Characterization of bacterial endophytes of sweet potato plants

Abstract

Endophytic bacteria associated with sweet potato plants (Ipomoea batatas (L.) Lam.) were isolated, identified and tested for their ability to fix nitrogen, produce indole acetic acid (IAA), and exhibit stress tolerance. Eleven different strains belonging to the genera, Enterobacter, Rahnella, Rhodanobacter, Pseudomonas, Stenotrophomonas, Xanthomonas and Phyllobacterium, were identified. Four strains were shown to produce IAA (a plant growth hormone) and one strain showed the ability to grow in nitrogen free medium and had the nitrogenase subunit gene, nifH. To determine if IAA production by the endophytes had any role in protecting the cells against adverse conditions, different stress tests were conducted. The IAA producer grew well in the presence of some antibiotics, UV and cold treatments but the response to pH, osmotic shock, thermal and oxidative treatments was the same for both the IAA producer and the no IAA producer. To determine if IAA produced by the strains was biologically relevant to plants, cuttings of poplar were inoculated with the highest IAA producing strain. The inoculated cuttings produced roots sooner and grew more rapidly than uninoculated cuttings. These studies indicate that endophytes of sweet potato plants are beneficial to plant growth.

Screening of cultivable endophytic bacterial isolates for their plant growth promoting activity in rice

“…Our results of root length are in accordance with the research findings of Khan et al (2009), who isolated the IAA producing endophyte from sweet potato and showed an excellent root growth when inoculated onto poplar plant (hybrid variety). Similarly, the EBIs isolated from mangrove are known to promote root length of rice seedlings derived from seeds inoculated with EBIs which proves that endophytes are beneficial to non-host plants (Deivanai Subramanian et al, 2014).…”

Variations in airborne bacterial communities at high altitudes over the Noto Peninsula (Japan) in response to Asian dust events

“…Proteobacteria members were the dominate species in the atmosphere over mountains (Bowers et al, 2012;Vaïtilingom et al, 2012;Temkiv et al, 2012), in the air samples collected on a tower (Fahlgren et al, 2010), and from the troposphere (DeLeon-Rodriguez et al, 2013;Kourtev et al, 2011). In the phylum proteobacteria, the families Phyllobacteriaceae, Methylobacteriaceae, and Xanthomonadaceae were predominately detected from the non-dust samples and are associated with plant bodies or surfaces (Mantelin et al, 2006;Fürnkranz et al, 2008;Khan and Doty, 2009;Fierer and Lennon, 2011). The Betaproteobacteria sequences in the non-dust samples mainly contained the Oxalobacteraceae and Comamonadaceae families, which are commonly dominate in freshwater environments (Nold and Zwart, 1998) and on plant leaves (Redford et al, 2010).…”

Activation of Nitrogen-Fixing Endophytes Is Associated with the Tuber Growth of Sweet Potato

“…3,4) Acetobacter diazotrophicus, an endophytic nitrogen-xing bacterium, has been isolated from aerial parts of eld-grown sweet potato, sugarcane, and sweet sorghum (Sorghum vulgare), 3,5) and various nitrogen-xing bacteria were shown to colonize the sago palm extensively. 6) In a recent study by Khan and Doty, 7) endophytic bacteria associated with sweet potato plants were isolated, identi ed, and tested for their ability to x nitrogen and exhibit stress tolerance.…”