Thigmotropic response

Chemicals can also induce infection structures, and each fungus seems to have its own requirement. For example, Puccinia graminis tritici responds to acrolein (16), while U. appendiculatus responds to K+ (17). The thigmotropic response by U. appendiculatus to the stomate, however, is entirely physical as demonstrated by Wynn (8). 

The increased erosion (weathering) of plant cuticles by simulated "rain acidified with sulfuric acid may disrupt processes that occur at the leaf surface. The most important function of the cuticle is to reduce water (transpiration) loss. > Removal of leaf surface waxes has been reported to increase wettability of those surfaces.Leaves which had been wetted and dried are subsequently wetted more easily.The water repellency of a plant surface is important in preventing the establishment of infections from water-borne inocula.Dickinson proposed that the thigmotropic response of germ tubes of certain fungi is a function of the structure and thickness of the cuticle. Both of these features of cuticular waxes appear to be altered by simulated rain acidified with sulfuric acid. The apparent loss of surface... 

Thigmotropism is the response of living matter to mechanical stimulation. Examples of this form of irritability appear to be far less common among plants than among animals. Certain species... 

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