Endophytes of Grapevine Flowers, Berries, and Seeds: Identification of Cultivable Bacteria, Comparison with Other Plant Parts, and Visualization of Niches of Colonization

Abstract

Endophytic bacteria can colonize various plants and organs. However, endophytes colonizing plant reproductive organs have been rarely analyzed. In this study, endophytes colonizing flowers as well as berries and seeds of grapevine plants grown under natural conditions were investigated by cultivation as well as by fluorescence in situ hybridization. For comparison, bacteria were additionally isolated from other plant parts and the rhizosphere and characterized. Flowers, fruits, and seeds hosted various endophytic bacteria. Some taxa were specifically isolated from plant reproductive organs, whereas others were also detected in the rhizosphere, endorhiza or grape inflo/infructescence stalk at the flowering or berry harvest stage. Microscopic analysis by fluorescence in situ hybridization of resin-embedded samples confirmed the presence of the isolated taxa in plant reproductive organs and enabled us to localize them within the plant. Gammaproteobacteria (including Pseudomonas spp.) and Firmicutes (including Bacillus spp.) were visualized inside the epidermis and xylem of ovary and/or inside flower ovules. Firmicutes, mainly Bacillus spp. were additionally visualized inside berries, in the intercellular spaces of pulp cells and/or xylem of pulp, but also along some cell walls inside parts of seeds. Analysis of cultivable bacteria as well as microscopic results indicated that certain endophytic bacteria can colonize flowers, berries, or seeds. Our results also indicated that some specific taxa may not only derive from the root environment but also from other sources such as the anthosphere.

Bacterial biosynthesis of 1-aminocyclopropane-1-caboxylate (ACC) deaminase, a useful trait to elongation and endophytic colonization of the roots of rice under constant flooded conditions

“…The use of beneficial bacteria as agricultural inputs for increasing crop production needs the selection of competent PGPR with plant growth promoting traits. We performed a colonization assay to find competent endophytes, since colonization is essential for PGP effects produced by bacteria and the interaction of them with plants (Compant et al 2011). Rice is grown under constant flooded conditions in Iran.…”

Impact of metagenomic DNA extraction procedures on the identifiable endophytic bacterial diversity in Sorghum bicolor (L. Moench)

“…These genera have previously been detected/isolated from tissues of other graminaceous and non-graminaceous plants including maize, sugarcane, rice, poplar, grapevine and sunflower (Pereira et al, 2011;Magnani et al, 2010;Sun et al, 2008;Ulrich et al, 2008;Compant et al, 2011;Ambrosini et al, 2012), thus indicating that these genera are probably ubiquitous in endophytic environments. This study also shows that the structures of sorghum stem and root communities are significantly different, and this could be explained by the differences in the selectivity of recruitment processes of microbes into each niche environment (Hardoim et al, 2008).…”

Root-associated bacteria promote grapevine growth: from the laboratory to the field

“…The grapevine core microbiome imparts similar PGP characteristics independent of geographical location, suggesting the persistence of a core set of PGP traits that influence plant development (Marasco et al 2013). These bacteria can migrate from the root to the shoot of grapevine (Compant et al 2010;Compant et al 2011) surviving in the fruit (Bokulich N et al 2014;Gilbert J et al 2014). Moreover, recent works demonstrated how grape tissues can be colonized by both autochthonous and allochthonous bacteria (Compant et al 2013;Rolli et al 2015).…”