Abstract
Cotton seedling disease caused by Pythium ultimum Trow and Rhizoctonia solani Kühn occurs worldwide in soils ranging from pH 4.5 to 8.5. Studies with cotton have not yet established the relative importance of two classes of secondary metabolites synthesized by soilborne pseudomonads, siderophores (sid) (low molecular weight Fe⁺³ chelators) and antibiotics (ant), in the suppression of these pathogens. Greenhouse bioassays to screen for rhizosphere competent strains identified a single strain of Pseudomonas chlororaphis (L-850), that produced siderophores and multiple antifungal antibiotics, including one or more phenazines. A Tiff Image Analyzer (TIA) software program was developed that allowed assessment of wild-type (wt) L-850, and (ant) and (sid) mutant populations as a function of cotton root surface area (cm²) in the absence of soil irrigation. Bacterial density and distribution patterns on roots evaluated 22, 36, and 50 DAP, in two pathogen-free soils (pH 5.7, high Fe⁺³, high phosphorus (P); pH 8.0, low Fe⁺³, low P) indicated that populations of both wt and mutants persisted after day 22 at levels between log 4.6 (lower laterals) to log 6 cfu/cm² (upper tap) even as total root area increased 122% from day 22 to 50. Population densities of all strains were consistently 1/8 to 3/4 log unit lower in the pH 5.7 soil on the lower tap and upper lateral roots, respectively. The loss of siderophore production appeared to enhance the rhizosphere competence of strain L-850. For greenhouse trials with three pathogen inoculum densities (low, intermediate, high) protection against preand postemergence damping-off (phase 1) and hypocotyl/root rot of young plants (phase 2) by the (sid) and wt strains was similar (P = 0.05) whereas, protection by seed treatment with the (ant) mutant was reduced. The level of suppression provided by L-850 was equivalent (P = 0.05) to the standard fungicide at low and intermediate pathogen pressure. These studies demonstrated a minimum contribution of siderophores in the biological control of cotton seedling disease and established a significant role for antibiotic biosynthesis over a range of soil physical and chemical characteristics.
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Claims 10
Claim · model-written summary
A rhizosphere competent Pseudomonas chlororaphis strain L-850 produced siderophores and antifungal antibiotics.
- Taxon
- Pseudomonas chlororaphisPseudomonas chlororaphise0
- Material
- L-850e0
- Outcome
- produced siderophores and multiple antifungal antibioticse0
Verbatim
e0“Greenhouse bioassays to screen for rhizosphere competent strains identified a single strain of Pseudomonas chlororaphis (L-850), that produced siderophores and multiple antifungal antibiotics, including one or more phenazines.”
Claim · model-written summary
The Tiff Image Analyzer allowed assessment of bacterial populations as a function of cotton root surface area.
- Taxon
- cotton
Gossypium hirsutumt0 - Outcome
- assessment of wild-type (wt) L-850, and (ant) and (sid) mutant populationse0
- Value
- cm²e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“A Tiff Image Analyzer (TIA) software program was developed that allowed assessment of wild-type (wt) L-850, and (ant) and (sid) mutant populations as a function of cotton root surface area (cm²) in the absence of soil irrigation.”
t0“cotton”
Claim · model-written summary
Wild type and mutant populations persisted after day 22 at log 4.6 to log 6 cfu/cm² across roots.
- Taxon
- cottonGossypium hirsutumt0
- Outcome
- populations of both wt and mutants persistede0
- Value
- log 4.6 (lower laterals) to log 6 cfu/cm²e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“populations of both wt and mutants persisted after day 22 at levels between log 4.6 (lower laterals) to log 6 cfu/cm² (upper tap) even as total root area increased 122% from day 22 to 50.”
t0“cotton”
Claim · model-written summary
Cotton total root area increased 122% from day 22 to 50.
- Taxon
- cottonGossypium hirsutumt0
- Outcome
- total root areae0
- Direction
- increasede0
- Value
- 122%e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“total root area increased 122% from day 22 to 50”
t0“cotton”
Claim · model-written summary
All bacterial strains had lower densities in pH 5.7 than pH 8.0 soil on specified roots.
- Taxon
- cottonGossypium hirsutumt0
- Outcome
- Population densities of all strainse0
- Direction
- lowere0
- Value
- 1/8 to 3/4 log unite0
- Setting
- pH 5.7 soile0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Population densities of all strains were consistently 1/8 to 3/4 log unit lower in the pH 5.7 soil on the lower tap and upper lateral roots, respectively.”
t0“cotton”
Claim · model-written summary
Loss of siderophore production appeared to enhance L-850 rhizosphere competence.
- Taxon
- cottonGossypium hirsutumt0
- Interactor
- strain L-850e0
- Outcome
- rhizosphere competencee0
- Direction
- enhancee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The loss of siderophore production appeared to enhance the rhizosphere competence of strain L-850.”
t0“cotton”
Claim · model-written summary
Siderophore deficient and wild type strains provided similar cotton damping-off and rot protection.
- Taxon
- cottonGossypium hirsutumt0
- Treatment
- (sid)e0
- Outcome
- protection against preand postemergence damping-off (phase 1) and hypocotyl/root rote0
- Direction
- similare0
- Comparator
- wt strainse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“protection against preand postemergence damping-off (phase 1) and hypocotyl/root rot of young plants (phase 2) by the (sid) and wt strains was similar (P = 0.05)”
t0“cotton”
Claim · model-written summary
Antibiotic deficient seed treatment provided reduced protection.
- Taxon
- cottonGossypium hirsutumt0
- Treatment
- seed treatment with the (ant) mutante0
- Outcome
- protectione0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“protection by seed treatment with the (ant) mutant was reduced.”
t0“cotton”
Claim · model-written summary
L-850 disease suppression matched standard fungicide under low and intermediate pathogen pressure.
- Taxon
- cottonGossypium hirsutumt0
- Treatment
- L-850e0
- Outcome
- level of suppressione0
- Direction
- equivalente0
- Qualifier
- low and intermediate pathogen pressuree0
- Comparator
- standard fungicidee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The level of suppression provided by L-850 was equivalent (P = 0.05) to the standard fungicide at low and intermediate pathogen pressure.”
t0“cotton”
Claim · model-written summary
The study concludes siderophores made a minimum contribution and antibiotic synthesis a significant contribution to cotton disease control.
- Taxon
- cottonGossypium hirsutumt0
- Outcome
- biological control of cotton seedling diseasee0
- Qualifier
- antibiotic biosynthesise0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“These studies demonstrated a minimum contribution of siderophores in the biological control of cotton seedling disease and established a significant role for antibiotic biosynthesis over a range of soil physical and chemical characteristics.”
t0“cotton”
The same questions in other papers
seed treatment · control · Gossypium hirsutum (cotton)Positive and negative results
1 paper in the same direction as this paper · 3 in the opposite direction
- positive
- positive
- positive
1 paper more in this group
See all 5 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.