CAPS marker assisted selection of Genotypes I, II and III based on (T/A) single nucleotide substitution polymorphism. The nucleotide substitution T/A in the EcoRV cut site are shown in red. (A). PCR produces only the A allele (in blue) in Genotype I, only the T allele (in green) in Genotype III, but produces both the T and A alleles in Genotype II. The T allele has EcoRV cut site (GATATC) but not the A allele. (B). The T allele in Genotype II or Genotype III gives rise to two fragments of size 330 bps and 350 bps after EcoRV restriction digestion. (C). Gel electrophoresis of EcoRV restriction digested products, therefore, produces one band in Genotype I (PCR fragment not cut, 680 bps), two bands in Genotype III (PCR fragment cut into 330 and 350 bps) and three bands in Genotype II (one PCR fragment not cut 680 bps, other fragment cut into two, 330 and 350 bps fragments).