Characterization of fluorescent Pseudomonas spp. associated with roots and soil of two sorghum genotypes

Funnell-Harris, D.L. and Sattler, S.E. and Pedersen, J.F. (2013) Characterization of fluorescent Pseudomonas spp. associated with roots and soil of two sorghum genotypes. European Journal of Plant Pathology. pp. 1-13.

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Sorghum is used as bioenergy feedstock, animal feed, and food. Economical methods for disease prevention and control are valuable for producers. Fluorescent Pseudomonas spp. were isolated from sorghum roots and surrounding soil with the goal of finding isolates that significantly inhibited sorghum fungal pathogens. Fluorescent pseudomonads were collected from seedlings of sorghum cultivars RTx433 and Redlan and wheat cultivar Lewjain, grown in two soils. Lewjain is known to support growth of producers of the antibiotic, 2,4-diacetylphloroglucinol (2,4-DAPG). Isolates from all three plants were assessed for hydrogen cyanide (HCN) and extracellular protease production, and for a 2,4-DAPG gene, phlD. Both soil type and plant type affected HCN- and protease-production, but phlD was not affected. Subsets of phlD + isolates were chosen to determine phlD genotypes and to conduct in vitro inhibition assays against sorghum pathogens. Most isolates from sorghum and wheat were genotype D, previously associated with superior root colonization. phlD + sorghum isolates were co-cultured with five sorghum pathogens. One isolate from each sorghum line exhibited inhibition to all five pathogens but more Redlan isolates were inhibitory to the virulent pathogen, Fusarium thapsinum, than RTx433 isolates. Nearly all inhibitory isolates from either sorghum cultivar were from one soil type. This is consistent with what had been previously observed in field studies: that soil type played a significant role in determining characteristics of fluorescent Pseudomonas spp. isolated from roots or soil, but sorghum genotype also had a considerable effect.

Item Type: Article
Uncontrolled Keywords: 2,4-diacetylphloroglucinol – Fusarium thapsinum – Plant genotype – Soil type – Rhizobacteria – Sorghum bicolor (L.) Moench
Author Affiliation: Grain, Forage and Bioenergy Research Unit, Department of Plant Pathology, USDA-ARS and University of Nebraska, Lincoln, NE 68583-0937, USA
Subjects: Soil Science and Microbiology
Crop Improvement
Divisions: Sorghum
Depositing User: Mr B Krishnamurthy
Date Deposited: 25 May 2013 12:35
Last Modified: 25 May 2013 12:35
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