Isolation and characterisation of bacterial colonies from seeds and in vitro cultures of Fraxinus spp. from Italian sites

Abstract

Culturable bacteria were isolated from seeds, embryos and contaminated in vitro cultures of ash (Fraxinus excelsior L., F. ornus L. and F. angustifolia L.) and were identified using morphological and molecular analyses. Fourteen morphologically distinct isolates were recovered from seeds of Fraxinus spp. 16S rDNA sequencing categorised these isolates into ten separate genera. Three strains isolated from contaminated in vitro cultures, Pantoea agglomerans, Staphylococcus succinus and Aerococcus viridans, were used for comparative analysis with isolates from seeds. Antibiotic sensitivity testing of the isolated contaminants, including phytotoxicity of antibiotics on in vitro cultures of ash, was also investigated. Phytotoxic effects on explants immersed in ampicillin or cultured on medium containing ampicillin were negligible, however tetracycline, either alone or in combination with other antibiotics, had phytotoxic effects. We conclude that ampicillin is a suitable antibiotic to limit the growth of contaminating bacteria during the in vitro culture of ash.

The cypsela (achene) of Echinacea purpurea as a diffusion unit of a community of microorganisms

“…**P Ttest < 0.01 communities associated to seeds of different plants such as Oryza sativa (Verma et al 2017;Hardoim et al 2012;Ruiza et al 2011;Kaga et al 2009;Liu et al 2017b;Mano et al 2006), Phragmites australis (White et al 2017), Triticum aestivum (Díaz Herrera et al 2016), Hordeum vulgare ( R a h m a n e t a l . 2 0 1 8 ) , T y l o s e m a e s c u l e n t u m (Chimwamurombe et al 2016), Zea mays (Liu et al 2013;Rijavec et al 2007), Arachis hypogaea (Sobolev et al 2013), Phaseolus vulgaris (Rosenblueth et al 2012), Curcubita pepo (Fürnkranz et al 2012), Vitis vinifera (Compant et al 2011), Fraxinus (Donnarumma et al 2011), Nicotiana tabacum (Mastretta et al 2009), Eucalyptus (Ferreira et al 2008), and Coffea arabica (Vega et al 2005). The genus Sanguibacter was detected in E. purpurea seeds in a smaller percentage of isolates.…”

“…Seed-associated endophytes have been described as capable of performing different functions essential for the plant, such as phytohormone production (Shahzad et al 2017;Alibrandi et al 2018), seedling and plant growth promotion (Rahman et al 2018;White et al 2017;Hardoim et al 2012), siderophore production (Díaz Herrera et al 2016;Alibrandi et al 2018), as well as antifungal property and antibiotic production (Verma et al 2017;Fürnkranz et al 2012;Donnarumma et al 2011). Moreover, it has been recently shown in cereals that seed-associated bacteria have coevolved with the plant hosts during domestication, likely as a result of mutualistic reciprocal advantage (Abdullaeva et al 2021).…”

Contamination

“…. Seeds and embryos and in vitro cultures of ash had numerous bacterial contaminants (Donnarumma et al, 2011). It is used as a pretissue soak as well as incorporated into the culture medium.…”

“…Additionally, many plants have microbial contamination within the vascular system, some seeds (Donnarumma et al, 2011), and intercellular spaces in leaf mesophyll, xylem vessel lumen and intercellular spaces of callus (Miyazaki et al, 2011). Surfaces covered with thick wax such as the succulents and epidermal hairs (trichomes) can trap microorganisms.…”

<b>Biochemical characterization of systemic bacteria in bananas, sensitivity to antibiotics and plant phytotoxicity during shoot proliferation

“…However, the success of efforts to control microorganisms using substances, in particular those intended for controlling bacteria, the main sources of contamination during large-scale micropropagation, depends on the isolation, identification, and testing of the sensitivity of the bacteria to antibiotics. This is because control of these contaminants is only possible through the use of substances that are within the spectrum of effectiveness against these microorganisms (Thomas et al, 2008;Donnarumma et al, 2011).…”