., Streptomyces) levels. Watering experiment indicated that phylum Actinobacteria and the descending genus Streptomyces are among the highest. Rhizobiome of M. oleifera seems to harbor a wealth of new species of the genus Streptomyces that are required to be deciphered for function in order to be eventually utilized in pharmaceutical and agricultural applications.