Abstract only

In order to estimate the dependence of variability in the number of chromosomes on anomalies occurring in the course of mitotic division of cell cultures in vitro, the mitotic and meiotic processes of regenerant Triticum durum plants were studied. To induce callusogeny from immature genns, the nutrient medium M-S with 2.4-D (4 mg/l) was used. The reconstruction of plants was carried out on the medium L-S containing IAA (0.5 mg/l). A study of the number of chromosomes in roots of the F o generation plants showed that variability made approximately 17% of the analyzed cells. Hypo- and hyper-aneuploids were found. Deviations in the course of mitotic divisions were observed, such as: a non-uniform divergence of chromosomes, restitution and conglutination. The cytogenetic analysis of meiosis in anthers Of the F o generation plants showed deviations in the course of meiotic division. The initial stages of meiosis proceeded with insignificant distortions, however in the anaphase I and II significant distortions in the divergence of chromosomes occured: single bridges, fragments of chromosomes, numerous micronuclei in dyads and tetrads, and a great number of stuck chromosomes between polarized chromosomes were observed. A comparison with the check (having not passed the stage of cultivation in vitro) showed that the percentage of abnormal cells in the control for Al, All and tetradogenesis was equal to 8, 9 and 13% respectively. In the regenerant plants, these parameters were much higher, -75.7, 70.4 and 78.5%, respectively. The distortions affected fertility of the regenerant plants, which made 36% against the check plants, were fertility was as high as 98%. The analysis of meiosis in anthers of the regenerant plants of F1 generation produced from seeds ofF o plants under field conditions evidenced some stabilization established in the course of meiotic division. Thus, in F I plants the distortions generally manifested themselves in the sticking of chromosomes, which were observed mostly at metaphase I. The number of micronuclei found in dyads and tetrads considerably decreased (Table ). The fertility of seeds of F1 regenerant plants was a little higher than in Fo plants. However, the seeds were weak and wrinkled. According to their growth rate, the plants of Fo and F1 generations lagged behind the checks. The carried out studies showed a tendency to reparation processes in F1 generation, with a high percentage of anomalies in metaphase I. Pheno- typically, the plants of F o and F1 generations did not differ from each other. A research in the variability preservation analysis in F2 and F3 generations is under way.

English

0408|AGRIS 0401|AL-Wheat Program

Juan Carlos Mendieta

CIMMYT Publications Collection