Abstract
Sinorhizobium meliloti nodulation factors (NFs) elicit a number of symbiotic responses in alfalfa (Medicago sativa) roots. Using a semiquantitative nodulation assay, we have shown that chemically synthesized NFs trigger nodule formation in the same range of concentrations (down to 10(-10) M) as natural NFs. The absence of O-sulfate or O-acetate substitutions resulted in a decrease in morphogenic activity of more than 100-fold and approximately 10-fold, respectively. To address the question of the influence of the structure of the N-acyl chain, we synthesized a series of sulfated tetrameric lipo-chitooligosaccharides (LCOs) having fatty acids of different lengths and with unsaturations either conjugated to the carbonyl group (2E) or located in the middle of the chain (9Z). A nonacylated, sulfated chitin tetramer was unable to elicit nodule formation. Acylation with short (C8) chains rendered the LCO active at 10(-7) M. The optimal chain length was C16, with the C16-LCO being more than 10-fold more active than the C12- and C18-LCOs. Unsaturations were important, and the diunsaturated 2E,9Z LCO was more active than the monounsaturated LCOs. We discuss different hypotheses for the role of the acyl chain in NF perception.
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Claims 7
Claim · model-written summary
Chemically synthesized S. meliloti nodulation factors trigger nodule formation on alfalfa at the same concentrations as natural factors.
- Taxon
- alfalfa
Medicago sativae0 - Treatment
- chemically synthesized NFse1
- Interactor
- Sinorhizobium meliloti
Sinorhizobium melilotie0symbiont - Outcome
- nodule formatione1
- Direction
- triggere1
- Comparator
- natural NFse1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Sinorhizobium meliloti nodulation factors (NFs) elicit a number of symbiotic responses in alfalfa (Medicago sativa) roots”
e1“chemically synthesized NFs trigger nodule formation in the same range of concentrations (down to 10(-10) M) as natural NFs”
Claim · model-written summary
Absence of O-sulfate substitution decreased nodulation activity of S. meliloti factors on alfalfa by more than 100-fold.
- Taxon
- alfalfaMedicago sativae0
- Treatment
- absence of O-sulfatee2
- Interactor
- Sinorhizobium melilotiSinorhizobium melilotie0symbiont
- Outcome
- morphogenic activitye2
- Direction
- decreasee2
- Value
- more than 100-folde2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Sinorhizobium meliloti nodulation factors (NFs) elicit a number of symbiotic responses in alfalfa (Medicago sativa) roots”
e2“The absence of O-sulfate or O-acetate substitutions resulted in a decrease in morphogenic activity of more than 100-fold and approximately 10-fold, respectively”
Claim · model-written summary
Absence of O-acetate substitution decreased nodulation activity of S. meliloti factors on alfalfa by approximately 10-fold.
- Taxon
- alfalfaMedicago sativae0
- Treatment
- O-acetate substitutionse2
- Interactor
- Sinorhizobium melilotiSinorhizobium melilotie0symbiont
- Outcome
- morphogenic activitye2
- Direction
- decreasee2
- Value
- approximately 10-folde2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Sinorhizobium meliloti nodulation factors (NFs) elicit a number of symbiotic responses in alfalfa (Medicago sativa) roots”
e2“The absence of O-sulfate or O-acetate substitutions resulted in a decrease in morphogenic activity of more than 100-fold and approximately 10-fold, respectively”
Claim · model-written summary
A nonacylated, sulfated chitin tetramer was unable to elicit nodule formation on alfalfa.
- Taxon
- alfalfaMedicago sativae0
- Material
- nonacylated, sulfated chitin tetramere3
- Interactor
- Sinorhizobium melilotiSinorhizobium melilotie0symbiont
- Outcome
- nodule formatione3
- Direction
- unable to elicite3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Sinorhizobium meliloti nodulation factors (NFs) elicit a number of symbiotic responses in alfalfa (Medicago sativa) roots”
e3“A nonacylated, sulfated chitin tetramer was unable to elicit nodule formation”
Claim · model-written summary
Acylation with short C8 chains made the LCO active on alfalfa at 10(-7) M.
- Taxon
- alfalfaMedicago sativae0
- Treatment
- Acylation with short (C8) chainse4
- Interactor
- Sinorhizobium melilotiSinorhizobium melilotie0symbiont
- Compound
- LCOe4
- Outcome
- activee4
- Direction
- renderede4
- Value
- 10(-7) Me4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Sinorhizobium meliloti nodulation factors (NFs) elicit a number of symbiotic responses in alfalfa (Medicago sativa) roots”
e4“Acylation with short (C8) chains rendered the LCO active at 10(-7) M”
Claim · model-written summary
The C16-LCO was more than 10-fold more active than the C12- and C18-LCOs on alfalfa.
- Taxon
- alfalfaMedicago sativae0
- Interactor
- Sinorhizobium melilotiSinorhizobium melilotie0symbiont
- Compound
- C16-LCOe5
- Outcome
- activee5
- Direction
- more activee5
- Value
- more than 10-folde5
- Comparator
- C12- and C18-LCOse5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Sinorhizobium meliloti nodulation factors (NFs) elicit a number of symbiotic responses in alfalfa (Medicago sativa) roots”
e5“The optimal chain length was C16, with the C16-LCO being more than 10-fold more active than the C12- and C18-LCOs”
Claim · model-written summary
The diunsaturated 2E,9Z LCO was more active on alfalfa than the monounsaturated LCOs.
- Taxon
- alfalfaMedicago sativae0
- Interactor
- Sinorhizobium melilotiSinorhizobium melilotie0symbiont
- Compound
- diunsaturated 2E,9Z LCOe6
- Outcome
- activee6
- Direction
- more activee6
- Comparator
- monounsaturated LCOse6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Sinorhizobium meliloti nodulation factors (NFs) elicit a number of symbiotic responses in alfalfa (Medicago sativa) roots”
e6“Unsaturations were important, and the diunsaturated 2E,9Z LCO was more active than the monounsaturated LCOs”
The same questions in other papers
nodulation factor · Sinorhizobium meliloti · Medicago sativa (alfalfa)Positive and negative results
2 papers in the same direction as this paper · 1 in the opposite direction
- negative
- positive
- positive
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.