sequence of the coat protein (CP) gene and the 3' non-translated region, in
relation to aphid transmission of 7 potato tuber necrotic ringspot isolates of
Potato virus Y (PVYNTN) were studied. Five isolates originated from different
areas of potato fields in Hungary and two German isolates served as controls. A
5' tail of the nucleotide sequences of the CP region and 3' non-translated
region (NTR) were determined. Sequence data were sent to the EMBL GeneBank
Database. Homology of nucleotide and amino acid sequences were high among the
studied PVY isolates. According to the characteristic regions, all isolates
belonged to the PVYNTN strain. All of the tested isolates could be transmitted
by the aphid Myzus persicae Sulzer to the test plant Nicotiana tabacum L.
verifying the wide distribution of tuber necrotic ringspot strain in Hungary.
Our data suggest that the high homology found in the CP region of the different
isolates, are suitable for development of coat protein mediated resistance against
PVY in commercially important host plants like, e.g. potato.
The freshwater cyanoprokaryote Cylindrospermopsis raciborskii has become increasingly prevalent in tropical and temperate water bodies worldwide. The morphological characteristics of this species were investigated under different growth rates in continuous cultures (at steady state) and in batch (phosphorus starved) cultures with different mineral nitrogen forms. The species displays an enormous morphological variability under controlled condition. The occurrence of extreme long twisted filaments was found near the maximum growth rate and under high ammonium concentration. Rarely the heterocytes of Cylindrospermopsis raciborskii arise intercalarly between two neighboring cells (i.e. intercalary heterocytes were found). The morphological features are highly effected by environmental conditions and nutrient availability. Under P-starvation extreme morphology appeared. The specifications of C. africana and C. cuspis overlap with that of C. raciborskii accordingly this is not clear characteristic feature to distinguish species. A pure culture of a pro- or eukaryote alga growing in continuous cultures is a good method for giving a suitable overview on all morphological possibilities of a tested organism.