Nutrient transport tubes in fava beans and other legumes are plugged quickly when damaged via shape-changing mechano-proteins called forisomes.

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"Sieve tubes in legumes contain forisomes, which are spindle-like bodies that are composed of ATP-independent, mechanically active proteins. Upon injury, forisomes occlude sieve tubes by dispersion and thus, help to prevent loss of nutrient-rich transport sap. Forisome enlargement by dispersion is brought about by Ca2+-induced conformational changes that confer radial expansion and longitudinal contraction. Forisomes recontract upon Ca2+ removal. In vitro, forisomes reversibly disperse and contract in the presence or absence of Ca2+, respectively, and at distinct pHs. Recently, forisomes have received renewed attention because of their unique capacity to convert chemical into mechanical energy independent of high-energy organic compounds. Forisome-based 'smart' materials can be used to produce self-powered monitoring and diagnostic systems." (Tuteja et al. 2010:102)

Journal article
Forisomes: calcium-powered protein complexes with potential as ‘smart’ biomaterialsTrends in BiotechnologyDecember 12, 2009
Narendra Tuteja, Pavan Umate, Aart J.E. van Bel

Journal article
The geometry of the forisome-sieve element-sieve plate complex in the phloem of Vicia faba L. leafletsJournal of Experimental BotanyAugust 2, 2006
W. S. Peters

Journal article
Molecular sabotage of plant defense by aphid salivaProceedings of the National Academy of SciencesJune 7, 2007
T. Will, W. F. Tjallingii, A. Thonnessen, A. J. E. van Bel

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