On the Possibility of Experimental Modification of Imprinting in Apomictic Plants

Resumo

The paper shows the possibility of experimental modification of the expression of imprinting in apomictic hybrids of maize with gamagrass through exposure to a synthetic nucleoside 5-azacytidine, which inhibits DNA methylation. In angiosperm plants with double fertilization, the ratio of maternal and paternal genomes in endosperm cells is usually 2F : 1M, respectively. Moreover, any deviations from it, most often lead to abortion of grains. Apomictic pseudogamous plants, in which seed fertilization requires the fertilization of the central cell, have developed various mechanisms to overcome the negative effect of imprinting associated with a deviation in the ratio of parental genomes in the endosperm from 2 : 1. However, in such an apomict as tetraploid gamagrass (Tripsacum dactyloides), owing to a significant deviation in the ratio of genomes in the endosperm, only about 25% of the seeds are viable and produce seedlings. The same picture is characteristic of its apomictic hybrids with corn. In this regard, we tried using 5-azacitidine to modify female imprinting and enhance the expression of genes, the dose of which is insufficient owing to the discrepancy between the number of paternal genomes and the required ratio. The results obtained suggest the possibility of modifying the expression of imprinting. At the same time, the effect of 5-azacytidine is found in both M₁ and the next three generations. In M₂, families are distinguished in which, compared to the control, not only the difference in averages but also the frequency nature of the experimental and control distributions on the basis of “grain weights” is reliable.