Endophytic bacterial communities in in vitro shoot cultures derived from embryonic tissue of hybrid walnut (Juglans × intermedia)

Abstract

A detailed picture of the endophytic bacterial community structure on phylum and genus level in in vitro shoot cultures of sixteen Juglans genotypes including Jug-lans regia, Juglans nigra and mainly Juglans hybrids was generated by using culture-dependent and culture-inde- pendent methods. A total of eight endophytic bacterial strains with a high identity score (97–100%) were isolated from tissue culture shoot material derived from embry- onic tissue of Juglans hybrids by the culture-dependent approach. By sequence comparison of a 16S rRNA fragment to the NCBI database, they were identified as Acinetobacter, Brevundimonas, Moraxella, Pseudomonas, and Roseomonas species. The culture-independent approach involved Illumina MiSeq 16S rRNA amplicon sequencing. Five different phyla (Actinobacteria, Bacteroidetes, Cyanobacteria, Firmicutes, and Proteobacteria) were analyzed in more detail. The phylum Proteobacteria including genera such asrevundimonas spp., Acinetobacter spp. and Moraxella spp. showed the highest relative abundance of endophytic bacteria. Thus, the results of the sequencing