Abstract
The time-course changes of enzyme activities of phenylalanine ammonia-lyase (PAL) and tyrosine ammonialyase (TAL) in young rice panicles inoculated with blast fungus (Pyricularia grisea) were examined during a five day period after inoculation and compared with those of uninoculated controls. Four rice materials (two cultivars and two F8-lines selected for blast resistance showing differences in the resistance to blast disease) were used for the experiment. The activities of PAL and TAL one or two days after inoculation increased in the inoculated as well as in the control panicles and reached maximum values within two or three days. The increase of the ratios and levels of the activities of PAL and TAL in the inoculated samples were much higher than those of the uninoculated controls. TAL activity was considerably lower than the PAL activity and the time required for reaching the maximum activity in 7F8-8 and Reiho was delayed by one day compared with the PAL activity. Both the ratios and levels of increased activity of PAL and TAL were significantly different among the four rice cultivars harbouring different blast resistance genes. The detailed relations between the different activities of PAL and TAL and individual blast resistance gene actions remain to be clarified.
