Hypersensibility

Chemical reaction, usually caused by phenolic substances called phytoalexins, which are manifested in parts of plants attacked by pathogens, killing the cells around the lesion, thus stopping the biological condition from spreading. Some examples of such substances that make plants more resistant to diseases are the following:

a) in bean phaseolin resistant Rhizoctonia solani;

b) pisatina in pea resistant to Fusarium solani;

c) chlorogenic acid in coffee Ceratocystis fimbriata resistant and resistant potato Streptomayces scabies. The hypersensitivity reaction caused by the synthesis of phytoalexins, should not be confused with vertical resistance, because it is not complex, and is influenced by environmental and nutritional factors.