ISSN:
1615-6102
Keywords:
Asteraceae
;
Thigmonasticity
;
Cuticle
;
Elasticity
;
Extensibility
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Summary Touching stimulates thistle (Cirsium horridulum Michx.) staminal filaments to rapidly shorten to approximately 70% of their original length. The filaments subsequently re-elongate and regain contractibility within 10min. This thigmonastic movement can be repeated at least 10 times in detached flowers. Filament length is reduced by bathing in 1 M sorbitol, indicating that length change depends on variation in turgor pressure, as is also indicated by plasmolysis observed in contracted filaments. Contraction also depends upon elastic properties of the cuticle. These properties of the cuticle are resistant to boiling in water, chloroform or acid, and treatment with proteases, protein denaturants, sulfatases, and many cell wall degrading enzymes, but are sensitive to cutinase, β-glucuronidase, and boiling in 1 M NaOH. Analysis of carbohydrates from flowers boiled in 1 N NaOH showed that most galacturonic acid residues were extracted from filaments but not from petals (which are inelastic). The filament galacturonic acid residues may form a part of the cuticular contractile mechanism, and/or they may facilitate the bending of the vascular and cortical cells that occurs during contraction. Our results indicate that the elasticity of the stretched cuticle provides the force for the contraction of the filaments and the build-up of turgor causes re-elongation.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01323341
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