Synthetic amphiploid production from the crosses between some bread wheat cultivars and Aegilops triuncialis L

Aegilops triuncialis L. (2n=4x=28; CtCtUtUt) is one of the tetraploid Aegilops species harboring valuable genes for resistance to many biotic and abiotic stresses. In the present study the bread wheat cultivars MV17، Navid، Omid، Pishgam، Zarin were crossed with an accession of Ae. triuncialis and the resulted F1 and F2 (obtained by the selfing of F1 plants) hybrids studied using the conventional cytogenetic methods. The crossability (seed set per pollinated floret) of whet cultivars was significantly different with an average of 46. 24 percent. Chromosome counting confirmed the presence of 35 (n=5x=35; ABDUtCt) chromosomes in a sample of F1 seeds. The mean frequency of F2 seeds (per floret) was 3. 54 percent. The F2 seeds fell in two distinct classes of shrank and smooth seeds. Chromosome counting in root tip cells revealed 40-70 chromosomes in a sample of F2 seeds، indicating the ocurance spontaneous amphiploid (2n=10x=70; AABBDDUtUtCtCt) formation in F2 generation. Induced polyploidy using colchicine was also successful in one of the treated F1 seeds، producing 70 chromosome seeds. Study of the metaphase I of the meiosis in F1 hybrids on average revealed 7 rod bivalents and 21 univalents in each Pollen Mother Cell (PMC). F1 seeds generally matured 30 days later than that of their wheat parents. The frequency of BC1F1 seeds resulting from crossing of F1 with the wheat parent was about 1. 27 percent which was lower than F2 seed frequency.