Abstract
SUMMARY Graminaceous plant species respond to iron (Fe)‐deficiency stress by enhancing the release of phytosiderophores from the roots and the uptake of Fe‐phytosiderophores. For studying the mobilization and uptake of apoplasmic root Fe by barley (inherently high phytosiderophore release) and sorghum (inherently low phytosiderophore release) in axenic and nonaxenic (inoculated) nutrient solution, Fe pools in the root apoplasm were loaded during plant preculture with 10 ‐4 M Fe(III)‐EDTA. After 27 d growth in Fe‐deficient nutrient solution, inoculated barley plants developed moderate Fe‐deficiency chlorosis compared with the less chlorotic axenic plants. In inoculated plants, recovery of phytosiderophores and mobilization of apoplasmic root Fe tended to be slightly lower than in axenic plants, and in both treatments apoplasmic root Fe was completely depleted at harvest. As determined by the nonsoluble Fe fraction (> 0·2 μm) in the nutrient solution and at the rhizoplane, the microbial uptake and immobilization of apoplasmic root Fe was estimated at about 3% of the total amount of apoplasmic root Fe after preculture and at less than 10% of plant Fe uptake. Under axenic conditions, Fe‐deficient sorghum also depleted apoplasmic root Fe and developed moderate Fe‐deficiency chlorosis, although phytosiderophore recovery was 5‐10‐fold lower than in barley. By contrast, in inoculated sorghum plants, phytosiderophore recovery and Fe mobilization were extremely low. At harvest, in inoculated sorghum plants apoplasmic Fe pools were still considerably loaded and plant Fe uptake was c. 60% lower than that of axenic plants, resulting in severe Fe‐deficiency chlorosis. Thus, in Fe‐deficient sorghum plants, the lower rate of phytosiderophore release and its degradation restricted an efficient mobilization of apoplasmic root Fe in the presence of micro‐organisms. In barley, however, the higher rate of phytosiderophore release allowed a complete mobilization of apoplasmic root Fe even in inoculated nutrient solution. Furthermore, the results show that the dominating effect of micro‐organisms in their competition with barley and sorghum for apoplasmic root Fe is the degradation of phytosiderophores rather than the immobilization or uptake of Fe.
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Claims 14
Claim · model-written summary
Inoculated barley developed more iron-deficiency chlorosis than axenic barley.
- Taxon
- barley
.jpg?width=60)
Hordeum vulgaret0 - Treatment
- inoculatede0
- Outcome
- Fe‐deficiency chlorosise0
- Direction
- less chlorotice0
- Qualifier
- After 27 d growth in Fe‐deficient nutrient solutione0
- Comparator
- axenic plantse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)
Verbatim
e0“After 27 d growth in Fe‐deficient nutrient solution, inoculated barley plants developed moderate Fe‐deficiency chlorosis compared with the less chlorotic axenic plants.”
t0“barley”
Claim · model-written summary
Inoculation tended to lower phytosiderophore recovery in barley.
- Taxon
- barleyHordeum vulgaret0
- Treatment
- inoculated plantse0
- Outcome
- recovery of phytosiderophorese0
- Direction
- slightly lowere0
- Comparator
- axenic plantse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In inoculated plants, recovery of phytosiderophores and mobilization of apoplasmic root Fe tended to be slightly lower than in axenic plants”
t0“barley”
Claim · model-written summary
Inoculation tended to lower mobilization of apoplasmic root Fe in barley.
- Taxon
- barleyHordeum vulgaret0
- Treatment
- inoculated plantse0
- Outcome
- mobilization of apoplasmic root Fee0
- Direction
- slightly lowere0
- Comparator
- axenic plantse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In inoculated plants, recovery of phytosiderophores and mobilization of apoplasmic root Fe tended to be slightly lower than in axenic plants”
t0“barley”
Claim · model-written summary
Barley depleted apoplasmic root Fe at harvest under both conditions.
- Taxon
- barleyHordeum vulgaret0
- Outcome
- apoplasmic root Fe was completely depletede0
- Qualifier
- both treatmentse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“in both treatments apoplasmic root Fe was completely depleted at harvest.”
t0“barley”
Claim · model-written summary
Microbes immobilized or took up about 3% of preculture root apoplasmic Fe, less than 10% of plant uptake.
- Taxon
- barleyHordeum vulgaret0
- Outcome
- microbial uptake and immobilization of apoplasmic root Fee0
- Value
- about 3%e0
- Qualifier
- less than 10% of plant Fe uptakee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the microbial uptake and immobilization of apoplasmic root Fe was estimated at about 3% of the total amount of apoplasmic root Fe after preculture and at less than 10% of plant Fe uptake.”
t0“barley”
Claim · model-written summary
Axenic sorghum depleted apoplasmic root Fe and developed moderate chlorosis.
- Outcome
- depleted apoplasmic root Fe and developed moderate Fe‐deficiency chlorosise0
- Qualifier
- Under axenic conditionse0
SorghumOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Under axenic conditions, Fe‐deficient sorghum also depleted apoplasmic root Fe and developed moderate Fe‐deficiency chlorosis”
t0“sorghum”
Claim · model-written summary
Sorghum phytosiderophore recovery was 5–10 times lower than barley.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“phytosiderophore recovery was 5‐10‐fold lower than in barley.”
t0“sorghum”
Claim · model-written summary
In inoculated sorghum, phytosiderophore recovery and Fe mobilization were extremely low.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“in inoculated sorghum plants, phytosiderophore recovery and Fe mobilization were extremely low.”
t0“sorghum”
Claim · model-written summary
Inoculated sorghum retained considerable apoplasmic Fe at harvest.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“At harvest, in inoculated sorghum plants apoplasmic Fe pools were still considerably loaded”
t0“sorghum”
Claim · model-written summary
Inoculated sorghum had about 60% lower Fe uptake than axenic plants.
- Treatment
- inoculated sorghum plantse0
- Outcome
- plant Fe uptakee0
- Direction
- lowere0
- Value
- c. 60%e0
- Comparator
- axenic plantse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“At harvest, in inoculated sorghum plants apoplasmic Fe pools were still considerably loaded and plant Fe uptake was c. 60% lower than that of axenic plants”
t0“sorghum”
Claim · model-written summary
Inoculated sorghum developed severe iron-deficiency chlorosis.
- Outcome
- severe Fe‐deficiency chlorosise0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“resulting in severe Fe‐deficiency chlorosis.”
t0“sorghum”
Claim · model-written summary
The authors attribute limited sorghum Fe mobilization in the presence of microbes to low phytosiderophore release and degradation.
- Outcome
- mobilization of apoplasmic root Fee0
- Qualifier
- lower rate of phytosiderophore release and its degradatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the lower rate of phytosiderophore release and its degradation restricted an efficient mobilization of apoplasmic root Fe in the presence of micro‐organisms.”
t0“sorghum”
Claim · model-written summary
High phytosiderophore release allowed barley to mobilize root apoplasmic Fe completely despite inoculation.
- Taxon
- barleyHordeum vulgaret0
- Outcome
- complete mobilization of apoplasmic root Fee0
- Qualifier
- higher rate of phytosiderophore releasee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the higher rate of phytosiderophore release allowed a complete mobilization of apoplasmic root Fe even in inoculated nutrient solution.”
t0“barley”
Claim · model-written summary
The authors identify phytosiderophore degradation as the dominant microbial competition effect.
- Taxon
- barleyHordeum vulgaret0
- Outcome
- degradation of phytosiderophorese0
- Qualifier
- competition with barley and sorghum for apoplasmic root Fee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the dominating effect of micro‐organisms in their competition with barley and sorghum for apoplasmic root Fe is the degradation of phytosiderophores rather than the immobilization or uptake of Fe.”
t0“barley”
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See all 39 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.