The severe strain of potato spindle tuber viroid (s‐PSTV) as well as chrysanthemum stunt (CSV) and cucumber pale fruit (CPFV) viroids were found to be transmitted through seed and pollen of the tomato cvs. Rutgers and Najwcześniejszy. Plants pollinated with a pollen infected with any of these three viroids became systematically infected. Plant, fruit and seed symptoms of viroid infection were noted on sap‐ and pollen‐inoculated plants and the yield of these plants was reduced.
Tomato cv. Rutgers plants grown from infected seeds were symptomless although all three viroids were detected in these plants by bioassay and by electrophoresis on 5% polyacrylamide gel.
When DNA complementary to s‐PSTV RNA was used for a direct viroid detection in seed samples by spot hybridization technique it hybridized not only with s‐PSTV RNA but also with CSV RNA as well as with CPFV RNA.
Isolation of RNA from plants rich in secondary metabolites using commercial kits often results in contaminated preparations which are not suitable for downstream applications. Although many specific protocols appropriate for plants with a high content of phenolics, anthocyanins and polysaccharides have been developed, these are often expensive, time consuming and not applicable to different types of tissues. This study presents a simple and efficient modification of RNA extraction from different types of tissues using two commercial reagent kits. By simple improvement, we routinely obtained high-quality RNA of the following plants: the blackcurrant bush, black chokeberry bush, pear tree, apricot tree, apple tree, hardy kiwi, tangerine tree, highbush blueberry and cranberry plant.
Viroid-free potato and chrysanthemum plants were obtained from meristem-tips cut from potato spindle tuber viroid-infected potato plants and from chrysanthemum plants infected with chrysanthemum stunt, chrysanthemum chlorotic mottle or cucumber pale fruit viroids after 6 months therapy in a growth chamber at 5 °C and 16 hours daily light of 5.000 lx intensity. Chrysanthemum plants survived quite well the conditions of therapy while potato plants grown from stem cuttings survived these conditions much worse and potato plants grown from tubers did not survive these conditions. PSTV-free plants were obtained from meristem-tips cut from sprouts grown from potato tubers infected with severe (s-PSTV) or mild (m-PSTV) strains of potato spindle tuber viroid after 6 months therapy at 6-7 °C in the dark. The tubers survived these conditions quite well.The 3 months therapy period was found too short for any plant material. The efficiency of 6 months therapy in viroid elimination varied for different viroids and different plant material from 18.5 to 80.0 %.
Prune dwarf virus (PDV) isolates have been investigated for genetic diversity. Full-length nucleotide and amino acid sequences of viral coat protein from 23 isolates collected from different stone fruit trees (sour and sweet cherry trees, wild cherry tree, plum tree, almond tree, peach tree) and different countries (Poland, Italy, Germany, USA, Israel) were analysed and compared to 57 others available in GenBank. Comparison of all sequenced virus isolates revealed diversity of 86-100 % at nucleotide level and 79-100 % at amino acid level. The ratio of non-synonymous to synonymous polymorphic sites indicated that purifying selection dominated in case of PDV. However, six codons showed to be under strong positive selection, including the codon located inside the structure involved in RNAbinding activity.
Garlic plants can be infected by different viruses including eight which belong to the genus Allexivirus, family Alphaflexiviridae. The aim of the research conducted was to detect and identify the allexiviruses GarV-A,
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