Effects of the Gpc‐B1 locus on high grain protein content introgressed into Argentinean wheat germplasm

Abstract

Wheat grain protein content (GPC) is important for human nutrition and has a strong influence on the quality of pasta and bread. The objective of this study was to analyse the introduction of the Gpc-B1 allele into two Argentinean bread wheat cultivars. Near-isogenic lines were developed in 'ProINTA Oasis' and 'ProINTA Granar' using marker-assisted selection. Gpc-B1 lines showed a significant (P = 0.01) increase in GPC and a significant (P = 0.001) decrease in grain weight in comparison with control lines without Gpc-B1. Differences in yield were not significant (P = 0.49) between lines. Gpc-B1 lines significantly reduced (P = 0.02) straw nitrogen concentration at maturity and significantly increased (P = 0.02) the nitrogen harvest index. When data were analysed by genotype and environment, differences in some analysed parameters were found, indicating that Gpc-B1 expression may be affected by different genetic backgrounds and environmental conditions. These results suggest that the introgression of the Gpc-B1 allele into Argentinean wheat germplasm could be a valuable resource for improving GPC with no detrimental effect on grain yield.

Detection of NAM-A1 Natural Variants in Bread Wheat Reveals Differences in Haplotype Distribution between a Worldwide Core Collection and European Elite Germplasm

“…Therefore, results presented in Table 2 should be interpreted with caution. Nevertheless, in agreement with the described mean values, several studies analyzing the introgression of the functional allele of Gpc-B1 in different spring hexaploid wheat [9,11,12] concluded that NAM-A1 homoeolog increased GPC and decreased TKW. However, other studies such as Waters et al [20] showed no effect on TKW.…”

“…An improved N remobilization (%N_S and NHI) was also assessed [9]. However, the effect of Gpc-B1 on grain yield across genotypes and environments was not significant [9,11,12] even if it was strongly affected by the genetic background [9]. Similarly, study of mutants concluded that functional NAM-A1 (6A) and NAM-B2 (2B) genes accelerate senescence and increase GPC with a larger phenotypic effect for NAM-A1 than NAM-B2 [4,8].…”

“…Nevertheless, hexaploid wheats have five other NAM genes, three paralogous (on chromosomes 2A, 2B and 2D) and two homoeologous (on chromosomes 6A and 6D) of which NAM-A1 (6A) has the same role as NAM-B1 [4,8]. Most studies on NAM wheat genes used mutants [4,8], near isogenic lines [9][10][11][12] or RNAi lines [3,4] and few studies have focused on the cultivated diversity [6,13]. This paper aims to characterize natural variants of NAM-A1 in hexaploid bread wheat and to hypothesize on the biological mechanisms explaining their effects.…”

Functional characterization of GPC-1 genes in hexaploid wheat

“…We currently do not know if this was a result of unfavorable environmental conditions during the extended stay green period or a finite capacity of the grains of the tested variety to increase grain weight beyond a certain limit. Common wheat plants containing the wild emmer GPC-B1 segment showed higher GPC with no yield penalties (Mesfin et al 1999;Kumar et al 2011;Carter et al 2012;Tabbita et al 2013) but under certain conditions a negative effect has been shown on TKW Carter et al 2012;Tabbita et al 2013). Kernel weight is also under tight genetic control, with large variability among wheat varieties (Gegas et al 2010).…”

The stay-green phenotype of TaNAM-RNAi wheat plants is associated with maintenance of chloroplast structure and high enzymatic antioxidant activity

“…Early efforts in this crop uncovered the existence of a high grain protein content (GPC) trait derived from a wild emmer wheat accession located in the short arm of chromosome 6B (Joppa et al, 1997). The corresponding allele, when introgressed into modern hexaploid wheat cultivars, leads to enhanced protein content which in some cases has been accompanied by detrimental effects on grain size (Brevis and Dubcovsky 2010;Tabbita et al, 2013). With the exception of some spring swedish varieties which possess a rare allele of GPC (Asplund et al, 2013), most modern Triticum aestivum cultivars do not possess a functional version due to a frame shift mutation in the coding region of the gene (Uauy et al, 2006).…”