HETEROLOGOUS CHITINASE GENE-EXPRESSION TO IMPROVE PLANT DEFENSE AGAINST PHYTOPATHOGENIC FUNGI

Agricultural crops worldwide suffer from a vast array of fungal diseas es which cause severe yield losses. Upon interaction with a pathogen, plants initiate a complex network of defense mechanisms, among which i s a dramatic increase in chitinase activity, Chitinases are capable of hydrolyzing chitin-containing fungal cell walls and are therefore tho ught to play a major role in the plant's response, One of the strategi es to increase plant tolerance to fungal pathogens is the constitutive overexpression of proteins involved in plant-defense mechanisms, The level of protection observed in transgenic plants harboring heterologo us chitinase genes varies, depending on the particular combination of enzyme, plant and pathogen tested. Nevertheless, most of these transge nic plants exhibit increased tolerance to fungal diseases relative to their non-transgenic counterparts. The combined expression of chitinas es with other plant-defense proteins such as glucanases and ribosome-i nactivating proteins further enhances the plant's resistance to fungal attack.