For enzyme activity assay, 10 g of sarcocarp samples around the
infection spots from 15 fruits were ground in mortar using liquid
nitrogen. All the enzymes were extracted at 4 C and the absorbance
was determined by UV-160 spectrophotometer (Shimadzu,
Japan). The activity of phenylalanine ammonia-lyase (PAL) was
detected following the methods of Yao and Tian (2005).