Plant tissue cell lysis

Alfalfa Lysis. Whole alfalfa (Medicago sativa) plant tissue was broken and cell rupture was by shear in a rotary device. Juice expression was by a batch type press, as described elsewhere (17), The resulting alfalfa extract was stored, until required, at -20°C. 

All cells have to be broken open to remove the cell contents. To accomplish cell lysis the authors use a combination of homogenizing and grinding steps. For recalcitrant tissue a small rock grinder (i.e., ring grinder) is used. The authors advise the experimenter to perform a trial run on their plant material to establish the number and duration of homogenization steps. These should always be the minimum required to break open the cells. Excessive... 

Many cells are susceptible to the appreciable shearing forces that arise on repeated freezing and thawing, or to hypotonic buffers which cause cells to swell up, and in certain cases to lyse this is particularly the case for cells in soft plant and animal tissue. Such treatments only rarely lead to complete cell lysis, the exceptions to this being erythrocytes and reticulocytes which are lysed quantitatively under hypotonic conditions. Non-mechanical homogenisation is of particular relevance to cells like yeast which are refractory to other procedures. One of the simplest procedures for yeast, which can certainly not be described as gentle, is toluene-induced autolysis. This is carried out at room temperature and leads to permeabilisation of the cell walls this causes various hydrolases to be activated causing breakdown not only of the cell structure, but also (undesirably) of many sensitive proteins and nucleic acids in the cell. Consequently, this process is mainly of historical interest. 

Several mechanisms have evolved to prevent this catastrophe. In bacteria and plants, the plasma membrane is surrounded by a nonexpandable cell wall of sufficient rigidity and strength to resist osmotic pressure and prevent osmotic lysis. Certain freshwater protists that live in a highly hypotonic medium have an organelle (contractile vacuole) that pumps water out of the cell. In multicellular animals, blood plasma and interstitial fluid (the extracellular fluid of tissues) are maintained at an osmolarity close to that of the cytosol. The high concentration of albumin and other proteins in blood plasma contributes to its osmolarity. Cells also actively pump out ions such as Na+ into the interstitial fluid to stay in osmotic balance with their surroundings. 

Microbial 3-Glucan Hydrolases and Lysis of Plant Cell Wall Polymers. Many soil and aerial pathogens gain access to host tissues by enzymic lysis of epidermal cell walls of roots, leaves, stems, etc.. Phytopathogenic organisms possess an array of inducible polysaccharide hydrolases capable of degrading the complex polysaccharides of the plant cell wall (, 10). The... 

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