Analysis of Bacterial Communities in White Clover Seeds via High-Throughput Sequencing of 16S rRNA Gene

Abstract

White clover widely cultivated in China is one of the most important perennial leguminous forages in temperate and subtropical regions. There is a large quantity of white clover seeds imported into China each year for demands of high-quality grass seeds. Seedborne diseases may cause significant economic losses. DNA sequencing technologies allow for the direct estimation of microbial community diversity, avoiding culture-based biases. Therefore, we used 16S rRNA gene sequencing to investigate the bacterial communities in white clover seeds collected from four different countries. The results showed that a total of 484,715 clean reads were obtained for further subsequent analysis. In total, 341, 340, 382, and 297 operational taxonomic units were obtained at 3% distance cutoff in DB, MB, TB, and XB samples, respectively. The richness indexes revealed that TB sample from Argentina had the highest bacterial richness in four samples. Our results demonstrated that Proteobacteria was the dominant phyla in MB, TB, and XB; however, Bacteroidetes was the dominant phyla in DB. The dominant genus of DB was Prevotella (11.9%), while Sphingomonas was the major genus of MB (46.9%), TB (55.08%), and XB (47.2%) samples. These results provide useful information for seedborne diseases and transmission of bacteria from seed to seedling.