Long-term acid-induced wall extension in an in-vitro system.
When frozen-thawed Avena sativa L. coleoptile and Cucumis sativa L. hypocotyl sections, under tension, are acid-treated, they undergo rapid elongation (acid-extension).  The acid-extension response consists of two concurrent phases:  a burst of extension which decays exponentially over 1-2 h (ExE), and a constant rate of extension (CE) which can persist for at least 6h.  The extension (delta L) is closely represented by the equation:  delta L = a-a e(-kt) + C t where a is the total extension of the exponential phase, k is the rate constant for ExE, and c is the rate of linear extension (CE).  Low pH and high tension increased a and c, whereas temperature influenced k.  The magnitude of the CE (over 50% extension/10 h), the similarity in its time course to auxin-induced growth, and the apparent yield threshold for CE indicate that CE is more likely than ExE to be the type of extension which cell walls undergo during normal auxin-induced growth.
Cleland
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RE
Department of Botany, University of Washington, Seattle 98195, USA.
Cosgrove
D
D
Tepfer
M
M
D018554:Avena / Q000166:cytology* / Q000187:drug effects / Q000254:growth & development*; D002473:Cell Wall / Q000502:physiology; D018548:Cotyledon / Q000166:cytology / Q000187:drug effects / Q000254:growth & development*; D018553:Cucumis sativus / Q000166:cytology* / Q000254:growth & development*; D006863:Hydrogen-Ion Concentration; D018546:Hypocotyl / Q000166:cytology / Q000254:growth & development*; D007210:Indoleacetic Acids / Q000494:pharmacology; D010937:Plant Growth Regulators / Q000494:pharmacology; D013696:Temperature; D013997:Time Factors
D007210:Indoleacetic Acids; D010937:Plant Growth Regulators; C030737:indoleacetic acid