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Transformation of tobacco plants with virEl gene derived from Agrobacterium tumefaciens pTiA6 and its effect on crown gall tumor formation
53-56.Views:137The VirEl protein plays a key role in the transport of VirE2 protein from the bacterium to the plant cell during crown gall tumor induction by Agrobacterium. The virEl gene of A. tutnefaciens pTiA6 was cloned into the plant transformation vector pTd33 yielding pTd93virEl that was introduced into A. tuniefaciens EHA101 and used for tobacco transformation. The presence of the foreign DNA in the putative transgenic plants was confirmed by PCR analysis. Nine of the 41 transformed plants formed only small tumors following infection with the wild-type A. vitis octopine strain AB3. This property was inherited into the T1 generation. The expression of virEl gene in TI plants was demonstrated by Northern blot analysis.
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Comparison of Xanthomonas arboricola pv. juglandis isolates from walnut trees grown in Romania and Hungary
65-69.Views:262Among diseases that affect walnut, bacterial blight is considered the most important one in all walnut growing areas both from Hungary and Romania. For the determination of susceptibility/resistance of walnut cultivars in our posterior work planned, 61 bacterial isolates were collected from walnuts showing symptoms of blight, with the purpose of isolating Xanthomonas arboricola pv. juglandis (Xaj). The characteristic Xaj colonies, frequently present as saprophytes in the infected plant tissues, were separated from other bacteria according to their morphology, yellow colour, hydrolysis of starch, and oxidation of glucose. All isolates were tested for pathogenicity by hypersensitive reaction on tobacco leaves (Nicotiana tabacum L.), bean pods (Phaseolus vulgaris L) and unripe nuts (Juglans regia L.). Determination of taxonomy of the selected isolates denotes a possible subdivision (races, biotypes) of Xaj occurring in different geographical areas, API 20NE and API 50CH kits were used. Hungarian and Romanian strains showed a high degree of similarity of carbohydrate utilization but slightly differed from the type strain. All were Cu-sensitive.
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Preliminary biochemical studies on a model growing of different tobacco plant (Nicotiana tabacum L.) cultivars
83-87.Views:139The aim of our preliminary studies was to characterize the change in the activity of enzymes PPO and PDX, the concentration of total soluble phenolic compounds and soluble protein content of different tobacco cultivars measured in tobacco plants during cultivation. The results suggest that a shorter cultivation period (13-14 weeks) is more favourable for tobacco plants as protein source than for tobacco industrial use (16-17 weeks). We found some correlation between the concentration of total soluble phenolic compounds and PPO activity data. In the increasing and maximum period of total phenol content the PPO activity was high. But later because of decrease of substrate phenol content the activity of PPO also decreased. We found higher soluble protein concentrations in Virginia than in Burley varieties.
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General defense system in the plant kingdom II.
69-71.Views:128In addition to successes achieved in certain varieties in resistance breeding based on a defense reaction of host plants involving hypersensitive tissue destruction, resistant varieties putting a very strong selection pressure on pathogens have selected more and more aggressive types of pathogens. The never-ending race between plant and pathogen resulting from this can only be controlled by a defense system characterised by a different strategy. In each of the plant species that we bred a defence system was found, which contrary to hypersensitive reaction strives to keep the tissues at all costs and is not pathogen specific. This is implied in the term general defense system.