Variation in sorghum starch synthesis genes associated with differences in starch phenotype

The properties of sorghum starch may influence digestibility and nutritional value in animal and human diets and the processing performance of starch in industrial applications. The variation in grain composition and starch physiochemical properties was evaluated. The DNA sequence of three starch synthesis genes was surveyed and an association approach used to investigate the genetic basis of phenotypic differences in sorghum. Single nucleotide polymorphisms (SNPs) in SSIIa distinguish three haplotypes that were associated with significant differences in gelatinisation temperature and thousand-kernel weight. SSIIa haplotype (H1) accessions had a significantly lower mean gelatinisation temperature of 80.5 °C compared to 87.6 °C and 91.5 °C for H2 and H3, respectively. Polymorphisms in SBEIIb were associated with a 12 °C difference in gelatinisation temperature and GBSSI polymorphisms with total starch content. The SNPs identified provide a genetic explanation for variation in starch properties in sorghum.