the present invention provides a method of reducing the period within which a plant &# 39 ; s natural defence mechanism responds to attack by a plant pathogen , the method comprising causing the plant to maintain , in at least a part of the plant , a level of bip , or a homologue thereof , which is greater than the endogenous level for said plant in non - stressful conditions . increased bip levels can be achieved by transformation with a nucleic acid encoding bip or calreticulin or modifying signal transduction pathways leading to bip induction . bip levels can be increased above endogenous levels by over - expressing bip or calreticulin . the invention also provides for a modified plant produced by the method of the invention .