Some fungi have evolved a highly sensitive mechanism for perceiving topographical signals from plant surfaces for accurately homing in on stomata. Contact of spore germ tube with the outermost waxy covering of the leaf triggers the differentiation of specialized cells that are required for generating mechanical force for puncturing the cuticle or for entry through minute stomatal aperture. Interestingly, formation of infection-related differentiation of cells can be induced on artificial hydrophobic membranes having multiple, closely spaced parallel ridges similar to that of cuticle, thereby confirming the role of physical signals in infection process. The observed thigmoresponse suggests a new approach for controlling rust disease through modification of topography. Moreover, thigmomorphogenesis-linked DNA synthesis and nuclear and cell divisions suggest new approach to axenic culture of biotrophic fungi.
Thigmotropism, plant cuticle, wheat rust, infection, disease control
