Morphological variability of haploid plants and doubled haploids of rice obtained on one callus line in anther culture in vitro was studied. The work was carried out on rice plants Oryza sativa L. subspecies japonica Kato varietу Cascade. Regenerant plants of one callus line obtained from one rice anther (four in total) were divided into two or three groups of 20-30 plants, depending on the sample size in order of their differentiation on callus and transplantation on the rooting medium. Two callus lines (15.1 and 18.1) formed half of the haploids, half of the doubled haploids, and two other callus lines (5.1 and 7.2) numerous haploids. On callus lines with numerous haploids (5.1 and 7.2), as the regenant number increases, the size of plants decreases (plant height, number of flowers on the main panicle, number of panicles). On the lines 15.1 and 18.1 between groups of haploids and between groups of doubled haploids statistically significant differences absent. In breeding purposes for the induced doubling of the number of chromosomes in haploid regenerants with antitubulin substances such as colchicine, it is advisable to use plants that form on callus among the first. Between haploids of four callus lines and doubled haploids of two callus lines, statistically significant differences (at p=0.001) were revealed using the Hotelling's T2-criterion, calculated for the whole complex of biometric features. Haploids of different lines differed in three or four of them, doubled haploids on three of the five signs (length of panicle, productive bushiness and plant height). Varieties of interest to breeders may be improved by anther culture in vitro.
The work is relevant for understanding evolutionary processes in plant species. Twelve callus lines with multiple regeneration of haploids and doubled haploids were obtained in F1 hybrids of Oryza sativa L. through in vitro androgenesis. Intracallus variability of the morphological features of haploids was often accompanied by a decrease in the values of morphological features with an increase in the serial number (p < 0.05). The number of panicles on a plant and the number of flowers on a panicle on two callus lines in the second or third group were increased. No variability was detected in five callus lines, i.e., such a phenomenon was not a rule. The nuclear DNA content of doubled haploids in four groups of the same callus line was 1.03– 1.09 pg, and for haploids it was 0.53–0.58 pg. Intracallus variability of nuclear DNA content was detected between groups of haploids of the same line and among doubled haploids of the same line. Significant differences were found between the haploids of one callus line and the three other callus lines of the Sadko × Kuboyar hybrid towards an increase of nuclear DNA content (p < 0.0015). The theoretical possibility of the appearance of intraspecific variability among plants with a small number of chromosomes is considered. A scheme of genomic reorganization is proposed for such species: initial plant (2n) → aneuhaploid plants (n + 1) → megasporogenesis and microsporogenesis of the 0-n type, formation of fertile pollen (n + 1) → diploid plant (2n + 2). Aneuhaploid evolution explains the intraspecific variability of chromosome numbers among plant species with low ploidy. Aneuploid technologies can help in the artificial formation of new polyploid crops, and rice is given a primary role.
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