Comparative characteristics of karyometric parameters of microsporocytes and tapetum cells of the formed anthers of long-styled and short-styled plants Jasminum fruticans L. (Oleaceae)

In connection with the study of the functional activity of generative structures in heterostylous plants, a comparative karyometric analysis of tapetum cells, as well as microsporocytes of the formed anthers of long-styled and short-styled plants Jasminum fruticans L. (Oleaceae) was carried out. Based on the measurement of the nucleus areas, nucleolus, counting the number of nuclei and nucleoli in cells, the total values of the areas of nuclear structures were calculated. Since the processes of transcription and transformation of ribosomal RNA (r-RNA) are associated with nucleoli, the state of nucleolar structures in a cell reflects the level of its functional activity, therefore, the value of the nuclear-nucleolar ratio (NNR) was used as a characteristic of the functional activity of cells. It was found that in both floral forms, binuclear tapetal cells predominate. The number of nucleoli per cell varies from 1 to 14. The number of tapetal cells with 6-8 nucleoli is greater in short-styled plants than in long-styled plants. However, the cells of tapetum of long-styled and short-styled plants do not have a statistically significant difference of the value of NNR. Comparison of karyometric parameters of microsporocytes showed that the areas of their nuclear structures are larger in long-styled plants, while they are characterized by a higher value of NNR (17.61±0.36) compared with short-styled plants (15.59±0.27). A decrease in the value of NNR in short-styled plants is a sign of an increase in the intensity of protein metabolism of their microsporocytes, and, consequently, the level of functional activity of their genomes. Differences in the functional activity of microsporocytes of long-styled and short-styled plants can be considered as a sign of sex manifestation of sex depending on the floral type of the plant.