Effects of grafting on the structure and function of coffee rhizosphere microbiome

The obstacle of continuous coffee cultivation is one of the main bottlenecks limiting the development of the coffee industry. The heterologous double root grafting method is one of the effective solutions to alleviate coffee continuous cropping obstacles and reduce soil borne diseases in coffee. But its specific regulatory mechanism is not yet clear. Therefore, a field experiment was established to clarify the effects of heterologous double root grafting methods on the root exudates and soil microbial diversity, structure, and function of Robista and Liberian coffee, and to reveal the mechanism of enhancing the rhizosphere immunity of Robista coffee by grafting Liberian coffee. The results showed significant differences in root exudates, rhizosphere microbial structure and function between Robusta coffee and Liberian coffee. Although Liberian coffee has lower diversity of rhizosphere microbial communities and relatively higher abundance of potential pathogenic bacteria, its resistance to potential diseases is stronger. Connecting to the roots of Liberian coffee significantly enhances the secretion of resistance substances in Robusta coffee roots, increases the relative abundance of potential beneficial bacteria, and reduces the relative abundance of potential pathogenic fungi, which helps to enhance the rhizosphere immunity of Robusta coffee roots to soil borne diseases. The results indicated that by connecting to the roots of Liberian coffee, it can obtain stronger resistant roots and enhance its own rhizosphere immunity, alleviating continuous cropping obstacles in Robusta coffee plants. The results of this study provide important basis for a deeper understanding of the regulatory mechanism of grafting on coffee rhizosphere microorganisms and for optimizing coffee planting techniques.