GENETIC CHARACTERIZATION OF OCTOPLOID (AABBDDRR) AND HEXAPLOID (AABBRR) TRITICALES

Abstract

The genetic variability analysis of octoploid and hexaploid triticales, evidenced by the RAPD-PCR method has allowed the triticales’ (hybrids) differentiation in terms of their ploidy levels corresponding to their primary or secondary nature. The molecular genetic distances derived from Dice’s similarity coefficients are based on 84 RAPD markers of which 40 bands are polymorphic (47.61%). The analysis of the matrix shows that the Sørensen–Dice’s indices of similarity vary between 1 and 0 with an average of 0.52. The dendrogram shows a segregation of three groups: The first group is consists of triticales 8x ([Mahon-demias/ Merced], [KVZ/alb/RC9] and [Mahon-demias/RC9]). The second group is constituted of triticales 6x (LAMB 2 and CHREA) and the third group encloses only FAHAD 6x triticale. It clearly exposed an intraspecific variability (i = 0;i = 0.81; i = 1) and also, the presence an intervarietal polymorphism in the hexaploid group (i=0, i=0,12, i=1) . The latter produced a high number of specific RAPDs (16) whereas the octoploid triticales amplified a lower number (2). This result confirmed that the specific markers (RAPD) are conversely proportional to the ploidy levels. The triticale (FAHAD5) could be a choice material and could be used as a gene donor for the accession of hybrid triticales. Despite the genomic kinship, the important genetic distance between octoploids (AABBDDRR) (D<10) and hexaploids (AABBRR) (D>15) was revealed in this study. This is explained by a genetic differentiation between to the ploidy level.