parthenogenesis

The article is a brief overview of the scientifi c heritage of professor V. S. Tyrnov (1941–2015). He was a one of the leading scientists in the fi eld of biology and genetics of plant reproduction. His research has made a signifi cant contribution to the understanding of reasons for and mechanisms of haploidy. V. S. Tyrnov was an author of original haploid production technologies in vivo and in vitro. He created a unique corn lines with heritable and non-heritable (induced) forms of parthenogenesis.

Megaspore- and megagametophytogenesis in tobacco mutant with reduced cells number in embryo sacs were studied. It is established, that the mutation causes a disturbance of one pair of homologous chromosomes conjugation in meiosis. Consequently alongside with the haploid (24-chromosomal) spores aneuploid (23-chromosomal) spores forms which are developed into abnormal embryo sacs. At cenocyte stage of megagametophytes development falling out of 1-2 mitoses and/or their abnormal course were observed, as well as abnormalities in embryo sacs polarization.

Many modern selection technologies are based on the use of haploid plants as a starting material. The spontaneous frequency of haploid development is very low (0.01–0.1%). In this regard, the creation of plant forms with increased frequency of parthenogenesis is important. The collection of corn lines with an increased frequency of haploid plants in the progeny was created at the Department of Genetics of the Saratov State University. High costs are required for maintain of a plant collections in the field.