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Submitted to: APS Annual Meeting
Publication Type: Abstract Only Publication Acceptance Date: 5/12/2014 Publication Date: 8/9/2014 Citation: Funnell-Harris, D.L., Sattler, S.E. 2014. Characterization of fluorescent pseudomonas spp. associated with roots and soil of two sorghum genotypes. APS Annual Meeting. http://www.apsnet.org/meetings/Documents/2014_meeting_abstracts/aps2014abO71.htm. Interpretive Summary: Technical Abstract: Sorghum, useful for bioenergy feedstock, animal feed, and food, requires economical methods for disease prevention and control. Fluorescent Pseudomonas spp. were isolated from sorghum roots and adherent soil to identify isolates that inhibited sorghum fungal pathogens. Pseudomonads were collected from seedlings of sorghum cultivars RTx433 and Redlan and wheat cultivar Lewjain, grown in two soils. Lewjain supports 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 and plant type affected HCN- and protease-production, but phlD was unaffected. phlD+ isolates were chosen to determine phlD genotypes and to conduct in vitro inhibition assays against sorghum pathogens. Most isolates were genotype D, previously associated with superior root colonization. phlD+ sorghum isolates were co-cultured with five pathogens. One isolate from each sorghum line inhibited all five pathogens but more Redlan isolates were inhibitory to the virulent pathogen, Fusarium thapsinum, than RTx433 isolates. Nearly all inhibitory isolates from both cultivars were from one soil. This is consistent with previous observations from sorghum field studies: soil type played a significant role in determining characteristics of fluorescent pseudomonads, but sorghum genotype also had a considerable effect. |
