Cytogenetic Studies of some Iranian Wild Wheat Species (Aegilops) and OR Banding



In order to deliberate karyologic and cytogenetic parameters, fifteen Aegilops populations, collected from different regions of the country, were studied. These populations included 3 diploids of Ae. tauschii, 6 tetraploids of either Ae. triuncialis or Ae. cylindrica species. The resultant data were analyzed according to a 2-factorial experiment on the basis of a completely randomized design (CRD) with 5 replicates of cells. The factors considered were populations (3 and 12 levels) and chromosome (7 and 14 levels) for diploids and tetraploids, correspondingly. The ANOVA results indicated conspicuous between-diploid differences for L, S, TL and r-value, between-tetraploid differences for RL%, and between-chromosomes either diploid or tetraploid differences for L, S, TL, RL% and F%. Mean comparisons were carried out, using LSR test. Both type populations differed in satellite number, ranging from 0 to 2 pairs. The most chromatin length was detected in pop. 11 (152.18 µm), while pop. 2 bore the least (70.52 µm). Among 15-population karyotypes, 10 were determined in 1A class of Stebbin's classification vs. 5 in 1B class. According to Levan's chromosome nomenclature, the chromosomes of 5 pops. were identified as medium region " m " and those of 10 pops. as both medium region " m " and sub medium region " sm ". Chromosome banding has proven to be a valuable tool for karyotype analysis and for rapid detection of gross chromosomal rearrangements, including large deletion and insertion mutation as well as transpositions. This research was carried out towards an establishment of a procedure, OR-banding, for the detection of the Aegilops chromosomes. Chromosomes OR-banding technique was investigated on 3 Iranian pops. of Ag. tauschii. Chromosome slides were prepared via squash technique in different intervals (24 h to one week) after being slained with 1% aceto-orcein dye. Chromosomal banding pattern was observed 3 d after staining. It was shown that the number of the bands decreased from prophase to metaphase stages of mitosis. The best time for observation of the OR-Banding pattern in Aegilops samples was a long-term (one week) past remaining of the root meristems in dye. This method can be empolyed for an identification of metaphase chromosomes in wild relatives of wheat.