title: Induced mutations in thestarch branching enzyme II(SBEII) genes increase amylose and resistant starch content in durum wheat.
abstract: Starch is the largest component of the wheat (Triticum aestivumL.) 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 thestarch branching enzyme II(SBEII) 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 theSBEIIa-A andSBEIIa-B homoeologs in the tetraploid durum wheat variety Kronos (T. turgidumssp.durumL.). Single-gene mutants showed non-significant increases in amylose and resistant starch content, but a double mutant combining aSBEIIa-A knock-out mutation with aSBEIIa-B splice-site mutation showed a 22% increase in amylose content (P<0.0001) and a 115% increase in resistant starch content (P<0.0001). In addition, we obtained mutants for the A and B genome copies of the paralogousSBEIIbgene, mapped them 1-2 cM fromSBEIIa, and generated doubleSBEIIa-SBEIIbmutants to study the effect of theSBEIIbgene in the absence ofSBEIIa. These mutants are available to those interested in increasing amylose content and resistant starch in durum wheat.
authors.affiliation: Dept. of Plant Sciences, University of California, Davis, CA 95616, USA.
authors.forename: Brittany
authors.initials: B
authors.lastname: Hazard
authors.affiliation: Dept. of Plant Sciences, University of California, Davis, CA 95616, USA.
authors.forename: Xiaoqin
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Dept. of Plant Sciences, University of California, Davis, CA 95616, USA.
authors.forename: Pasqualina
authors.initials: P
authors.lastname: Colasuonno
authors.affiliation: Dept. of Plant Sciences, University of California, Davis, CA 95616, USA.
authors.forename: Cristobal
authors.initials: C
authors.lastname: Uauy
authors.affiliation: Dept. of Plant Sciences, University of California, Davis, CA 95616, USA.
authors.forename: Diane M
authors.initials: DM
authors.lastname: Beckles
authors.affiliation: Dept. of Plant Sciences, University of California, Davis, CA 95616, USA.
authors.forename: Jorge
authors.initials: J
authors.lastname: Dubcovsky