The complete nucleotide sequence of a Polish isolate of Beet soil-borne virus was determined for the first time. The genome organization was identical with those previously established for isolates from Germany and China. A comparison of the Polish isolate with others deposited in GenBank reveled high level of nucleotide identity, about 98-100%, throughout the genome analyzed. The ratio between non-synonymous and synonymous substitutions was rather low suggesting a negative selective pressure. The non-synonymous mutations were particulary frequent in triple gene block.
Several different isolates of Tomato black ring virus (TBRV) have been collected in Poland from cucumber, tomato, potato and black locust plants. Biological tests showed some differences in the range of infected plants and the type of symptoms, which was the basis for selection of seven the most biologically different TBRV isolates. According to the sequence of TBRV-MJ, several primer pairs were designed and almost the entire sequence of both genomic RNAs was amplified. The RT-PCR products derived from all tested TBRV isolates were digested by restriction enzymes. On the basis of the restriction patterns, the variable and the conserved regions of the TBRV genome were defined and the relationships between the Polish TBRV isolates established.
Rizomania jest chorobą buraka cukrowego wywoływaną przez wirus nekrotycznego żółknięcia nerwów buraka BNYVV, który powoduje znaczące jakościowe i ilościowe straty plonu tej ekonomicznie istotnej rośliny w skali światowej. Za najbardziej skuteczną metodę walki z rozprzestrzenianiem choroby, umożliwiającą uprawę w warunkach porażenia uznaje się stosowanie odmian wyprowadzonych w toku hodowli odpornościowej. Jednakże żaden z dotychczas opisanych genów nie warunkuje całkowitej odporności, a jedynie tolerancję na wirus. Jednocześnie z powodu pojawiania się szczepów zdolnych do przełamywania odporności, przeszukiwanie zasobów dzikich form z rodzaju Beta jest kluczowe dla dalszej identyfikacji nowych źródeł odporności, a w konsekwencji dla utrzymania ciągłej produkcji konkurencyjnych odmian buraka cukrowego. W niniejszej pracy dokonano przeglądu znanych obecnie źródeł odporności, jak również przedstawiono podstawowe mechanizmy istotne dla jej wykształcenia.
EN
Rhizomania is a disease of sugar beet induced by Beet necrotic yellow vein virus (BNYVV) that has been responsible for both quantitative and qualitative significant yield losses of this economically important crop worldwide. The most effective method of protection that enables production under infestation conditions is believed to be resistance breeding. However, none of the genes identified thus far seems to be able to condition a fully resistant genotype. Additionally, due to the appearance of resistance-breaking strains of the virus, screening of wild relatives is crucial for further identification of new resistance sources and, consequently, for continuous production of competitive sugar beet cultivars. This review presents an overview of currently known resistance sources as well as highlights some basic mechanisms involved in resistance expression.
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