Vesela Radeva - Academia.edu (original) (raw)

Papers by Vesela Radeva

Journal of Phytopathology, 2012

PLoS ONE, 2020

Region-specific local landraces represent a germplasm diversity adapted and acclimatized to local... more Region-specific local landraces represent a germplasm diversity adapted and acclimatized to local conditions, and are ideal to breed for targeted market niches while maintaining the variability of heirloom traits. A collection of 180 pepper accessions, collected from 62 diverse locations across six Balkan countries, were characterized and evaluated for phenotypic and biochemical variation during a multi-year environment. An assortment of 32 agro-morphological , fruit quality, and virus resistance traits were evaluated, and the top 10% accessions were identified. A wide range of trait variation concerning plant architecture, inflorescence and fruit traits, yield and fruit quality was observed, and appreciable variation was noticed. According to hierarchical clustering, six distinct clusters were established based on pre-defined varietal groups. Divergence among accessions for phenotypic and fruit compositional variability was analyzed, and eight principal components were identified that contributed~71% of the variation , with fruit shape, width, wall thickness, weight, and fruit quality traits being the most dis-criminant. Evaluation of the response to tobacco mosaic virus (TMV) and pepper mild mottle mosaic virus (PMMoV) showed that 24 and 1 accession were resistant, respectively while no tomato spotted wilt virus (TSWV) resistance was found. Considerable diversity for agro-bio-morphological traits indicates the Balkan pepper collection as good gene sources for pre-breeding and cultivar development that are locally adapted.

Biotechnology & Biotechnological Equipment, 2010

In this paper we investigate the changes in fresh weight, chlorophyll content, catalase and guiac... more In this paper we investigate the changes in fresh weight, chlorophyll content, catalase and guiacol peroxidase activities of nine oxidative stress-tolerant atr (AAL-toxin resistant) Arabidopsis thaliana mutants subjected to cadmium stress. We show that atr2, atr7 and atr9 are more tolerant to CdCl 2 . There was no significant change in catalase activity under cadmium treatment in all atr lines including the parental line loh2 compared with untreated seedlings. All lines but atr9 showed reduction in guaiacol peroxidase activity. This suggests that the sensitivity to the cadmium-induced oxidative stress at least in some lines is linked to impaired reactive oxygen species.

Acta Physiologiae Plantarum, 2011

We have previously reported a method for isolation of mutants with enhanced tolerance to the fung... more We have previously reported a method for isolation of mutants with enhanced tolerance to the fungal AAL toxin and given a detailed characterization of atr1 (AAL toxin resistant, Gechev et al. in Biochem Biophys Res Commun 375:639–644, 2008). Herewith, we report eight more mutants with enhanced tolerance to the AAL toxin. Phenotypic analysis showed that six of the mutants were reduced in size compared with their original background loh2. Furthermore, atr2 showed delayed flowering and senescence. The mutants were also evaluated for oxidative stress tolerance by growing them on ROS-inducing media supplemented with either aminotriazole or paraquat, generating, respectively, H2O2 or superoxide radicals. Oxidative stress, confirmed by induction of the marker genes, HIGH AFFINITY NITRATE TRANSPORTER At1G08090 and HEAT SHOCK PROTEIN 17 At3G46230, inhibited growth of all lines. However, while the original background loh2 developed necrotic lesions and died rapidly on ROS-inducing plant growth media, atr1, atr2, atr7 and atr9 remained green and viable. The tolerance against oxidative stress-induced cell death was confirmed by fresh weight and chlorophyll measurements. Real-time PCR analysis revealed that the expression of the EXTENSIN gene At5G46890, previously shown to be downregulated by aminotriazole in atr1, was repressed in all lines, consistent with the growth inhibition induced by oxidative stress. Taken together, the data indicate a complex link between growth, development and oxidative stress tolerance and indicates that growth inhibition can be uncoupled from oxidative stress-induced cell death.

Programmed cell death (PCD) is essential for plant development and stress responses. In order to ... more Programmed cell death (PCD) is essential for plant development and stress responses. In order to gain insights into PCD in plants, Molecular biology and Genetics approaches were applied to discover genes involved in the regulation and execution of the cell death in Arabidopsis thaliana. Using the fungal AAL-toxin and hydrogen peroxide (H 2 O 2 ) as cell death triggers, a comprehensive transcriptional analysis revealed a set of genes regulated in a common fashion by the two PCD stimuli. These included an oxoglutarate-dependent dioxygenase and various oxidoreductases, the transcription factors Zat11, WRKY75 and NAM, proteasomal components, a heterologous group of genes with diverse functions, and genes encoding proteins with unknown functions. A number of those genes are being functionally studied by gene silencing or isolating homozygous knockout lines. In addition, our group has isolated mutants that are more tolerant to AT as well as to the fungal AAL toxin, thus indicating a new link between redox and sphingolipid signaling. These genetic studies were further substantiated by molecular and biochemical data bringing new insights into the interplay between H 2 O 2 and sphingolipids during PCD.

Journal of Phytopathology, 2012

PLoS ONE, 2020

Region-specific local landraces represent a germplasm diversity adapted and acclimatized to local... more Region-specific local landraces represent a germplasm diversity adapted and acclimatized to local conditions, and are ideal to breed for targeted market niches while maintaining the variability of heirloom traits. A collection of 180 pepper accessions, collected from 62 diverse locations across six Balkan countries, were characterized and evaluated for phenotypic and biochemical variation during a multi-year environment. An assortment of 32 agro-morphological , fruit quality, and virus resistance traits were evaluated, and the top 10% accessions were identified. A wide range of trait variation concerning plant architecture, inflorescence and fruit traits, yield and fruit quality was observed, and appreciable variation was noticed. According to hierarchical clustering, six distinct clusters were established based on pre-defined varietal groups. Divergence among accessions for phenotypic and fruit compositional variability was analyzed, and eight principal components were identified that contributed~71% of the variation , with fruit shape, width, wall thickness, weight, and fruit quality traits being the most dis-criminant. Evaluation of the response to tobacco mosaic virus (TMV) and pepper mild mottle mosaic virus (PMMoV) showed that 24 and 1 accession were resistant, respectively while no tomato spotted wilt virus (TSWV) resistance was found. Considerable diversity for agro-bio-morphological traits indicates the Balkan pepper collection as good gene sources for pre-breeding and cultivar development that are locally adapted.

Biotechnology & Biotechnological Equipment, 2010

In this paper we investigate the changes in fresh weight, chlorophyll content, catalase and guiac... more In this paper we investigate the changes in fresh weight, chlorophyll content, catalase and guiacol peroxidase activities of nine oxidative stress-tolerant atr (AAL-toxin resistant) Arabidopsis thaliana mutants subjected to cadmium stress. We show that atr2, atr7 and atr9 are more tolerant to CdCl 2 . There was no significant change in catalase activity under cadmium treatment in all atr lines including the parental line loh2 compared with untreated seedlings. All lines but atr9 showed reduction in guaiacol peroxidase activity. This suggests that the sensitivity to the cadmium-induced oxidative stress at least in some lines is linked to impaired reactive oxygen species.

Acta Physiologiae Plantarum, 2011

We have previously reported a method for isolation of mutants with enhanced tolerance to the fung... more We have previously reported a method for isolation of mutants with enhanced tolerance to the fungal AAL toxin and given a detailed characterization of atr1 (AAL toxin resistant, Gechev et al. in Biochem Biophys Res Commun 375:639–644, 2008). Herewith, we report eight more mutants with enhanced tolerance to the AAL toxin. Phenotypic analysis showed that six of the mutants were reduced in size compared with their original background loh2. Furthermore, atr2 showed delayed flowering and senescence. The mutants were also evaluated for oxidative stress tolerance by growing them on ROS-inducing media supplemented with either aminotriazole or paraquat, generating, respectively, H2O2 or superoxide radicals. Oxidative stress, confirmed by induction of the marker genes, HIGH AFFINITY NITRATE TRANSPORTER At1G08090 and HEAT SHOCK PROTEIN 17 At3G46230, inhibited growth of all lines. However, while the original background loh2 developed necrotic lesions and died rapidly on ROS-inducing plant growth media, atr1, atr2, atr7 and atr9 remained green and viable. The tolerance against oxidative stress-induced cell death was confirmed by fresh weight and chlorophyll measurements. Real-time PCR analysis revealed that the expression of the EXTENSIN gene At5G46890, previously shown to be downregulated by aminotriazole in atr1, was repressed in all lines, consistent with the growth inhibition induced by oxidative stress. Taken together, the data indicate a complex link between growth, development and oxidative stress tolerance and indicates that growth inhibition can be uncoupled from oxidative stress-induced cell death.

Programmed cell death (PCD) is essential for plant development and stress responses. In order to ... more Programmed cell death (PCD) is essential for plant development and stress responses. In order to gain insights into PCD in plants, Molecular biology and Genetics approaches were applied to discover genes involved in the regulation and execution of the cell death in Arabidopsis thaliana. Using the fungal AAL-toxin and hydrogen peroxide (H 2 O 2 ) as cell death triggers, a comprehensive transcriptional analysis revealed a set of genes regulated in a common fashion by the two PCD stimuli. These included an oxoglutarate-dependent dioxygenase and various oxidoreductases, the transcription factors Zat11, WRKY75 and NAM, proteasomal components, a heterologous group of genes with diverse functions, and genes encoding proteins with unknown functions. A number of those genes are being functionally studied by gene silencing or isolating homozygous knockout lines. In addition, our group has isolated mutants that are more tolerant to AT as well as to the fungal AAL toxin, thus indicating a new link between redox and sphingolipid signaling. These genetic studies were further substantiated by molecular and biochemical data bringing new insights into the interplay between H 2 O 2 and sphingolipids during PCD.