Abstract
Sinorhizobium meliloti bacteria produce a signal molecule that enhances root respiration in alfalfa (Medicago sativa L.) and also triggers a compensatory increase in whole-plant net carbon assimilation. Nuclear magnetic resonance, mass spectrometry, and ultraviolet-visible absorption identify the enhancer as lumichrome, a common breakdown product of riboflavin. Treating alfalfa roots with 3 nM lumichrome increased root respiration 21% (P < 0.05) within 48 h. A closely linked increase in net carbon assimilation by the shoot compensated for the enhanced root respiration. For example, applying 5 nM lumichrome to young alfalfa roots increased plant growth by 8% (P < 0.05) after 12 days. Soaking alfalfa seeds in 5 nM lumichrome before germination increased growth by 18% (P < 0.01) over the same period. In both cases, significant growth enhancement (P < 0.05) was evident only in the shoot. S. meliloti requires exogenous CO2 for growth and may benefit directly from the enhanced root respiration that is triggered by lumichrome. Thus Sinorhizobium-alfalfa associations, which ultimately form symbiotic N2-reducing root nodules, may be favored at an early developmental stage by lumichrome, a previously unrecognized mutualistic signal. The rapid degradation of riboflavin to lumichrome under many physiological conditions and the prevalence of riboflavin release by rhizosphere bacteria suggest that events demonstrated here in the S. meliloti-alfalfa association may be widely important across many plant-microbe interactions.
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Claims 9
Claim · model-written summary
The S. meliloti respiration enhancer was identified as lumichrome.
- Taxon
- Sinorhizobium meliloti
Sinorhizobium melilotie1 - Interactor
- alfalfa
Medicago sativae1host - Outcome
- enhancer as lumichromee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Nuclear magnetic resonance, mass spectrometry, and ultraviolet-visible absorption identify the enhancer as lumichrome, a common breakdown product of riboflavin.”
e1“Sinorhizobium meliloti bacteria produce a signal molecule that enhances root respiration in alfalfa (Medicago sativa L.)”
Claim · model-written summary
Treating alfalfa roots with 3 nM lumichrome increased root respiration by 21% within 48 hours.
- Taxon
- alfalfaMedicago sativae0
- Treatment
- 3 nM lumichromee0
- Outcome
- root respiratione0
- Direction
- increasede0
- Value
- 21%e0
- Qualifier
- within 48 he0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Treating alfalfa roots with 3 nM lumichrome increased root respiration 21% (P < 0.05) within 48 h.”
Claim · model-written summary
Increased shoot carbon assimilation compensated for enhanced root respiration.
- Taxon
- alfalfaMedicago sativae1
- Outcome
- root respiratione0
- Direction
- enhancede0
- Qualifier
- increase in net carbon assimilation by the shoote0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“A closely linked increase in net carbon assimilation by the shoot compensated for the enhanced root respiration.”
e1“Treating alfalfa roots with 3 nM lumichrome”
Claim · model-written summary
Applying 5 nM lumichrome to young alfalfa roots increased growth by 8% after 12 days.
- Taxon
- alfalfaMedicago sativae0
- Organ / stage
- young alfalfa rootse0
- Treatment
- 5 nM lumichromee0
- Outcome
- plant growthe0
- Direction
- increasede0
- Value
- 8%e0
- Qualifier
- after 12 dayse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“applying 5 nM lumichrome to young alfalfa roots increased plant growth by 8% (P < 0.05) after 12 days.”
Claim · model-written summary
Soaking alfalfa seeds in 5 nM lumichrome increased growth by 18% over 12 days.
- Taxon
- alfalfaMedicago sativae0
- Treatment
- Soaking alfalfa seeds in 5 nM lumichromee0
- Outcome
- growthe0
- Direction
- increasede0
- Value
- 18%e0
- Qualifier
- after 12 dayse1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Soaking alfalfa seeds in 5 nM lumichrome before germination increased growth by 18% (P < 0.01) over the same period.”
e1“after 12 days.”
Claim · model-written summary
Root application produced significant growth enhancement only in the shoot.
- Taxon
- alfalfaMedicago sativae1
- Organ / stage
- shoote0
- Treatment
- applying 5 nM lumichromee1
- Outcome
- growthe0
- Direction
- enhancemente0
- Qualifier
- only in the shoote0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In both cases, significant growth enhancement (P < 0.05) was evident only in the shoot.”
e1“applying 5 nM lumichrome to young alfalfa roots”
Claim · model-written summary
Seed soaking produced significant growth enhancement only in the shoot.
- Taxon
- alfalfaMedicago sativae1
- Treatment
- Soaking alfalfa seeds in 5 nM lumichromee1
- Outcome
- growthe0
- Direction
- enhancemente0
- Qualifier
- only in the shoote0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In both cases, significant growth enhancement (P < 0.05) was evident only in the shoot.”
e1“Soaking alfalfa seeds in 5 nM lumichrome”
Claim · model-written summary
Lumichrome may favor early Sinorhizobium-alfalfa association development.
- Taxon
- alfalfaMedicago sativae0
- Interactor
- Sinorhizobium
.JPG?width=60)
Sinorhizobiume0symbiont - Compound
- lumichromee0
- Outcome
- Sinorhizobium-alfalfa associationse0
- Qualifier
- early developmental stagee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.JPG?width=500)
Verbatim
e0“Thus Sinorhizobium-alfalfa associations, which ultimately form symbiotic N2-reducing root nodules, may be favored at an early developmental stage by lumichrome, a previously unrecognized mutualistic signal.”
Claim · model-written summary
S. meliloti may benefit from lumichrome-triggered root respiration.
- Taxon
- S. melilotiSinorhizobium melilotie0
- Interactor
- alfalfaMedicago sativae1host
- Compound
- lumichromee0
- Outcome
- growthe0
- Qualifier
- enhanced root respiratione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“S. meliloti requires exogenous CO2 for growth and may benefit directly from the enhanced root respiration that is triggered by lumichrome.”
e1“root respiration in alfalfa”
The same questions in other papers
application · growth · Medicago sativa (alfalfa)Positive and negative results
26 papers in the same direction as this paper · 6 in the opposite direction
- no effect
- no effect
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See all 33 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.