Evaluation des ressources phytogénétiques des blés cultivés en Algérie et de leurs apparentés.

Abstract

In the first part of this study, several collections were analyzed in order to appreciate the allelic variation of high and low-molecular-weight (HMW and LMW) glutenin subunits composition: a collection of 59 accessions representing 5 genomes (U, C, M, D, N), collection of 856 accessions of local durum wheat (Triticum durum Desf.) collected in Algeria and divided a priori according to their agronomical and morphological traits in 17 varieties, a collection of thirty accessions of lines sisters coming from the ICARDA, obtained from interspecific crossings between 2 Syrian varieties of durum wheat (Cham and Oum Rabi) and 2 related species (T. dicoccum and T. polonicum) and two other collections of 71 bread wheat and 120 durum wheat germoplasm grown in Algeria. Seed samples were provided for the most part by the International Center for Agricultural Research in the Dry Areas (Alep, Syria). The biochemical analysis was carried out by monodimensionel SDS-PAGE. In Aegilops collection, several new alleles corresponding to HMW subunits were detected and an allelic nomenclature was drawn up in which a total of 16 alleles were exprimed at the locus Glu-U1, 13 at Glu-M1, 9 at Glu-C1, 6 at Glu-N1 and 10 at the Glu-D1 locus. Important variation was found in the collection of botanic durum wheat. Among the 16 alleles identified at the Glu-1 loci, two were new. The first named Glu-B1i1 encoding for two bands located between 17 and 18 which was assigned the nomenclature 171 and 181. The other named Glu-B1e1 codes two bands similar to 20x and 20y but with faster mobility, which were named 20x1-20y1 and were analyzed to determine the number of thiol groups. Three and Seven cysteine residues were found respectively. At Glu-3 and Glu-2 loci, 19 alleles were identified, where the allele named Glu-B3ab (encoding for subunits 2-8-9-13-16) was considered as new. In the collection of related durum wheat, we can count six allelic forms, which two are localised at the locus Glu-A1, it acts of the allele “a” and the allele “c” and four at the locus Glu-B1, they are “a, b, d and i”. While referring to international allelic nomenclature, these alleles code for following proteins: 1, nul, 7, 7+8, 6+8 and 17+18 respectively. Important polymorphism caracterise HMW-GS with a total of 13 alleles identified.The knowledge of these alleles constitutes an important tool for the identification varietal of wheat. Extensive variation has been found in bread and durum wheat germoplasm grown in Algeria. In bread wheat 3, 6 and 5 alleles were observed at Glu-A1, Glu-B1 and Glu-D1 loci encoding HMW-GS respectively. LMW-GS displayed similar polymorphism, as 4, 9 and 3 alleles were identified at loci Glu-A3, Glu-B3 and Glu-D3 respectively. In durum wheat collection, 3 alleles were exprimeted at Glu-A1 locus and 9 at Glu-B1. At Glu-A3, Glu-B3 and Glu-B2 loci 5,8 and 2 alleles were identified. The new HMW and LMW glutenin variation found in this work suggests their possible utilisation in breeding for wheat quality. The aim of the second part of this study was to evaluate the differences due to the culture regimes (biological versus conventional) in composition of total and metabolic proteins in the mature wheat grain. The analyses were carried out on three classes of sizes of grains (small, middle and large) from two varieties of bread wheat: Ataro and Renan. The two varieties exhibited differences on the grain sizes distribution. The one-dimensional electrophoretic analyses of storage and metabolic proteins showed a significant effect of the culture regime on HMW-SG and LMW-SG for the two varieties. Many gliadins (5 bands out of 16 for Renan and 11 out of 22 for Ataro) were influenced by culture regimes. The proteomic approach, carried out on the Ataro variety, revealed for all sizes of grains, 20 variable spots of which three were more expressed in biological regime. Analysis of the proteome between sizes revealed 149 spots quantitatively different from one class to another for the biological regime, against 115 for the conventional regime. In addition to storage proteins, spectrometry analysis using MALDI-TOF and the database interrogations, allowed serpines and proteins involved in the sugars metabolism to be identified.