Display of the exon-intron structure of HaTPS1a ( HaGAS1 ), HaTPS1b ( HaGAS2 ) and HaTPS2 ( HaCS ) genes. Grey boxes represent exon sequences, lines show intron sections. Length of nucleotide sequences is shown for exons in the boxes and for introns above the line. DDxxD marks the position of the conserved aspartate-rich region. i2: intron 2; i4: intron 4.