Anna Dimitrova - Academia.edu (original) (raw)

Papers by Anna Dimitrova

ARPHA Conference Abstracts

Wheat (Triticum aestivum L.) is a globally important crop for food and nutritional security that ... more Wheat (Triticum aestivum L.) is a globally important crop for food and nutritional security that requires sufficient water supply for optimal production. All stages of wheat growth and development are adversely affected by reduced water supply, which limit productivity across large areas of Central and Southern Europe. Since drought episodes are expected to occur more frequently and with a greater intensity, the research efforts are devoted to identification of key traits associated with drought resistance that could be used as direct and indirect selection criteria for wheat drought tolerance. We evaluated and quantified several key genetic and molecular features of wheat genotypes with contrasting drought tolerance under severe dehydration triggered by the treatment of wheat with 250 mM sorbitol in hydroponic systems. Plant status was evaluated non-destructively by measuring leaf chlorophyll index, nitrogen content, and leaf relative water content. The drought-tolerant genotype di...

Biotechnology & Biotechnological Equipment, 2021

Poster title: Morpho-physiological variation and antioxidant response of Bulgarian wheat cultivar... more Poster title: Morpho-physiological variation and antioxidant response of Bulgarian wheat cultivars after drought stress and subsequent recovery.

Dokladi Na B Lgarskata Akademiâ Na Naukite, 2008

Bulgarian Journal of Agricultural Science, 2019

Vassileva, V., Vaseva, I. & Dimitrova, A. (2019). Expression profi ling of DNA methyltransferase ... more Vassileva, V., Vaseva, I. & Dimitrova, A. (2019). Expression profi ling of DNA methyltransferase genes in wheat genotypes with contrasting drought tolerance. Bulgarian Journal of Agricultural Science, 25(5), 845–851 DNA methylation is a reversible epigenetic mechanism that affects important developmental processes and stress-related events in living organisms. The process of cytosine methylation is catalysed by DNA methyltransferases that are structurally and functionally conserved in all eukaryotes. This study assessed the effect of drought stress and subsequent rewatering on the transcription of DNA methyltransferase coding genes (TaMET1, TaMET2a, TaMET2b and TaMET3) in wheat genotypes with contrasting drought tolerance. The applied drought stress led to changes in leaf water defi cit in a variety-specifi c manner. Two of the wheat genotypes, Farmer and Bojana, performed as sensitive to drought, the other two, Yoana and Guinness, were considered as drought tolerant. Under drought ...

Zeitschrift für Naturforschung C, 2019

Hordeum vulgare and Hordeum bulbosum are two closely related barley species, which share a common... more Hordeum vulgare and Hordeum bulbosum are two closely related barley species, which share a common H genome. H. vulgare has two nucleolar organizer regions (NORs), while the NOR of H. bulbosum is only one. We sequenced the 2.5 kb 25S-18S region in the rDNA of H. bulbosum and compared it to the same region in H. vulgare as well as to the other Triticeae. The region includes an intergenic spacer (IGS) with a number of subrepeats, a promoter, and an external transcribed spacer (5′ETS). The IGS of H. bulbosum downstream of 25S rRNA contains two 143-bp repeats and six 128-bp repeats. In contrast, the IGS in H. vulgare contains an array of seven 79-bp repeats and a varying number of 135-bp repeats. The 135-bp repeats in H. vulgare and the 128-bp repeats in H. bulbosum show similarity. Compared to H. vulgare, the 5′ETS of H. bulbosum is shorter. Additionally, the 5′ETS regions in H. bulbosum and H. vulgare diverged faster than in other Triticeae genera. Alignment of the Triticeae promoter s...

Zeitschrift für Naturforschung C, 2011

In contrast to differentiated leaves, the regulatory mechanisms of chloroplast gene expression in... more In contrast to differentiated leaves, the regulatory mechanisms of chloroplast gene expression in darkened cotyledons have not been elucidated. Although some results have been reported indicating accelerated senescence in Arabidopsis upon reillumination, the capacity of cotyledons to recover after dark stress remains unclear. We analysed the effect of twodays dark stress, applied locally or at the whole-plant level, on plastid gene expression in zucchini cotyledons. Our results showed that in the dark the overall chloroplast transcription rate was much more inhibited than the nuclear run-on transcription. While the activities of the plastid-encoded RNA polymerase (PEP) and nuclear RNA polymerase II were strongly reduced, the activities of the nuclear-encoded plastid RNA polymerase (NEP) and nuclear RNA polymerase I were less affected. During recovery upon reillumination, chloroplast transcription in the cotyledons was strongly stimulated (3-fold) compared with the naturally senescing controls, suggesting delayed senescence. Northern blot and dot blot analyses of the expression of key chloroplast-encoded photosynthetic genes showed that in contrast to psbA, which remained almost unaffected, both the transcription rate and mRNA content of psaB and rbcL were substantially decreased.

Biotechnology & Biotechnological Equipment, 2000

Sphaerococcum mutant forms obtained after EMS treatment in T.aestivum (AABBDD) and 6x-Triticale (... more Sphaerococcum mutant forms obtained after EMS treatment in T.aestivum (AABBDD) and 6x-Triticale (AABBRR/2D) were studied at genetical, cytogenetical and molecular level. The initial genetic grouping was based on the existence of two types of sphaerococcum mutation; stable and unstable. Transposable elements like AciDs from wheat and Triticale are described in both Sphaerococcum mutant forms. Cytogeneticaly detectable chromosomal rearrangements including the main briges were established only in unstable mutant forms. Southern hybridization analysis of the unstable mutant forms, 49L sph and 49L aest indicated the presence of AciDs-/ike transposable elements in their genomes. The stable mutant form MT47 sph possesses Ds-like transposable element. Ac was present in the genome of mutant forms of 613, 6512, 491202/S1, S.r2x 613 and the control form ofT. aestivum (S.ranozreika 2). These observations provide a basis for the isolation and molecular characterization of the sphaerococcum locus in wheat and Triticale.

Summary. The methylation pattern of rRNA genes in reconstructed barley karyotypes ( Hordeum vulga... more Summary. The methylation pattern of rRNA genes in reconstructed barley karyotypes ( Hordeum vulgare L.) with altered position or structure of the two nucleolus organizers (NORs) was studied by double digestion with EcoRI and HhaI and molecular hybridization with specifi c rDNA probes. The lack of the whole rRNA gene cluster residing in chromosome 6H in the homozygous deletion line T-35 led to an increased hypomethylation of the rRNA genes in the remaining NOR5H. On the other hand, repositioning by translocation of the distant part of the split NOR6H to the short arm of the chromosome 5H in the translocation line T-21 did not correlate with any signifi cant changes in the methylation of –GCGC– sequences in rDNA units. In addition, the length of the intergenic spacer (IGS) in both reconstructed barley lines T35 and T21 was also analyzed. Our results showed the same length of IGS in the long rDNA repeat as compared with previously published rDNA clone (GenBank HQ825319). However, the s...

Mutagenesis, 1996

The clastogenic ability of the restriction endonucleases (Mspl, HpaU and HaeUl) in germinating se... more The clastogenic ability of the restriction endonucleases (Mspl, HpaU and HaeUl) in germinating seeds of reconstructed barley karyotype was assessed. An effective induction of chromosomal aberrations after restrictase treatment was observed. The frequency, types and cell-cycle dependence of the observed abnormalities are discussed in relation to the distinct characteristics of the enzymes and the features of the plant genome. The capacity to induce aberrations was not significantly influenced by the nature of the double-strand breaks (blunt-or cohesive-ended); however, it was dependent on the methylation status of the plant DNA. The restriction enzymes displayed an Sindependent mode of action revealing the transition between G] and S as the most sensitive stage of the cell cycle in barley for induction of chromosomal damage.