Soil and root populations of fluorescent Pseudomonas spp. associated with seedlings and field-grown plants are affected by sorghum genotype

Abstract

Sorghum [Sorghum bicolor (L.) Moench] is valued for bioenergy, feed and food. Potential of sorghum genotypes to support differing populations of root-and soil-associated fluorescent Pseudomonas spp. or Fusarium spp., in two soils, was assessed. Culturable pseudomonads were enumerated from roots and soil of sorghum (Redlan and RTx433) and wheat (Lewjain) seedlings repeatedly grown in cycled soils in the growth chamber. Pseudomonads and Fusarium spp. were assessed from roots and soil of field-grown sorghum along with biological control traits hydrogen cyanide (HCN) and 2,4-diacetylphlorogluconol (phl) production. After four 4-week cycles, soil associated with Redlan seedlings had greater numbers of fluorescent pseudomonads than Lewjain. In dryland field conditions, RTx433 roots had greater numbers of pseudomonads than Redlan before anthesis but similar numbers after. There were no differences in numbers of pseudomonads from dryland soil or roots or soil of irrigated plants. Percentages of HCN-producing root isolates and phl soil isolates declined on irrigated Redlan plants, but percentages of HCN-producers increased in dryland conditions. Redlan roots had greater percentages of Fusarium isolates in the Gibberella fujikuroi complex. Results indicated that sorghum genotype affected rootassociated populations of fluorescent Pseudomonas spp. and Fusarium spp. across soil environments.

Effects of plant host species and plant community richness on streptomycete community structure

“…We investigated the structure of streptomycete communities in soils associated with different plant host species and across a gradient of plant community richness. Previous work has indicated that soil microbial communities are differentially impacted by host plant species (Mazzola et al ., ; Funnell‐Harris et al ., ) and by communities of varying diversity (Chung et al ., ; Lamb et al ., ). However, our data provide evidence for interaction between these two factors, with plant community characteristics altering the influence of individual host species on soil microbes.…”

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

“…Cycling of sorghum and wheat seedlings was conducted as previously described (Funnell-Harris et al 2010). Sorghum grain of cultivars Redlan and RTx433 were produced in greenhouses at University of Nebraska, Lincoln (UNL).…”

“…Soil used was collected from post-harvest sorghum plots at UNL research fields at Lincoln (2008) and Ithaca (2007), NE, as previously described (Funnell-Harris et al 2010). Soil at Lincoln was a Kennebec silt loam, a fine-silty, mixed, superactive, mesic Cumulic Hapladolls.…”

“…Prior to planting the experiment (soil samples from bulk soil), and at the end of each cycle (root and soil samples from each plant), numbers of fluorescent Pseudomonas spp. were determined as described in a previous publication (Funnell-Harris et al 2010).…”

“…colony forming units (cfu) per gram of fresh soil or roots was determined for each plant. Numbers of Pseudomonas isolates (cfu) per gram soil collected at Ithaca, NE during 2007, and cfu per gram roots or soil during cycling, were previously used in analyses in Funnell-Harris et al 2010.…”