StatusThe thesis was presented on the 8 August, 2018
Approved by NCAA on the 23 November, 2018
Abstract– 1.43 Mb / in romanian
3.93 Mb /
The thesis includes introduction, four chapters, general conclusions and recommendations, bibliography of 299 sources, total volume of 132 pages, 11 tables, 42 figures. The obtained results are published in 12 scientific papers.
Field of study: Plant genetics. The purpose of the research: the goal of this work consists in estimation of the role of gibberellin (GA3) in initiation and regulation of cell division in anthers of sunflower.
Objectives of the thesis: to estimate the correlation of the tubular flowers size and anthers with microsporogenesis phases and microgametogenesis; to determine the histoanatomical peculiarities of development of microsporangium in the plants of fertile sunflower with cytoplasmic and induced androsterility; to recognize the morpho-physiological indices of meiocytes and microspores in treated and untreated plants with gibberellin; to elucidate the cytogenetic peculiarities of the meiotic division in sunflower; to study the expression of some genes involved in sunflower microsporogenesis under the influence of gibberellin.
Scientific novelty and originality. For the first time the transcriptional activity of the genes PCNA1, Cyclin D3, HIS1-3, H3.1, AHP2, MND1, DYAD, ASK1, EXPA1 and GSL12 involved in the reproduction process of sunflower, which allowed the correlation of the pattern of expression with the presence of chromosome aberrations, degradation of the tapetal layer, meiocytes with degenerated shape and structure, sterile pollen in plants with IMS and their lack of in those with CMS have been evaluated. Histoanatomical and cytogenetic studies have highlighted new aspects of differentiated development of microsporangium tissues during microsporogenesis in induced male sterility plants and those with cytoplasmic androsterility compared to fertile sunflower plants. The gametocidal effect of gibberellin was demonstrated by diminishing anthers, was identified a large number of chromosomal aberrations in treated plants and total inhibition of meiosis in CMS.
The most important solved scientific problem consists in explanation of the gibberellins role in initiating and regulating the cell division in the anther of sunflower, in a model system (fertile plants, with cytoplasmic male sterility and induced androsterility) that contributes to explanation the patterns of differentiated expression of genes involved in microsporogenesis depending on the type of sterility, identification of the phase in which meiosis was disrupted in plants with IMS through the formation of sterile grains of pollen and lack thereof in plants with CMS, which allowed clarification of the mechanisms of induction of androsterility.
The theoretical significance. The results presented extend the existing knowledge of the histoanatomical and cytological mechanisms of the transition from diploid sporophyte to the haploid gametophyte of sunflower plants with induced and cytoplasmic male sterility. Research is aimed at substantiating the information about the action of gibberellin on the fertility in sunflower and microsporangium in fertile plants and cytoplasmic androsterility and development of a hypothetical scheme, which would describe the basic elements of male sterility induction at different stages of the pollen mother cells development.
The applied value of the work. The methods of photonic microscopy and ultramicrotomation have been implemented in the Laboratory of Genomics that contribute efficient investigation of the processes or mechanisms related to molecular studies, have been appropriated. The bioinformatical and molecular, via Real-Time PCR method, study provided for the identification of genes involved in microsporogenesis with a priority and potential role in the androsterility of sunflower.
Implementation of scientific results. The data obtained and exhibited in the thesis serve as scientific material during teaching of courses on molecular biology and cellular biology. Specific primers developed from EST sequences of the NCBI database, with the purpose of investigation of the expression of 10 genes from sunflower plants with induced and cytoplasmic androsterility are applied in the Centre Functional Genetics of State University “Dimitrie Cantemir” and are recommended for implementation in further genetical-molecular investigations