Real Time PCR (qRT-PCR) analysis of individual genotypes gene expression. The y axis refers to the relative expression ratio between target mRNA versus the reference mRNA (polyubiquitin SCCCST2001G02.g). The relative expression levels were determined in Internode 1, 5 and 9 tissues from six individuals with the highest Brix measures (CTC98-241, CTC98-242, CTC98-243, CTC98-244, CTC98-246 and CTC98-253) and six individuals with the lowest Brix measures (CTC98-261, CTC98-262, CTC98-265, CTC98-272, CTC98-277 and CTC98-279) of Population 2. All reactions were carried out in parallel and each reaction was performed in triplicates. Error bars were calculated as described previously . The transcript levels for the reference genes were verified to not vary in response to the treatments. The significance of differential gene expression was determined considering normal distributions for each tested condition and comparing them to the average expression for all samples (dotted line). The values of P correspond to the probability Pr (GenotypeX>average) and Pr (GenotypeX<average) for up- and down-regulated genes. P values were calculated for each genotype independently. The SAS was considered differentially expressed when P ≥ 0.95.