Attempts have been made to predict Chopin alveograph or French bread-making tests, using tree-based models and PLS regressions. Data came from three sets of trials, involving 130, 214 and 103 different genotypes, which were described for HMW-GS, LMW-GS and small-scale tests currently used in breeding programs. Segmentation trees and PLS regressions indicated that HMW-GS and LMW-GS were not sufficient to explain alone the variability of bread wheat quality. This could be partly due to “allele × environment” and “locus × locus” interactions. For HMW-GS, Glu-B1 was the predominant locus for alveograph and French bread-baking, and some differences in the alleles hierarchy were demonstrated according to the end-use parameter considered. For LMW-GS, Glu-B3 seemed to be preponderant, with alleles b′, c and g being favourable and allele c′ unfavourable. Joint use of the information brought by glutenin subunits and technological tests did not enable to predict satisfactorily, neither the different parameters of French bread-baking, nor the extensibility L of alveograph. Only the prediction of the strength W proved reliable, and robust PLS equations were proposed for this alveograph parameter. These prediction equations could be of interest to select for high values of W in the mid generations of breeding

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The polymers of wheat glutenins are studied here using asymmetric flow field flow fractionation (A4F). Molecular mass (Mw), gyration radius (Rw), and the polydispersity index (PI) of polymers were measured over a four-year, multi-local wheat trial in France. The experiment, involving 11 locations and 192 cultivars, offered the opportunity to approach the genetic and environmental factors associated with the phenotypic values of the polymer characteristics. These characteristics, which were all highly influenced by environmental factors, exhibited low broad-sense heritability coefficients and were not influenced by grain protein content and grain hardness. The 31 alleles encoding the glutenin subunits explained only 17.1, 25.4, and 16.8% of the phenotypic values of Mw, Rw, and PI, respectively. The climatic data revealed that a 3.5 °C increase between locations of the daily average temperature, during the last month of the grain development, caused an increase of more than 189%, 242%, and 434% of the Mw, Rw, and PI, respectively. These findings have to be considered in regard to possible consequences of global warming and health concerns assigned to gluten. It is suggested that the molecular characteristics of glutenins be measured today, especially for research addressing non-celiac gluten sensitivity (NCGS).

Analysis of Portuguese wheat (Triticum aestivum L.) landrace ‘Barbela’ revealed the existence of a new x-type high molecular weight-glutenin subunit (HMW-GS) encoded at the Glu-A1 locus, which we named 1Ax1.1. Using one-dimensional and two-dimensional electrophoresis and mass spectrometry, we compared subunit 1Ax1.1 with other subunits encoded at the Glu-A1 locus. Subunit 1Ax1.1 has a theoretical molecular weight of 93,648 Da (or 91,508 Da for the mature protein) and an isoelectric point (pI) of about 5.7, making it the largest and most acidic HMW-GS known to be encoded at Glu-A1. Specific primers were designed to amplify and sequence 2601 bp of the Glu-A1 locus from the ‘Barbela 28’ wheat genome. A very high level of identity was found between the sequence encoding 1Ax1.1 and those encoding other alleles of the locus. The major difference found was an insertion of 36 amino acids in the central repetitive domain.

Putting together information on French bread-baking drawn from 15 years of multi-local experimentation and results of various technological tests (protein content and grain hardness, Pelshenke test, Zeleny sedimentation test and Chopin alveograph), has made it possible to study the effects of genotype and environment on the traits tested as well as the relationships between them. With the exception of protein content and extensibility L of alveograph, genotype x environment interactions are weak for technological tests, whereas Cnerna bread-baking parameters are strongly influenced by these same interactions. There would appear to be a relatively close connection between the technological tests (except for protein content and extensibility L of alveograph). The technological tests are, however, at best quite weakly linked to bread-baking parameters, making indirect selection quite unreliable. Threshold values making it possible to eliminate only those genotypes showing little chance of high bread-baking quality are defined for the technological tests. In other respects, it seems that grain hardness has no influence on French bread-baking quality. Knowledge of hardness only seems interesting in helping interpret tests at constant hydration, such as Chopin alveograph, in which it introduces bias. (© 1999 Inra/Editions scientifiques et médicales Elsevier SAS. French bread-baking / alveograph / Zeleny / Pelshenke / hardness / interaction Résumé-Une étude sur la fiabilité de la sélection indirecte pour la valeur en panification française chez le blé tendre. La récapitulation, sur 15 années d'expérimentations multilocales, de données relatives à la panification française et à différents tests technologiques (teneur en protéines et dureté du grain, test Pelshenke, test de sédimentation de Zeleny et alvéographe Chopin), nous a permis d'étudier les effets du génotype et du milieu sur ces caractères et Communicated by Max Rives (Villeneuves-lès-Avignon, France)

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Using asymmetric flow field flow fractionation, the polymer mass (Mw), gyration radius (Rw) and the polydispersity index (PI) of glutenin polymers (GPs) have been previously studied. Here, using the same multi-location trials (4 years, 11 locations and 192 cultivars), the factors associated with the conformation (Conf) of the polymers were reported. Conf, which is the slope of Log (Rw) = f [Log (Mw)], varied between 0.285 and 0.740. Conf had low broad-sense heritability (H 2 = 16.8) and was significantly influenced by temperature occurring over the last month of grain filling. Higher temperatures were found to increase Rw and the compactness and sphericity of GPs. The HMW-GS and LMW-GS alleles had a significant influence on the Conf value. Assuming a Gaussian distribution for Mw, the number of polymers present in wheat grain was computed for different kernel weights and protein concentrations: it exceeded 10 12 GPs per grain. Using atomic force microscopy and cryo-microscopy, photos of GPs were revealed for the first time. Under high temperatures, GPs became larger, less reticulated, more spherical and consequently less prone to rapid hydrolysis. Some orientations aimed at reducing the possible impact of the numerous GPs for people suffering from non-celiac gluten sensitivity (NCGS) were proposed.