Salicylic acid (aspirin) is not only reducing human disease symptoms but it is also one of the major
plant defense hormones, supporting the plants immunity to different diseases. Nevertheless, it is
still unclear how this hormone is being synthesized in rice. There are two possible biosynthesis
pathways, via isochorismate or via phenylalanine, and it is not clear which of these, or both are
important. Rice is also different from many other plants by its very high basal salicylic acid level in
leaves, but not in roots. There is a vast amount of evidence that salicylic acid is an important
defense pathway in rice, whether it is to above ground pathogens such as rice blast or to below
ground attackers such as rootknot nematodes. It has also been shown that fungal pathogens and
postulated for nematodes that they try to interfere with this pathway by the secretion of effector
proteins such as chorismate mutase. In nematodes, we have besides chorismate mutase also
identified an isochorismatase that could be involved in lowering the salicylic acid level in a succesfull
nematode infection. This project will unravel the importance of both paths to the biosynthesis of
salicylic acid in defense of rice and will analyse how nematodes interfere with this pathway to
facilitate infection.