Abstract:

Endophytic bacteria are essential to the growth and metabolism of their host plants. To better understand the community structure and diversity of endophytic bacteria on plants, we isolated 94 strains of endophytic bacteria from the roots, stems and leaves of Dongxiang wild rice (Oryza rufipogon). Subsequent 16S rRNA sequence alignments and phylogenetic analyses revealed that the 94 strains could be categorized into 17 genera of 14 families in 3 phyla (Proteobacteria, Actinobacteria, and Firmicutes).Bacillus and Microbacterium, accounting for 27.7% and 20.2% of the diversity, respectively, were the two most dominant genera. The distribution and diversity of endophytic bacteria differed across different tissues of Dongxiang wild rice: the roots contained the most endophytic bacteria strains (n = 34, 36.2%), followed by leaves (n = 32, 34.0%), and stems (n = 28, 29.8%). Shannon-Wiener diversity index (H′ = 2.52), Simpson dominance index (D = 0.88) and Pielou evenness index (E = 0.72) were higher in the roots than in the stems or leaves. Meanwhile, the Jaccard similarity index between roots and stems (C = 0.29) was lower than that between roots and leaves (C = 0.47), or that between stems and leaves (C = 0.45). Our efforts to uncover the diversity of endophytic bacteria in Dongxiang wild rice confirms that roots contain the most diverse strains but that the composition of endophytes varies across tissues.

Key words: Oryza rufipogon, endophytes, classification, phylogeny, composition analysis