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The Arabidopsis trichome is an active mechanosensory switch
Author(s) -
Zhou Li Hong,
Liu Shao Bao,
Wang Peng Fei,
Lu Tian Jian,
Xu Feng,
Genin Guy M.,
Pickard Barbara G.
Publication year - 2017
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/pce.12728
Subject(s) - trichome , apoplast , arabidopsis , biophysics , arabidopsis thaliana , microbiology and biotechnology , biology , plant defense against herbivory , herbivore , botany , cell wall , biochemistry , mutant , gene
Trichomes (‘hair cells’) on Arabidopsis thaliana stem and leaf surfaces provide a range of benefits arising from their shape and disposition. These include tempting herbivores to sample constitutive toxins before they reach the bulk of the tissue. We asked whether, in addition, small mechanical disturbances such as an insect can make elicit signals that might help the plant respond to herbivory. We imaged, pressed and brushed trichomes in several ways, most notably with confocal microscopy of trichomes transgenically provided with apoplastic pH reporter apo‐pHusion and cytosolic Ca 2+ reporter cameleon. In parallel, we modelled trichome wall mechanics with finite element analysis. The stimulated trichome focuses force on a pliant zone and the adjoining podium of the stalk. A buckling instability can further focus force on a skirt of cells surrounding the podium, eliciting oscillations of cytosolic Ca 2+ and shifts in apoplastic pH. These observations represent active physiological response. Modelling establishes that the effectiveness of force focusing and buckling is due to the peculiar tapering wall structure of the trichome. Hypothetically, these active mechanosensing functions enhance toxin synthesis above constitutive levels, probably via a priming process, thus minimizing the costly accumulation of toxins in the absence of herbivore attack but assuring rapid build‐up when needed.