In this paper we describe the first procedure for Agrobacterium tumefaciens-mediated genetic tran... more In this paper we describe the first procedure for Agrobacterium tumefaciens-mediated genetic transformation of the desiccation tolerant plant Ramonda myconi (L.) Rchb. Previously, we reported the establishment of a reliable and effective tissue culture system based on the integrated optimisation of antioxidant and growth regulator composition and the stabilisation of the pH of the culture media by means of a potassium phosphate buffer. This efficient plant regeneration via callus phase provided a basis for the optimisation of the genetic transformation in R. myconi. For gene delivery, both a standard (method A) and a modified protocol (method B) have been applied. Since the latter has previously resulted in successful transformation of another resurrection plant, Craterostigma plantagineum, an identical protocol was utilized in transformation of R. myconi, as this method may prove general for dicotyledonous resurrection plants. On this basis, physical and biochemical key variables in transformation were evaluated such as mechanical microwounding of plant explants and in vitro preinduction of vir genes. While the physical enhancement of bacterial penetration was proved to be essential for successful genetic transformation of R. myconi, an additional two-fold increase in the transformation frequency was obtained when the above physical and biochemical treatments were applied in combination. All R0 and R1 transgenic plants were fertile, and no morphological abnormalities were observed on the whole-plant level.
The fact that production is often unsuccessful even when resistant varieties are selected on the ... more The fact that production is often unsuccessful even when resistant varieties are selected on the basis of the hypersensitive reaction can be attributed to the lack of adequate knowledge on plant disease resistance. In addition to specific plant responses to pathogen species, plants also possess an aspecific defense reaction which, instead of causing rapid tissue destruction, is based on the opposite strategy, protecting the plant against attack by microbes through tissue compaction achieved by cell enlargement and cell division. Genetic analyses carried out in pepper revealed that the general defense reaction was inherited as a monogenic recessive trait (gds). Pathophysiological observations indicate that the stimulus threshold is lower and the reaction rate faster than for specific defense reactions. Biochemical analyses suggest that, unlike plants exhibiting rapid tissue destruction, plants containing the gds gene do not require an oxidative burst elicited by hydrogen peroxide to stimulate the defense m...
The purpose of this work was to further investigate the regulatory interplay between pyrophosphat... more The purpose of this work was to further investigate the regulatory interplay between pyrophosphate:fructose 6-phosphate 1-phosphotransferase (PFP) and its positive effector, fructose 2,6-bisphosphate (Fru-2,6-P2), in the storage organs of cold- and drought-stressed plants. Since there is no detectable cytoplasmic fructose-1,6-bisphosphatase (cytFBPase) activity in the taproots of carrot plants, PFP is the only enzyme that can replace its function when stored starch is converted to transportable sucrose. The working hypothesis was that PFP is likely to be involved in the mobilisation of energy reserves and might have a special role in storage organs such as carrot taproots upon stress. Both cold and drought stress resulted in a marked increase in the endogenous Fru-2,6-P2levels. It is suggested that the significant changes in photosynthate allocation are the direct results of the stimulation of PFP activity by elevated Fru-2,6-P2levels. PFP stimulated by Fru-2,6-P2operated in the gluconeogenic direction in the taproots of stressed carrot plants, whereas the glycolytic direction was dominant in the non-stressed controls. This suggests that the metabolic status determining the net activity of PFP depends on the physiological stress situation, making PFP an important sensor of environmental changes. The experimental data indicated that PFP is involved in the mobilisation of energy reserves during unfavourable environmental changes by promoting the re-synthesis of transportable sucrose in taproots.
The purpose of this study was to search for physiological parameters that provide an early indica... more The purpose of this study was to search for physiological parameters that provide an early indication of the morphogenetic response of leaf disc explants to different tissue culture-level manipulations in order to design an accelerated optimisation process for this technology. Tobacco (Nicotiana tabacum L. cv. Samsun) was chosen as model in our studies, because this is still one of the
Procedures previously established for plant regeneration and Agrobacterium tumefaciens-mediated g... more Procedures previously established for plant regeneration and Agrobacterium tumefaciens-mediated genetic transformation of the desiccation-tolerant plant, Craterostigma plantagineum, have been further developed. A highly effective tissue culture system was established based on the integrated optimisation of antioxidant and growth regulator composition and the stabilisation of the pH of the culture media by means of a potassium phosphate buffer. The undesirable hyperhydricity
In this paper we describe the first procedure for Agrobacterium tumefaciens-mediated genetic tran... more In this paper we describe the first procedure for Agrobacterium tumefaciens-mediated genetic transformation of the desiccation tolerant plant Ramonda myconi (L.) Rchb. Previously, we reported the establishment of a reliable and effective tissue culture system based on the integrated optimisation of antioxidant and growth regulator composition and the stabilisation of the pH of the culture media by means of a potassium phosphate buffer. This efficient plant regeneration via callus phase provided a basis for the optimisation of the genetic transformation in R. myconi. For gene delivery, both a standard (method A) and a modified protocol (method B) have been applied. Since the latter has previously resulted in successful transformation of another resurrection plant, Craterostigma plantagineum, an identical protocol was utilized in transformation of R. myconi, as this method may prove general for dicotyledonous resurrection plants. On this basis, physical and biochemical key variables in transformation were evaluated such as mechanical microwounding of plant explants and in vitro preinduction of vir genes. While the physical enhancement of bacterial penetration was proved to be essential for successful genetic transformation of R. myconi, an additional two-fold increase in the transformation frequency was obtained when the above physical and biochemical treatments were applied in combination. All R0 and R1 transgenic plants were fertile, and no morphological abnormalities were observed on the whole-plant level.
The fact that production is often unsuccessful even when resistant varieties are selected on the ... more The fact that production is often unsuccessful even when resistant varieties are selected on the basis of the hypersensitive reaction can be attributed to the lack of adequate knowledge on plant disease resistance. In addition to specific plant responses to pathogen species, plants also possess an aspecific defense reaction which, instead of causing rapid tissue destruction, is based on the opposite strategy, protecting the plant against attack by microbes through tissue compaction achieved by cell enlargement and cell division. Genetic analyses carried out in pepper revealed that the general defense reaction was inherited as a monogenic recessive trait (gds). Pathophysiological observations indicate that the stimulus threshold is lower and the reaction rate faster than for specific defense reactions. Biochemical analyses suggest that, unlike plants exhibiting rapid tissue destruction, plants containing the gds gene do not require an oxidative burst elicited by hydrogen peroxide to stimulate the defense m...
The purpose of this work was to further investigate the regulatory interplay between pyrophosphat... more The purpose of this work was to further investigate the regulatory interplay between pyrophosphate:fructose 6-phosphate 1-phosphotransferase (PFP) and its positive effector, fructose 2,6-bisphosphate (Fru-2,6-P2), in the storage organs of cold- and drought-stressed plants. Since there is no detectable cytoplasmic fructose-1,6-bisphosphatase (cytFBPase) activity in the taproots of carrot plants, PFP is the only enzyme that can replace its function when stored starch is converted to transportable sucrose. The working hypothesis was that PFP is likely to be involved in the mobilisation of energy reserves and might have a special role in storage organs such as carrot taproots upon stress. Both cold and drought stress resulted in a marked increase in the endogenous Fru-2,6-P2levels. It is suggested that the significant changes in photosynthate allocation are the direct results of the stimulation of PFP activity by elevated Fru-2,6-P2levels. PFP stimulated by Fru-2,6-P2operated in the gluconeogenic direction in the taproots of stressed carrot plants, whereas the glycolytic direction was dominant in the non-stressed controls. This suggests that the metabolic status determining the net activity of PFP depends on the physiological stress situation, making PFP an important sensor of environmental changes. The experimental data indicated that PFP is involved in the mobilisation of energy reserves during unfavourable environmental changes by promoting the re-synthesis of transportable sucrose in taproots.
The purpose of this study was to search for physiological parameters that provide an early indica... more The purpose of this study was to search for physiological parameters that provide an early indication of the morphogenetic response of leaf disc explants to different tissue culture-level manipulations in order to design an accelerated optimisation process for this technology. Tobacco (Nicotiana tabacum L. cv. Samsun) was chosen as model in our studies, because this is still one of the
Procedures previously established for plant regeneration and Agrobacterium tumefaciens-mediated g... more Procedures previously established for plant regeneration and Agrobacterium tumefaciens-mediated genetic transformation of the desiccation-tolerant plant, Craterostigma plantagineum, have been further developed. A highly effective tissue culture system was established based on the integrated optimisation of antioxidant and growth regulator composition and the stabilisation of the pH of the culture media by means of a potassium phosphate buffer. The undesirable hyperhydricity
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Under the United Nations Framework, Convention on Climate Change, Ministry of National Development, Department for Climate Policy