Effect of continuous cropping of konjac (Amorphophallus konjac) on soil bacterial communities as evaluated by Illumina high-throughput sequencing

Abstract

ABSTRACT Illumina high-throughput sequencing was used to explore the diversity and composition of the soil and root endosphere bacterial communities in three replanted konjac sites in 1-, 3-, and 5-year cropping systems. Continuous cropping of konjac caused a substantial decrease in soil pH and the activities of soil sucrase, urease, catalase, and alkaline phosphatase, and led to a remarkable and persistent decrease in the soil and root endosphere bacterial species abundance and alpha-diversity. Among the nine dominant bacterial phyla, Proteobacteria and Actinobacteria had the highest relative abundance, with averages of 61.3% and 11.2%, respectively. Several potentially beneficial genera, including Acinetobacter, Arthrobacter, and Pseudomonas, were less abundant in soil (84.6%, 82.7%, and 83.3%) and root (98.6%, 71.4%, and 98.1%) samples under 5 years of continuous cropping compared with those under 1-year cropping. Conversely, the potentially harmful genus Haliangium exhibited higher relative abundance in 5-year soil and root samples than in 1-year samples. Continuous cropping altered the bacterial community composition in the soil and root endosphere of konjac by influencing soil variables, leading to a reduction in the alpha-diversity of bacteria and the relative abundance of potentially beneficial bacteria, which in turn resulted in konjac poor growth in the continuous cropping system.