yield and quality traits

Gluten strength

Contributed by Laura Pfluger (pfluger.laura@inta.gob.ar)

The quality of wheat flour for bread making depends on the viscoelastic properties of the dough, which are influenced by the quantity and quality of the gluten-forming storage proteins of the endosperm.

Grain texture

Contributed by Gabriela Tranquilli (tranquilli.gabriela@inta.gob.ar)

Wheat marketing systems established a primary classification of hexaploid wheat (Triticum aestivum L.) based on endosperm texture, i.e. the hardness or softness of the grain, because this trait determines many of its potential end-uses. Hard textured grains require more grinding energy than soft textured grains to reduce endosperm into flour, and during this milling process a larger number of starch granules become physically damaged.

Starch properties. Waxy mutants

One of the main components of wheat flour is starch, its relative content and chemical composition affect the quality of the products obtained from wheat.

Starch is a glucose polymer composed of two different types of structures: amylose and amylopectin. Amylose is a linear polymer with D-glucosyl units linked by α 1-4 bonds. Amylopectin has a branched structure: it also has α 1-4 bonds but every 20-25 glucosyl there are ramifications due to α 1-6 bonds.

WAPO1. A candidate gene for spikelet number per spike

Achieving higher grain yields is a difficult task due to the number of genes involved, their interactions and the importance of environmental effects. This complexity determines that taken as a single trait, yield shows low heritability. Instead of improving overall yields, a more effective strategy is to focus on yield components, such as grain weight, spikes per unit area, grain number per spikelet and spikelet number per spike (SNS). Among these, SNS is an attractive trait for wheat breeders because it shows a higher heritability compared to the other yield components.

High grain protein content gene Gpc-B1 and stripe rust resistance gene Yr36

Grain protein content (GPC) is one of the most important quality factors for pasta and bread wheats. Breeding for an increase in GPC is difficult because the genetic variation for this character is small compared to variations caused by the environment, besides there is a negative correlation between GPC and grain yield.

Thousand Grain Weight and Grain Size gene TaGW2-A1

The rice Grain Width and Weight 2 (OsGW2) gene was previously described as a negative regulator of grain weight and width. It encodes a RING-type E3 ubiquitin ligase (1). The wheat homolog in wheat is the TaGW2 gene, with homoeologues in the three genomes, although the most closely studied to date is the A genome homoeologue, TaGW2-A1. Two studies showed in Chinese wheat lines a significant association of a single nucleotide polymorphism (SNP) in the promoter region of TaGW2-A1 with thousand grain weight (TGW) and grain width (2, 3).