Plant Cell Responses To Mechanical Stresses: Morphology, Growth, And Development

To survive in a wide range of various conditions in which they are exposed to, plants must respond to both endogenous and exogenous stimuli starting with a transduction of chemical and mechanical factors into a biological signal and ending into a global response as modification of growth. It has been generally recognized that perception and response to mechanical stresses are likely essential at the cellular level. Plant cells are highly susceptible and receptive to the physical factors in both nature and experimental conditions, where exposure to mechanical forces dramatically results in morphological and developmental alterations in their growth. In the current study, protoplasts and wall-reserved intact cells derived from chrysanthemum (Dendranthema morifolium) are subjected to a constant mechanical force conducted by agarose matrix. This form of investigation on mechanoregulated cell growth provides insight into how mechanical stresses can influence the cellular decisions, such as expansion, division, and wall development, which are suggested to be critical to morphogenesis and tissue patterning of plants. The results help to elucidate the potential role of mechanical factors in plants growth and development, and provide an acceptable approach, by which the physiological status of plants could be altered by external mechanical stimulations.The experimental studies are processed on the basis of a mechanical loading and testing system, which consists of a fabricated apparatus (including a loading unit, displacement sensor, data collector and processor, and a feedback control) and a protocol for test specimen preparation and forces loading. By using a force-feedback control circuit coupled to a microchip, delivering the pre-defined and actual controlled stimulus is achieved. Protoplasts and wall-reserved intact cells are embedded into agarose block. Constant uniaxial pressure provided by the apparatus is imposed on the opposite sides of the block. After that, the loaded cell-gel block is submerged in liquid medium for 4-7 days, and chipped to slices before microscopical analysis. The mechanical property of the cells-gel block is estimated on the basis of the theory of elastic mechanics. The solid blocks filled with living cells are idealized as homogeneous, isotropic and linearly elastic. The geometrical data of the solid block are submitted to commercial software ABAQUS, by which the geometry of the model is reconstructed. Static mechanical analysis of this model is conducted using the ABAQUS program on the basis of the finite element method, and then the distribution of principal stress in the...