Fig. 4. Effect of spray or soil drench application of hexanoic acid (Hx) and acibenzolar-
S-methyl (ASM) at 20 days after first and second inoculation (4 and 9 weeks after
treatment respectively) on (a) callose accumulation (Readings were calculated from
the average number of blue pixels in the images), (b) CALS1 gene expression relative to
actin and 18S gene expression of in sweet orange leaves inoculated with Xanthomonas
citri subsp. citri at 104 cfu mL1 in the greenhouse assay. Values represent the average
of three experiments, bars represent standard error of the mean values, and different
letters represent significant differences in each time point at P 0.05 according to LSD
test. Relative expression lower than 2 (without letter) is considered not differential
expression.