title: Expansins in growing tomato leaves.
abstract: An expansin-like protein from growing tomato leaves was identified by its ability to restore the 'acid-growth' response to heat-inactivated tomato walls and by its similarity to expansins from cucumber hypocotyls. Native walls from growing tomato leaves exhibit an endogenous acid-induced extension (creep) that resembles in various biochemical characteristics the acid-growth activity of cucumber hypocotyls. For example, the acid-growth activity is lost when the walls of tomato leaves are briefly heated and is largely restored by addition of a crude protein extract from the walls of growing leaves. Wall proteins from growing leaves enhance the stress relaxation spectrum of tomato walls in a fashion characteristic of cucumber expansins. HPLC fractionation of the crude wall protein from tomato leaves yielded an active fraction containing a major 27 kDa protein that cross-reacts with an antibody raised against cucumber expansin. The results show that tomato leafwalls possess at least one expansin that is responsible for the acid-growth property of leaves and indicate that cell wall extension in leaves shares an underlying protein mechanism common to cell wall expansion in stems.
authors.affiliation: Department of Horticulture, Pennsylvania State University, University Park 16802, USA.
authors.forename: E
authors.initials: E
authors.lastname: Keller
authors.forename: D J
authors.initials: DJ
authors.lastname: Cosgrove
mesh_terms: D002455:Cell Division; D002473:Cell Wall / Q000737:chemistry / Q000502:physiology; D018553:Cucumis sativus / Q000737:chemistry / Q000166:cytology* / Q000254:growth & development / Q000502:physiology; D018546:Hypocotyl / Q000737:chemistry / Q000166:cytology / Q000254:growth & development / Q000502:physiology; D018551:Solanum lycopersicum / Q000737:chemistry / Q000166:cytology* / Q000254:growth & development / Q000502:physiology; D018515:Plant Leaves / Q000737:chemistry / Q000166:cytology* / Q000254:growth & development / Q000502:physiology; D010940:Plant Proteins / Q000032:analysis* / Q000737:chemistry / Q000302:isolation & purification / Q000502:physiology
chemical_list: D010940:Plant Proteins; C095825:expansin protein, plant