Abstract
Summary Ecologists have become increasingly aware that silicon uptake by plants, especially the Poaceae, can have beneficial effects on both plant growth and herbivore defence. The effects of silicon on other plant functional groups, such as nitrogen‐fixing legumes, have been less well studied. Silicon could, however, indirectly promote herbivore performance in this group if reported increases in N 2 fixation caused improvements in host plant quality for herbivores. We tested how silicon supplementation in the legume ( Medicago sativa ) affected plant growth rates, root nodulation and foliage quality (silicon content and amino acid profiles) for an insect herbivore ( Acyrthosiphon pisum ). Plants supplemented with silicon (Si + ) grew three times as quickly as those without supplementation (Si − ), almost entirely in shoot mass. While root growth was unaffected by silicon uptake, root nodules containing nitrogen‐fixing bacteria were 44% more abundant on Si + plants. Aphid abundance was twice as high on Si + plants compared to Si − plants and was positively correlated with silicon‐stimulated plant growth. Si + plants accumulated more than twice as much silicon as Si − plants, but did not have higher silicon concentrations because of dilution effects linked to the rapid growth of Si + plants. Si + plants showed a 65% increase in synthesis of essential foliar amino acids, probably due to increased levels of root nodulation. These results suggest that increased silicon supply makes M. sativa more susceptible to A. pisum , mainly because of increased plant growth and resource availability (i.e. essential amino acids). While silicon augmentation of the Poaceae frequently improves herbivore defence, the current study illustrates that this cannot be assumed for other plant families where the beneficial effects of silicon on plant growth and nutrition may promote herbivore performance in some instances. A lay summary is available for this article.
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Claims 12
Claim · model-written summary
Silicon-supplemented Medicago sativa grew three times as quickly as unsupplemented plants.
- Taxon
- Medicago sativa
Medicago sativat0 - Treatment
- silicon (Si + )e0
- Outcome
- grewe0
- Direction
- three times as quicklye0
- Value
- three timese0
- Comparator
- without supplementation (Si − )e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Plants supplemented with silicon (Si + ) grew three times as quickly as those without supplementation (Si − )”
t0“the legume ( Medicago sativa )”
Claim · model-written summary
The silicon-linked growth difference was almost entirely shoot mass.
- Taxon
- Medicago sativaMedicago sativat0
- Outcome
- shoot masse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“almost entirely in shoot mass”
t0“the legume ( Medicago sativa )”
Claim · model-written summary
Silicon uptake did not affect root growth.
- Taxon
- Medicago sativaMedicago sativat0
- Treatment
- silicon uptakee0
- Outcome
- root growthe0
- Direction
- unaffectede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“root growth was unaffected by silicon uptake”
t0“the legume ( Medicago sativa )”
Claim · model-written summary
Nitrogen-fixing bacterial root nodules were 44% more abundant on silicon-supplemented plants.
- Taxon
- Medicago sativaMedicago sativat0
- Treatment
- Si +e0
- Interactor
- nitrogen‐fixing bacteriae0symbiont
- Outcome
- root nodules containing nitrogen‐fixing bacteriae0
- Direction
- more abundante0
- Value
- 44%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“root nodules containing nitrogen‐fixing bacteria were 44% more abundant on Si + plants”
t0“the legume ( Medicago sativa )”
Claim · model-written summary
Aphids were twice as abundant on silicon-supplemented plants as on unsupplemented plants.
- Taxon
- Medicago sativaMedicago sativat0
- Treatment
- Si +e0
- Interactor
- Aphide0pest
- Outcome
- Aphid abundancee0
- Direction
- twice as highe0
- Value
- twicee0
- Comparator
- Si −e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Aphid abundance was twice as high on Si + plants compared to Si − plants”
t0“the legume ( Medicago sativa )”
Claim · model-written summary
Aphid abundance was positively correlated with silicon-stimulated plant growth.
- Taxon
- Medicago sativaMedicago sativat0
- Treatment
- silicon‐stimulated plant growthe0
- Outcome
- Aphid abundancee0
- Direction
- positivelye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Aphid abundance was twice as high on Si + plants compared to Si − plants and was positively correlated with silicon‐stimulated plant growth”
t0“the legume ( Medicago sativa )”
Claim · model-written summary
Silicon-supplemented plants accumulated more than twice as much silicon as unsupplemented plants.
- Taxon
- Medicago sativaMedicago sativat0
- Treatment
- Si +e0
- Outcome
- accumulated more than twice as much silicone0
- Direction
- more than twicee0
- Value
- more than twicee0
- Comparator
- Si −e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Si + plants accumulated more than twice as much silicon as Si − plants”
t0“the legume ( Medicago sativa )”
Claim · model-written summary
Silicon concentrations were not higher in supplemented plants.
- Taxon
- Medicago sativaMedicago sativat0
- Treatment
- Si +e0
- Outcome
- silicon concentrationse0
- Direction
- did not have highere0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“but did not have higher silicon concentrations because of dilution effects linked to the rapid growth of Si + plants”
t0“the legume ( Medicago sativa )”
Claim · model-written summary
The authors attribute unchanged silicon concentration to dilution caused by rapid growth.
- Taxon
- Medicago sativaMedicago sativat0
- Outcome
- dilution effectse0
- Qualifier
- rapid growth of Si + plantse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“because of dilution effects linked to the rapid growth of Si + plants”
t0“the legume ( Medicago sativa )”
Claim · model-written summary
Supplemented plants increased synthesis of essential foliar amino acids by 65%.
- Taxon
- Medicago sativaMedicago sativat0
- Treatment
- Si +e0
- Outcome
- synthesis of essential foliar amino acidse0
- Direction
- increasee0
- Value
- 65%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Si + plants showed a 65% increase in synthesis of essential foliar amino acids”
t0“the legume ( Medicago sativa )”
Claim · model-written summary
The authors suggest greater nodulation probably explains increased essential amino acid synthesis.
- Taxon
- Medicago sativaMedicago sativat0
- Outcome
- increased levels of root nodulatione0
- Qualifier
- probablye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“probably due to increased levels of root nodulation”
t0“the legume ( Medicago sativa )”
Claim · model-written summary
The authors infer silicon supply makes alfalfa more susceptible to A. pisum through greater growth and essential amino acid availability.
- Taxon
- M. sativaMedicago sativae0
- Treatment
- increased silicon supplye0
- Interactor
- A. pisum
-PLoS.jpg?width=60)
Acyrthosiphon pisume0pest - Outcome
- more susceptible to A. pisume0
- Qualifier
- increased plant growth and resource availability (i.e. essential amino acids)e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
-PLoS.jpg?width=500)
Verbatim
e0“increased silicon supply makes M. sativa more susceptible to A. pisum , mainly because of increased plant growth and resource availability (i.e. essential amino acids)”
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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.