Mushrooms, illnesses a plant and stability to illnesses. Preexisting substances

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Many preexisting substances provide to plants some degree of stability to parasitic mushrooms. A leading role play it, obviously, saponiny (fig. 15.8) to which belong alkaloidy and triterpeny; in their molecule there is in a special way attached glikozilnaja a group giving to them water solubility. among protective substances it is a lot of glikozidov this type; at otshcheplenii glikozilnoj groups their water solubility is lost. These connections possess the expressed antimushroom action and, besides, ability to influence permeability and specific transport properties of membranes. Apparently, these their two features are somehow connected, because saponiny are concluded in vakuoli and if the mushroom gets into a cage cellular membranes are damaged and liberate corresponding saponin. Quite often saponin it is stored in the inactive form and it is activated, only having come into contact to special enzyme of cytoplasm. If at a mushroom membrane there is an enzyme r-glikozidaza it otshchepljaet from a molecule saponina gidroksilnuju group therefore saponin loses water solubility and passes already in lipidnuju a part of a cellular membrane. Here it influences some steriny membranes, translating them from liquid in more dense condition, is damages a cellular membrane of a mushroom and kills a mushroom cage. Not all mushrooms, however, are equally sensitive to such influence; at some mushrooms in a membrane are absent corresponding steriny, others possess ability inaktivirovat saponin and thereof keep stability to such protection.

Why the plants possessing such protective means how saponiny, can be susceptible to illness nevertheless? the matter is that these mechanisms, by definition, are inefficient against the presents patogenov. Their role consists in to allowing to other organisms to become patogenami. Thus, each plant is surprised any specific pathogenic organisms and remains steady against another which can amaze other kinds of plants in turn. Preexisting protective substances operate mainly on those mushrooms which strongly damage cages of a plant-owner and thus liberate or activate these protective substances. parasites who manage to locate in a plant, often enter into a cage the gaustorii - small shoots a floccus; gaustorii get through a cellular membrane and take from a cage nutrients, not too it damaging and consequently without causing in it any protective reactions. In other cases successful parasitism is provided with stability of a mushroom to antimushroom substances or its ability to destroy such substances thanks to what infectious process develops free.