Analysis of duplication in the Spanish durum wheat collection maintained in the CRF-INIA on the basis of agro-morphological traits and gliadin proteins

A total of 106 potential duplicate cases involved 277 accessions were detected on the basis of passport data in the durum wheat collection maintained in the CRF-INIA. Similarity between accessions was measured by agro-morphological traits. The 90% of the agro-morphological duplication were verified with gliadin proteins, allowing identification of similar material with greater refinement than agro-morphological data. However, the results indicated not to decide for rationalisation only on the basis of molecular data

Temporal trends in the diversity of durum wheat varieties grown in Spain based on gliadin alleles

Gliadin alleles are inherited co-dominantly, they have revealed large levels of inter-varietal polymorphism and identification of a genotype is possible immediately by the electrophoretic protein phenotype. The gliadin loci control the synthesis of a group of proteins named as blocks of gliadins. The main Gli loci are located on the chromosomes of the first (Gli-1) and sixth (Gli-2) homoeologous groups. Alleles at each locus differin number and electrophoretic mobility of encoded gliadins. This ensures a great diversity of the A-PAGE patterns and, therefore, provides a great possibility to distinguish a high number of wheat genotypes and to describe them in terms of gliadin allele composition (Fig.1). Comparative analysis of gliadin markers indifferent groups of wheats (old and new varieties, several samples of a cultivar…) may reveal genetic erosion, different types of selection and loss of genetic identity

Diversity and Genetic structure of the Spanish collection of durum wheat (Triticum turgidum L) landraces

The objectives of this study were to assess diversity and genetic structure of a collection of Spanish durum wheat (Triticum turgidum L) landraces, using SSRs, DArTs and gliadin-markers, and to correlate the distribution of diversity with geographic and climatic features, as well as agro-morphological traits. A high level of diversity was detected in the genotypes analyzed, which were separated into nine populations with a moderate to great genetic divergence among them. The three subspecies taxa, dicoccon, turgidum and durum, present in the collection, largely determined the clustering of the populations. Genotype variation was lower in dicoccon (one major population) and turgidum (two major populations) than in durum (five major populations). Genetic differentiation by the agro-ecological zone of origin was greater in dicoccon and turgidum than in durum. DArT markers revealed two geographic substructures, east-west for dicoccon and northeast-southwest for turgidum. The ssp. durum had a more complex structure, consisting of seven populations with high intra-population variation. DArT markers allowed the detection of subgroups within some populations, with agro-morphological and gliadin differences, and distinct agro-ecological zones of origin. Two different phylogenetic groups were detected; revealing that some durum populations were more related to ssp. turgidum from northern Spain, while others seem to be more related to durum wheats from North Afric

Genetic redundancy among durum wheat accessions as assessed with SSRs and endosperm proteins

Reducing duplication in ex-situ collections is complicated and requires good quality genetic markers. This study was conducted to assess the value of endosperm proteins and SSRs for validation of potential duplicates and monitoring intra-accession variability. Fifty durum wheat (Triticum turgidum ssp. durum) accessions grouped in 23 potential duplicates, and previously characterised for 30 agro-morphological traits, were analysed for gliadin and high molecular weight glutenin (HMWG) subunit alleles, total protein, and 24 SSRs, covering a wide genome area. Similarity and dissimilarity matrices were generated based on protein and SSRs alleles. For heterogeneous accessions at gliadins the percent pattern homology (PH) between gliadin patterns and the Nei’s coefficient of genetic identity (I) were computed. Eighteen duplicates identical for proteins showed none or less than 3 unshared SSRs alleles. For heterogeneous accessions PH and I values lower than 80 identified clearly off-types with more than 3 SSRs unshared. Only those biotypes differing in no more than one protein-coding locus were confirmed with SSRs. A good concordance among proteins, morphological traits, and SSR were detected. However, the discrepancy in similarity detected in some cases showed that it is advisable to evaluate redundancy through distinct approaches. The analysis in proteins together with SSRs data are very useful to identify duplicates, biotypes, close related genotypes, and contamination

Effects of N fertilisation, year and prolamin alleles on guten quality in durum wheat (Triticum turgidum L. ssp. turgidum) landraces from Spain

A subset of durum wheat Spanish landraces, previously evaluated for yield at low and high nitrogen (N) levels, was analysed for quality, protein content (P) and sodium dodecyl sulphate sedimentation (SDSS) test. The evaluation was carried out at the two N rates and in two years. The influence of prolamin alleles at the Glu-1, Glu-3, Glu-B2 and Gli-1 loci on quality parameters was also studied. The non significant Variety-by-Year or Variety-by-N interactions suggested that year and N affected all the varieties in a similar manner. Year and N effects were larger than variety effect for P, which increased with N. In contrast, variety genotype exhibited a stronger influence on SDSS test, which was not affected by year and fertilizer. Variety effects on P did not reflect the variety differences for SDSS test. A high positive influence of some prolamin alleles on quality parameters was detected, mainly for SDSS values. No correlation between yield and P was detected in the landraces adapted to low N. Based on the results of yield and quality evaluations, four landraces with high yield and high gluten strength were pre-selected for low N production

Analysis of genetic variability in a sample of the durum wheat (Triticum durum Desf.) Spanish collection based on gliadin markers

In this work gliadin proteins were used to analyse the genetic variability in a sample of the durum wheat Spanish collection conserved at the CRF-INIA. In total 38 different alleles were identified at the loci Gli-A1, Gli-A3, Gli-B5, Gli-B1, Gli-A2 and Gli-B2. All the gliadin loci were polymorphic, possessed large genetic diversity and small and large differentiation within and between varieties, respectively. The Gli-A2 and Gli-B2 loci were the most polymorphic, the most fixed within varieties and the most useful to distinguish among varieties. Alternatively, Gli-B1 locus presented the least genetic variability out of the four main loci Gli-A1, Gli-B1, Gli-A2 and Gli-B2. The Gli-B1 alleles coding for the gliadin γ-45, associated with good quality, had an accumulated frequency of 69.7%, showing that the Spanish germplasm could be a good source for breeding quality. The Spanish landraces studied showed new gliadin alleles not catalogued so far. These new alleles might be associated with specific Spanish environment factors. The large number of new alleles identified also indicates that durum wheat Spanish germplasm is rather unique

Genetic variation for glutenin and gliadins associated with quality in durum wheat (Triticum turgidum L. ssp. turgidum) landraces from Spain.

The allelic variation at seven prolamin loci involved in quality has been studied in a set of durum wheat landraces from all the Spanish regions where this crop has been traditionally cultivated. The genetic variability was higher than that found in other germplasm collections. All the loci, except Glu-B2, displayed a genetic variability higher than 0.62, with Glu-3 the most polymorphic. In total, five alleles were studied at Glu-A1, nine at Glu-B1, 15 at Glu-A3, 18 at Glu-B3, two at Glu- B2, and eight at Gli-A1 and Gli-B1. New allelic variants not previously identified in durum wheat were detected. The 30 different genotypes of B low-molecular-weight (B-LMW) glutenin subunits analysed, of which 25 are novel, provide an important source of genetic variability for quality breeding. Protein patterns for convars. durum and turgidum, and for the North and South of Spain were identified for the loci with significant influence on quality. Higher variability was observed in convar. turgidum and in the North zone than in convar. durum and the South, respectively, mainly for the Glu-B1 and Glu-B3. Also, convar. turgidum appeared to be a valuable source for new alleles for the LMW glutenin subunits. Wheats from the South were, however, more diverse for prolamins encoded at Glu-A3 - Se ha estudiado la variación alélica en siete loci de prolaminas relacionados con la calidad en un grupo de variedades locales de trigo duro procedentes de todas las provincias españolas donde se cultivaba tradicionalmente. La variabilidad genética encontrada fue mayor que la observada en otras colecciones de germoplasma. Todos los loci, excepto el Glu-B2, mostraron una variabilidad genética mayor que 0,62, siendo los Glu-3 los más polimórficos. En total se estudiaron cinco alelos en el Glu-A1, nueve en el Glu-B1, 15 en el Glu-A3, 18 en el Glu-B3, dos en el Glu-B2 y ocho en el Gli-A1 y Gli- B1. Se han detectado variantes alélicas nuevas que no se habían identificado antes. Los 30 genotipos diferentes analizados de subunidades B de gluteninas de bajo peso molecular (B-LMW), de los cuales 25 son nuevos, representan una fuente importante de variabilidad genética para la mejora de la calidad. Se identificaron patrones de proteínas para las convars. durum y turgidum, y para el norte y sur de España para los loci con influencia significativa en calidad. En la convar. turgidum y en el norte se observó mayor variabilidad que en la convar. durum y en el sur, respectivamente, principalmente en el Glu-B1 y Glu-B3. Además, la convar. turgidum parece ser una fuente valiosa de nuevos alelos para las subunidades LMW de gluteninas. Sin embargo, los trigos del sur son más diversos para las prolaminas codificadas en el Glu-A3

Use of thermographic imaging to screen for drought-tolerant genotypes in Brachypodium distachyon

Thermal imaging has been used to evaluate the response to drought and warm temperatures in a collection of Brachypodium distachyon lines adapted to varied environmental conditions. Thermographic records were able to separate lines from contrasting rainfall regimes. Genotypes from dryer environments showed warmer leaves under water deficit, which suggested that decreased evapotranspiration was related to a more intense stomatal closure. When irrigated and under high temperature conditions, drought-adapted lines showed cooler leaves than lines from wetter zones. The consistent, inverse thermographic response of lines to water stress and heat validates the reliability of this method to assess drought tolerance in this model cereal. It additionally supports the hypothesis that stomatal-based mechanisms are involved in natural variation for drought tolerance in Brachypodium. The study further suggests that these mechanisms are not constitutive but likely related to a more efficient closing response to avoid dehydration in adapted genotypes. Higher leaf temperature under water deficit seems a dependable criterion of drought tolerance, not only in B. distachyon but also in the main cereal crops and related grasses where thermography can facilitate high-throughput preliminary screening of tolerant materials

Creación de la colección nuclear española de trigo duro

Varios grupos de investigación españoles se han coordinado para crear la colección nuclear española de trigo duro (Triticum turgidum L.). Esta colección estará formada por variedades locales, cultivares antiguos y especies afines conservadas en el CRF-INIA. Como paso previo se han seleccionado 200 entradas que maximizan la variabilidad genética de la colección. Para ello se han recopilado, sistematizado y elaborado los datos geográficos, de caracterización y evaluación disponibles de proyectos anteriores. Las entradas han sido clasificadas en 9 zonas agro-ecológicas y cinco grupos taxonómicos, y elegido en cada provincia aquellas que incluyen mayor variabilidad en altitud y tipo de suelo de la zona de recolección, así como en caracteres agro-morfológicos, bioquímicos y/o moleculares. Posteriormente se ha confirmado que la variabilidad genética estudiada está recogida en las 200 entradas seleccionadas

Variablilidad genética de gliadinas en la colección de trigo duro del CRF-INIA de acuerdo a la taxonomía y la zona agroecológica de origen.

Se ha analizado la variabilidad genética para gliadinas, por grupos taxonómicos y zonas agro-ecológicas, en una muestra de la colección española de trigo duro (Triticum turgidum L.). La diversidad genética total fue alta (Ht=0,80) siendo la variación intra grupos mayor que entre grupos para la ssp. (dicoccon, durum y turgidum) y la zona. Las tres ssp. se separaron claramente, y mostraron alelos únicos para los loci analizados. La ssp. dicoccon mostró la mayor proporción de diferenciación entre zonas, especialmente para el locus Gli-B1. La ssp. turgidum presentó la mayor variabilidad, sobre todo en las variedades del norte y del este del país. La ssp. durum mostró menor variación entre zonas, pero con una separación de la zona norte del resto de las zonas, que se agruparon siguiendo un patrón esteoeste. El mayor número de alelos locales se detectó en las variedades del sur. En las tres ssp. se detectaron diferencias significativas entre zonas para los alelos de gliadinas