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Creation of a high-amylose durum wheat through mutagenesis of starch synthase II (SSIIa)
- A.C. Hogg, K. Gause, P. Hofer, J.M. Martin, R.A. Graybosch, L.E. Hansen, M.J. Giroux
- Journal of cereal science 2013 v.57 no.3 pp. 377-383
- amylopectin, amylose, durum wheat, firmness, gene expression, genes, glycemic index, missense mutation, mutagenesis, pasta, progeny, screening, seeds, starch granules, starch synthase, transgenic plants, value added
- In cereal seeds, mutations in one or more starch synthases lead to decreased amylopectin and increased amylose content. Here, the impact of starch synthase IIa (SSIIa or SGP-1) mutations upon durum starch was investigated. A screen of durum accessions identified two lines lacking SGP-A1, the A genome copy of SGP-1. The two lines were determined to carry a 29 bp deletion in the first exon of SSIIa. The SGP-A1 nulls were crossed with the durum variety ‘Mountrail’ and F5 derived SGP-A1 null progeny lines were treated with EMS. From each EMS population, one SGP-B1 null mutation was recovered with each being a missense mutation. Each of the SGP-1 nulls was found to have large increases in amylose content and reduced binding of SGP-2 and SGP-3 to the interior of starch granules. RNA-Seq was used to examine the impact the loss of SGP-1 has upon other starch biosynthetic genes. Significant increases in transcript levels of several starch biosynthetic genes were observed in SGP-1 nulls relative to Mountrail. The resultant high amylose durums may prove useful in the creation of value added pasta with increased firmness and reduced glycemic index.