Polar growth in pollen tubes is associated with spatially confined dynamic changes in cell mechanical properties.
Cellular morphogenesis involves changes to cellular size and shape which in the case of walled cells implies the mechanical deformation of the extracellular matrix. So far, technical challenges have made quantitative mechanical measurements of this process at subcellular scale impossible. We used micro-indentation to investigate the dynamic changes in the cellular mechanical properties during the onset of spatially confined growth activities in plant cells. Pollen tubes are cellular protuberances that have a strictly unidirectional growth pattern. Micro-indentation of these cells revealed that the initial formation of a cylindrical protuberance is preceded by a local reduction in cellular stiffness. Similar cellular softening was observed before the onset of a rapid growth phase in cells with oscillating growth pattern. These findings provide the first quantitative cytomechanical data that confirm the important role of the mechanical properties of the cell wall for local cellular growth processes. They are consistent with a conceptual model that explains pollen tube oscillatory growth based on the relationship between turgor pressure and tensile resistance in the apical cell wall. To further confirm the significance of cell mechanics, we artificially manipulated the mechanical cell wall properties as well as the turgor pressure. We observed that these changes affected the oscillation profile and were able to induce oscillatory behavior in steadily growing tubes.
Zerzour
Rabah
R
Institut de recherche en biologie végétale, Département de sciences biologiques, Université de Montréal, 4101 rue Sherbrooke est, Montréal Québec, Canada H1X 2B2.
Kroeger
Jens
J
Geitmann
Anja
A
D001683:Biological Clocks; D002265:Carboxylic Ester Hydrolases / Q000494:pharmacology; D048430:Cell Shape; D002473:Cell Wall / Q000648:ultrastructure; D005583:Fourier Analysis; D007210:Indoleacetic Acids / Q000494:pharmacology; D027762:Lilium; D009024:Morphogenesis; D009994:Osmolar Concentration; D009997:Osmotic Pressure; D010207:Papaver; D032306:Petunia; D053205:Pollen Tube / Q000166:cytology / Q000187:drug effects / Q000254:growth & development*; D013314:Stress, Mechanical; D014026:Nicotiana
D007210:Indoleacetic Acids; C030737:indoleacetic acid; D002265:Carboxylic Ester Hydrolases; C022323:pectinesterase