Fig. 3.

Expression of genes encoding enzymes involved in citrate metabolism in common bean genotypes ‘Quimbaya’ (Al-resistant) and ‘VAX 1’ (Al-sensitive) grown in nutrient solution treated with or without 20 µm Al for 4 h. Total RNA was extracted from root tips. Quantitative RT-PCR was performed using the β-tubulin gene as internal standard and untreated plants of the Al-resistant genotype ‘Quimbaya’ as calibrator. Relative gene expression was calculated from three biological and two technical replicates; standard errors are shown.