Induced mutations in the () genes increase amylose and resistant starch content in durum wheat.

Starch is the largest component of the wheat ( L.) grain and consists of approximately 70-80% amylopectin and 20-30% amylose. Amylopectin is a highly-branched, readily digested polysaccharide, whereas amylose has few branches and forms complexes that resist digestion and mimic dietary fiber (resistant starch). Down-regulation of the () gene by RNA interference (RNAi) was previously shown to increase amylose content in both hexaploid and tetraploid wheat. We generated ethyl methane sulphonate (EMS) mutants for the -A and -B homoeologs in the tetraploid durum wheat variety Kronos ( ssp. L.). Single-gene mutants showed non-significant increases in amylose and resistant starch content, but a double mutant combining a -A knock-out mutation with a -B splice-site mutation showed a 22% increase in amylose content (<0.0001) and a 115% increase in resistant starch content (<0.0001). In addition, we obtained mutants for the A and B genome copies of the paralogous gene, mapped them 1-2 cM from , and generated double mutants to study the effect of the gene in the absence of . These mutants are available to those interested in increasing amylose content and resistant starch in durum wheat.