Validation of differential expression by qRT-PCR. Relative quantification (RQ) of transcripts associated with differential AsA accumulation in IL12-4 and M82 in years 2007 and 2008. Mean values ± SE are shown. An asterisk indicates that differences between IL 12-4 and S. lycopersicum cv. M82 are statistically significant in Student's t test (P < 0.05), and § indicates significant differences in expression between 2007 and 2008 (P < 0.05).