INDUCED SYSTEMIC RESISTANCE IN WOUNDED RICE PLANTS

Wounding of one leaf of young rice plants caused a strong and transien t accumulation of non-conjugated (-)-JA, followed by induction of a nu mber of pathogenesis-related genes, in the treated leaf. The non-treat ed leaf of wounded plants that emerged after the treatment was more re sistant to challenge infection by the rice blast fungus Magnaporthe gr isea (Hebert) Barr. The systemic leaf also showed a transient, but del ayed accumulation of jasmonic acid. Unlike the wounded leaf, there was no accumulation of pathogenesis-related mRNAs or proteins in the syst emically protected leaf. Local application of jasmonic acid, the putat ive signal of the wound response, resulted in a similar degree of syst emic disease resistance as wounding. The results suggest the operation of systemic, wound-related signalling processes in rice that induce s ystemic disease resistance.