Cultivar and Metal-Specific Effects of Endophytic Bacteria in Helianthus tuberosus Exposed to Cd and Zn

Abstract

Plant growth promoting endophytic bacteria (PGPB) isolated from Brassica napus were inoculated in two cultivars of Helianthus tuberosus (VR and D19) growing on sand supplemented with 0.1 mM Cd or 1 mM Zn. Plant growth, concentrations of metals and thiobarbituric acid (TBA) reactive compounds were determined. Colonization of roots of H. tuberosus D19 by Pseudomonas sp. 262 was evaluated using confocal laser scanning microscopy. Pseudomonas sp. 228, Serratia sp. 246 and Pseudomonas sp. 262 significantly enhanced growth of H. tuberosus D19 exposed to Cd or Zn. Pseudomonas sp. 228 significantly increased Cd concentrations in roots. Serratia sp. 246, and Pseudomonas sp. 256 and 228 resulted in significantly decreased contents of TBA reactive compounds in roots of Zn exposed D19 plants. Growth improvement and decrease of metal-induced stress were more pronounced in D19 than in VR. Pseudomonas sp. 262-green fluorescent protein (GFP) colonized the root epidermis/exodermis and also inside root hairs, indicating that an endophytic interaction was established. H. tuberosus D19 inoculated with Pseudomonas sp. 228, Serratia sp. 246 and Pseudomonas sp. 262 holds promise for sustainable biomass production in combination with phytoremediation on Cd and Zn contaminated soils.

Systems Biology of Plant-Microbiome Interactions

“…Although many PGPRs, especially commercially available strains, colonize and exert beneficial effects on different plants, their performance can be strongly species or cultivar specific (Chanway et al, 1988;Germida and Walley, 1996;Montalban et al, 2017). Wheat cultivars differ in their colonization by and responsiveness to beneficial strains, such as Azospirillum brasilense (Rothballer et al, 2003;Walker et al, 2011) or Pseudomonas putida.…”

Seed Endophyte Microbiome of Crotalaria pumila Unpeeled: Identification of Plant-Beneficial Methylobacteria

“…Endophytic bacteria are also recognized as very important in respect of stress tolerance and plant growth [ 10 ]. Endophytes can promote plant growth and metal uptake directly by producing plant growth beneficial substances, phytohormones, siderophores and specific enzymes, metal mobilizing compounds, and biosurfactants; and, indirectly through controlling plant pathogens or by improving plant stress tolerance by producing 1-aminocyclopropane-1-carboxylate (ACC)-deaminase [ 10 , 11 ]. In contrast to the available amount of information on rhizospheric and shoot endophytic bacteria of metalliferous plants, very little is known about seed endophytes.…”

Phytostabilization of Polluted Military Soil Supported by Bioaugmentation with PGP-Trace Element Tolerant Bacteria Isolated from Helianthus petiolaris

“…B. proteolyticus ST89 significantly increased shoot biomass of H. annuus in the greenhouse and in vitro it was one of the strains that produced more IAA. Production of IAA by strains from the rhizosphere and endosphere of different crops, peanut, maize, wheat, and rice was already reported in a number of studies [31,46]. Biofilm producing strains were sought due to their ability to enhance bacterial attachment to the roots and concentrate trace elements into their extracellular polymeric structure [47,48].…”