## 1 Introduction  
The rhizosphere microbiome, which includes the totality of microorganisms, their genomes, and interactions in the rhizosphere has been the focus of several studies in recent times. The microorganisms that inhabit the rhizosphere have numerous beneficial functions, which range from nutrient acquisition, stress tolerance, and protection against pathogens [1]. Soil is not just a single environment but consists of many environments that have distinct microbial communities. Distinct soil environments may range from a few micrometers to millimeters apart, and their microbial abundances, rate of microbial activity, abiotic characteristics, and composition of the microbial community may differ [2]. Soil microorganisms have the largest reservoir of biodiversity [3], and these microorganisms perform different activities, although these biological activities mostly take place in the rhizosphere, where there is communication between the plant roots and the microorganisms. Plants modify the rhizosphere directly through rhizedgeposition and root exudates, leading to changes in the composition and function of the rhizosphere microbiome [3]. Plant species growing in particular environments can recruit significantly different microbial communities in both the endosphere and rhizosphere [4]. Plant-associated microorganisms affect the fitness and physiology of the host plant by altering nutrient availability to the plant, thereby improving plant resistance to biotic and abiotic stressors [5]. Microbial community activity, especially in the rhizosphere, is often connected to variation in the physical or chemical properties of the soil such as soil texture, pH, or changes in land use [6]. Biotic and abiotic factors determine the structure and composition of the soil microbiome. Thus, explaining the strong relationship between plant and microorganism using soil type, soil age, soil pH, and mineralogy [7]. In addition, plant location and plant species are determinants to which microorganisms can grow and thrive in the rhizosphere [8; 9]. The microbiome can be explored because it has been postulated to be one of the key components of technological innovation to improve plant health and production [6]. Bacteria being the most dominant domain in the rhizosphere possess plant-growth-promoting-traits. Therefore, they have the potential of being used as a viable tool for sustainable agriculture [10]. Reports have shown that the genes that have been identified to have plant-beneficial attributes range from genes that confer plant-beneficial properties such as _phl_ (phloroglucinol synthesis) [11] or _nif_ (nitrogen fixation) [12] to genes involved in numerous indirect functions or secondary plant-beneficial ones like pqq (pyrroloquinoline quinone synthesis) [13]. Other plant-beneficial function-contributing genes that have been identified to enhance the growth of plants in the rhizosphere are ACC deaminase, auxin synthesis, hydrogen cyanide synthesis, phosphate solubilization, and 2,4-diacetylphloroglucinol synthesis genes [13; 14]. Understanding the rhizosphere microbiome through the means of taxonomic, genomic, and functional components is important for sustainable crop production [15]. There has been a good level of success toward the characterization of the rhizosphere microbiome in some crop plants such as rice, soybean, corn, barley, and wheat by exploring the structure, functional genes, and factors that drive the microbiome assemblages [15]. We hypothesized that the rhizosphere microbiome would be more diverse than the bulk soil because of the activities that take place there and because the soil physicochemical parameters affect the microbial diversity and community structure. We also hypothesized that genes beneficial to plant growth would be higher in the rhizosphere than in the bulk soil due to plant selectivity.