Résumé:
The study of genetic diversity in a collection of the allotetraploid species Aegilops geniculata Roth(UM) collected in Algeria was assessed using morphological, biochemical and molecular approaches.
This was carried on a wide sampling following a climatic gradient throughout North Algeria. This estimation was preceded by assessing the genetic variability of the diploid progenitors of the tetraploid species (Ae. comosa and Ae. umbellulata) based on gluten proteins. For diploids, a significant variation
was revealed for the three classes of gluten proteins. Several new alleles corresponding to HMW-GS were identified and a nomenclature was proposed as: 8 alleles were found at the Glu-M1 locus (with 5 new alleles) and 3 alleles (with one new) at the Glu-U1 locus. For LMW-GS (B- zone), 14 and 7 alleles were revealed at Glu-M3 and Glu-U3 loci respectively. For gliadins, a typology was established.
Morphological diversity of Ae. geniculata was estimated using 15 descriptors. Individuals were morphologically homogenous and little differences were found between accessions. Results of PCA reveal that traits expressing the wide of the spike distinguished better between accessions. Biochemical analysis of glutenins showed a high level of polymorphism as; 15 alleles were recognized at the GluM1 locus and 12 at the Glu-U1 locus with a new subunit and several new alleles. For B-LMW-GS,
the locus Glu-M3 expressed 28 alleles and the locus Glu-U3 expressed 25 alleles. Thirty-two specific patterns were revealed for C-LMW-GS. With respect to gliadins, 61 polymorphic bands resulting in 35 gliadin blocks were found. The genetic diversity index indicated that ω-gliadins were the most polymorphic, followed by γ- and β-gliadin then α-gliadins. Molecular data based on RAPD showed a high polymorphism as 145 fragments were detected with a level of polymorphism of 79.31%.
The three studied approaches (morphology, proteins and DNA polymorphism) showed relationships between genetic variation of the accessions and ecogeographic conditions. Correlation between morphology and some climatic factors showed that some independent characters were correlated with the winter minimum temperature. The polymorphism detected in gliadins highlighted a strong correlation between ecogeographic parameters and some ω-gliadin bands especially the band B14.
RAPD polymorphism showed a strong correlation with ecological parameters."
