Bacteriome from Pinus arizonica and P. durangensis: Diversity, Comparison of Assemblages, and Overlapping Degree with the Gut Bacterial Community of a Bark Beetle That Kills Pines

Abstract

Symbioses between plants and microorganims have been fundamental in the evolution of both groups. The endophytic bacteria associated with conifers have been poorly studied in terms of diversity, ecology, and function. Coniferous trees of the genera Larix, Pseudotsugae, Picea and mainly Pinus, are hosts of many insects, including bark beetles and especially the Dendroctonus species. These insects colonize and kill these trees during their life cycle. Several bacteria detected in the gut and cuticle of these insects have been identified as endophytes in conifers. In this study, we characterized and compared the endophytic bacterial diversity in roots, phloem and bark of non-attacked saplings of Pinus arizonica and P. durangensis using 16S rRNA gene pyrosequencing. In addition, we evaluated the degree of taxonomic relatedness, and the association of metabolic function profiles of communities of endophytic bacteria and previously reported gut bacterial communities of D. rhizophagus; a specialized bark beetle that colonizes and kills saplings of these pine species. Our results showed that both pine species share a similar endophytic community. A total of seven bacterial phyla, 14 classes, 26 orders, 43 families, and 51 genera were identified. Enterobacteriaceae was the most abundant family across all samples, followed by Acetobacteraceae and Acidobacteriaceae, which agree with previous studies performed in other pines and conifers. Endophytic communities and that of the insect gut were significantly different, however, the taxonomic relatedness of certain bacterial genera of pines and insect assemblages suggested that some bacteria from pine tissues might be the same as those in the insect gut. Lastly, the metabolic profile using PICRUSt showed there to be a positive association between communities of both pines and insect gut. This study represents the baseline into the knowledge of the endophytic bacterial communities of two of the major hosts affected by D. rhizophagus.

Agricultural and Other Biotechnological Applications Resulting from Trophic Plant-Endophyte Interactions

“…The sequencing proceeds through a cycle of washing and flooding fragments with known nucleotides in sequential order. As nucleotides incorporate into the growing DNA strand, they are digitally recorded as a sequence [22][23][24]. Three basic platforms can be distinguished in NGS: Roche 454-pyrosequencing, Ion Torrent, and Illumina sequencing.…”

“…A list of the most recent metagenomic studies [11][12][13][14][15][16][17]23,24,[32][33][34][35][36][37][38][39][40] has been prepared to summarize endophyte strains that can be potentially employed for specific plants and properties that have been enhanced (Table 1). It was demonstrated that plant growth promoting (PGP) abilities and biological nitrogen fixation, followed by the production of secondary metabolites and bioactive compounds, synthesis of fungicides and bactericides, and protection against environmental stresses are the most important benefits that are provided to plants by endophytes (Table 1).…”

“…Plant growth promoting bacteria (PGPB) can be defined as representatives of biota that can stimulate the growth of the host, for example, rhizobacteria, when they grow in association with host plants [13,43,44]. Endophytic organisms can stimulate and intensify plant growth through the following mechanisms [16,17,24]:…”

Midgut microbiota diversity of potato tuber moth associated with potato tissue consumed

“…Diet is a very important factor in shaping the gut microbiota of insects [31,44]. Plant endophytic bacteria might exist in plant-feeding insects and help regulate insect development [20,45]. In our study, PTM midgut microbes and potato endophytic communities showed significant differences.…”

“…Some endophytic bacteria from plant tissues might be the same as those present in the insect gut [20], and can establish microbial communities in plant-feeding insect guts after transference from a plant [21]. Some studies have shown that many bacterial endophytes colonize the inner tissues of potato organs [22][23][24] and can promote growth and enhanced resistance of potato plants to pathogenic bacteria and fungi [25][26][27].…”