Faba bean forisomes can function in defence against generalist aphids

Phloem sieve elements have shut‐off mechanisms that prevent loss of nutrient‐rich phloem sap when the phloem is damaged. Some phloem proteins such as the proteins that form forisomes in legume sieve elements are one such mechanism and in response to damage, they instantly form occlusions that stop t...

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Bibliographic Details
Published in:Plant, cell and environment cell and environment, 2015-06, Vol.38 (6), p.1167-1177
Main Authors: MEDINA‐ORTEGA, KARLA J, WALKER, GREGORY P
Format: Article
Language:English
Subjects:
Acyrthosiphon pisum
Animals
Aphids - physiology
calcium channel blockers
calcium signaling
EPG
faba beans
Feeding Behavior
host plant resistance
insects
insect‐plant‐interactions
lanthanum
Macrosiphum euphorbiae
Myzus persicae
Phloem - physiology
phloem occlusion
plant defense
Plant Leaves - physiology
proteins
P‐protein
sap
sap flow
sieve element
sieve elements
stylet penetration
stylets
Vicia faba
Vicia faba - physiology
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Summary:Phloem sieve elements have shut‐off mechanisms that prevent loss of nutrient‐rich phloem sap when the phloem is damaged. Some phloem proteins such as the proteins that form forisomes in legume sieve elements are one such mechanism and in response to damage, they instantly form occlusions that stop the flow of sap. It has long been hypothesized that one function of phloem proteins is defence against phloem sap‐feeding insects such as aphids. This study provides the first experimental evidence that aphid feeding can induce phloem protein occlusion and that the aphid‐induced occlusions inhibit phloem sap ingestion. The great majority of phloem penetrations in Vicia faba by the generalist aphids Myzus persicae and Macrosiphum euphorbiae triggered forisome occlusion and the aphids eventually withdrew their stylets without ingesting phloem sap. This contrasts starkly with a previous study on the legume‐specialist aphid, Acyrthosiphon pisum, where penetration of faba bean sieve elements did not trigger forisome occlusion and the aphids readily ingested phloem sap. Next, forisome occlusion was demonstrated to be the cause of failed phloem ingestion attempts by M. persicae: when occlusion was inhibited by the calcium channel blocker lanthanum, M. persicae readily ingested faba bean phloem sap.
ISSN:0140-7791
1365-3040
DOI:10.1111/pce.12470