The methylation-sensitive amplified polymorphism (MSAP) technique using HpaII and MspI isoschizomers was used to analyse DNA-methylation alterations in stressed grapevine plants. The stress used was in vitro propagation via nodal segments and in vitro thermotherapy for virus elimination. A set of pertinent grapevine plants derived from two cultivars (18 plants each for Müller Thurgau and Riesling) was used as stressed variants for analyses. A total of 695 and 700 MSAP bands were recognised and evaluated as present/absent for all analysed variants derived from both cvs. Müller Thurgau and Riesling. Average computed similarity of MSAP banding between analysed variants (Dice/Nei and Li coefficient) was 0.935 for both cultivars. Clustering of variants within resulting dendrograms showed significant differences between woody cuttings despite originating from the one plant. Further, there was a strong 'donor' effect of maternal plants on future arrays of DNA methylation in their regenerants. The 'donor' effect even seemed to prevail in the effect of stress on final DNA-methylation state in stressed regenerants. Additional MSAP evaluation suggests that thermotherapy induced an additional array of methylation changes when compared with stress caused by in vitro cultivation. From the viewpoint of whether methylation of CCGG loci increased/decreased due to stress, the results showed moderate prevalence for decreasing CCGG loci methylation.

The Amplification Fragment Length Polymorphism (AFLP) technique was employed to study genetic variations which can be induced in vines by the stress occurring during different aspects of viticulture (in vitro cultivation, in vitro thermotherapy and virus infection). Analysis of AFLP banding patterns, generated by using 15 primer combinations, pointed to negligible genetic variation among plants exposed to individual stress. The average of similarity coefficients between differently stressed plants of the cultivars Müller Thurgau and Riesling were 0.984 and 0.991, respectively, as revealed by AFLP analysis. The low incidence of observed polymorphism demonstrates the high level of genome uniformity in plants reproduced by in vitro micropropagation via nodes, those subjected to in vitro thermotherapy and virus-infected plants.

ABSTRACT:The submitted work deals with the relation between the sum of active temperatures above 7°C and important phenological phases in peach tree cultivation. The aim of the paper is to provide information for growers, especially regarding anticipated harvest dates, which is important for marketing. Data has been compiled for the period 1998-2007 for the variety Catherine, grown in the locality of Velké Bílovice in the Czech Republic. A relationship between the sum of active temperatures above 7°C from the beginning of the year up to the start of blossoming has been identified, and a model determining the harvest date on the basis of the sum of active temperatures in the periods of 30 days and 60 days after blossoming has been tested. conditions. We can also assume that an increase in weather variability, as it is suggested in some studies concerning climate change, will lead to an increase in variation in the start of individual phenophases.The goals of this study were as follows: to test the possibility of using the sum of effective hourly temperatures for a model of the onset of peach tree phenophases and to predict the date of harvest for the selected cultivar. MATERIAL AND METHODSIn assessing the relationship between meteorological factors and the start of phenophases in peaches, we have used average hourly air temperatures. The compiled phenological observations refer to the variety Catherine (synonym Frederika-Catharina, Čepička et al. 1999) in Velké Bílovice, where air temperatures were precisely recorded at fifteenminute intervals with the aid of a HOBO recorder (see e.g. Litschmann 1999) placed close to the observed orchard. The study period comprised the years 1998-2007.We focused on the assessment of the start of blossoming and the start of harvest; these dates were carefully recorded every year. Blossoming was determined as stage F by Baggiolini (1952) (or 65 by BBCH, i.e. at least 50% of flowers open, first petals falling). The beginning of harvest was determined as the period when most fruits reached the optimum market maturity.From the meteorological data, we calculated the sum of active hourly temperatures above the base of 7°C (SAT7), starting from 1 st January every year. In the published literature this index is referred to as GDH (Growing Degree Hours); though, Peréz-Pastor et al. (2004) used it with a base of 6°C. DeJong (2005) used a combination of two cosine curves to calculate GDH, as follows: t ≤ 25: GDH = 10.5 (1 + cos (3.14 + 3.14 (t -4)/(25 -4))) t > 25: GDH = 21 (1 + cos (3.14/2 + 3.14/2 (t -25)/(36 -25))) where: t -temperature (°C).We tried to use this method in our own study, but we failed to reach more exact results. The retarding influence of higher temperatures on phenological development is probably not so critical under the conditions of South Moravia, where the relatively cooler climate prevails. RESULTS AND DISCUSSION Start dates of individual phenophases and temperature characteristics in individual yearsThe average blossoming start date (period 1994 to 2007) of the se...

The study overviews results of bacterial incidence in in vitro plant tissue cultures obtained from commercial laboratory dealing with plants micropropagation. For the exploration, the 454 pyrosequencing of the 16S rRNA gene was used. Three samples of plant in vitro cultures with visual bacterial contamination were subjected for identification of present bacteria. Eleven genera as Acinetobacter, Lactobacillus, Methylobacterium, Roseomonas, Microbacterium, Mycobacterium, Curtobacterium, Acidovorax, Magnetospirillum, Chryseobacterium and Ralstonia were detected. Obtained results confirmed the advantages of high‑throughput amplicon sequencing analysis for identification of bacterial communities in contaminated plant in vitro cultures what provides an important information for applying appropriate measures to eliminate bacterial contamination.

ABSTRACT:In this paper, results of the in vitro treatment are compared with those of in vivo therapy (i.e. treatment of plants in a peat substrate) when eliminating GFLV (Grapevine fanleaf virus) from three grapevine rootstocks. Therapy took 45 days under the temperature of 37°C in both cases. As far as the health condition of treated plants was concerned, no differences were found between the two methods. The differences were manifested in numbers of plants dying during the therapy and in the course of cultivation of apical segments treated with thermotherapy. Based on these results, it can be recommended to apply the thermotherapy in vivo, which -as compared with the in vitro method -enables us to obtain a greater number of apical segments from treated plants and to establish a smaller number of in vitro cultures in the course of the treatment. A shorter period of in vitro cultivation of plants is another advantage of this method because it helps to reduce the risk of somaclonal variability.