Abstract:
Enzyme activity involved in anthracnose disease resistance, Peroxidase (POD), Phenylalanine
ammonia lyase (PAL), ?-1,3-glucanase (GLU) and Chitinase (CHI) was investigated in chili fruit
var. Jinda (resistance) and var. Bangchang (susceptible) after artificial inoculated with Colletotrichum
gloeosporioide, causal anthracnose disease for 6 hour. The results showed that GLU and CHI activity
significantly increased in var. Jinda after infection but no increased in POD and PAL activity.
Pathogen inoculation of Bangchang chili found the increase of POD activity only. This implies that
GLU and CHI activity may indicate the resistant variety of chili on anthracnose disease after
artificial inoculation. The effect of chitosan solution on controlling of anthracnose disease and
physiology of Jinda chili was conducted by wound-inoculation with C. gloeosporioides and followed
coating with chitosan solution at concentrations of 1.2% and 1.6%. It was revealed that 1.6% chitosan
coating gave the better result to delay the disease incidence and maintain the fruit firmness than 1.2%
chitosan coating. However 1.6% chitosan coating caused fruit fermentation. Chitosan coating at 1.2%
retarded the respiration rate and ethylene production but could not delay weight loss, L and a value of fruit,
and L and b value of stem-end. The effect of chitosan solution at the concentration of 1.2% on the induction
of POD, PAL, GLU and CHI activity was obtained in chili fruit var. Jinda after wound-inoculation with
C. gloeosporioides for 6, 12, 18, 24, 36 and 48 hrs. Chitosan coating had no effect to stimulate the activities
of POD, PAL, GLU and CHI. However the activity of POD, GLU and CHI was induced by wound and
inoculation.