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ARS Home » Plains Area » Fargo, North Dakota » Edward T. Schafer Agricultural Research Center » Small Grain and Food Crops Quality Research » Research » Publications at this Location » Publication #409330

Research Project: Identification and Characterization of Quality Parameters for Enhancement of Marketability of Hard Spring Wheat, Durum, and Oat

Location: Small Grain and Food Crops Quality Research

Title: Modulation of seed amylose content in durum wheat through mutagenesis of starch synthase IIa (SSIIa) and its effect on milling and semolina quality

item HOGG, A.C. - Montana State University
item Dykes, Linda
item OIESTAD, A. - Montana State University
item GIROUX, MJ. - Montana State University

Submitted to: Journal of Cereal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/21/2023
Publication Date: 11/30/2023
Citation: Hogg, A., Dykes, L., Oiestad, A., Giroux, M. 2023. Modulation of seed amylose content in durum wheat through mutagenesis of starch synthase IIa (SSIIa) and its effect on milling and semolina quality. Journal of Cereal Science. 115:103816.

Interpretive Summary: Wheat seeds are made up of 70% starch in a 3:1 ratio of amylopectin to amylose. Durum wheat with a higher proportion of amylose has a positive impact on pasta firmness and nutrition but has a significant negative impact on total starch content that leads to decreases in seed yield, seed weight, and semolina flour yield, which are all undesirable. One of the enzymes that plays a role in producing amylose in wheat is Starch Synthase IIa (SSIIa). In this study, durum wheat lines with modified SSIIa were created to contain different levels of amylose. Durum wheat lines with more than 34% amylose increases had lower starch content, which resulted in decreased seed weight and semolina yield, and the semolina flour end-use quality was undesirable. However, two durum wheat lines were discovered that contained amylose increases of ~34% that neither reduced seed size or starch content, and the semolina flour end-use quality was desirable. Further examination of these two lines is warranted to measure the impact they may have on pasta quality, specifically pasta firmness and nutrition.

Technical Abstract: The elimination of Starch Synthase IIa (SSIIa) in durum wheat seeds increases seed amylose and protein content but decreases seed starch and seed size. To mitigate the negative impact of increased amylose upon seed size we identified partially functional SSIIa alleles that were combined with SSIIa null alleles. The first step was to mutagenize durum populations with ethyl methanesulfonate (EMS) and select SSIIa-A1 and SSIIa-B1 missense mutation containing alleles and combine them by crossing with SSIIa null alleles. Segregating lines possessing a SSIIa null mutation in one genome and a missense mutation in the other genome were compared to single SSIIa null mutant sister lines and controls over two field seasons. Harvested grain was analyzed for yield, protein, physical seed parameters, starch properties, and milling performance. Lines that carried one SSIIa null and one missense allele showed elevated amylose content across both years compared to single null sister lines and controls. In most SSIIa haplotypes tested, increased amylose content was negatively correlated with seed size, seed starch content, peak RVA, falling number, flour swelling power, and semolina yield. However, two SSIIa missense alleles were identified that increased amylose to 34 % when combined with a SSIIa null allele. Thus, moderate amylose increases are possible if a small amount of SSIIa activity remains in developing wheat seeds without negatively impacting seed size or starch content.