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Saffron latent virus (SaLV) is a species of the genus Potyvirus. The virus has only been reported from saffron (Crocus sativus L.), which is mainly cultivated in Iran, where some other species of Crocus are cultivated as ornamental plants/flowers. The sequence and organization of the SaLV genome has been determined, but there is a lack of information about its natural and herbaceous hosts as well as transmission by insect vectors that may affect the risks of disease emergence. The occurrence of natural infections of SaLV in Crocus almehensis, Crocus speciosus, and Crocus caspius was investigated by reverse transcription-polymerase chain reaction (RT-PCR) using specific primers, and only infections in C. almehensis were found. Moreover, mechanical inoculation of Chenopodium amaranticolor, Chenopodium quinoa, Chenopodium murale, Chenopodium album, Nicotiana rustica, Datura metel, and Capsicum annuum confirmed that these plant species are local /systemic indicator hosts of SaLV. Transmission of SaLV by Aphis gossypii, Aphis fabae, and Myzus persicae showed no statistically significant differences in efficiency. Pairwise sequence comparisons of sequenced isolates revealed an amino acid substitution of the second valine (V) by isoleucine (I) in the FVVRG motif of the P1-Pro protein. No correlation with geographic origin was found among the analyzed SaLV isolates when the phylogenetic trees were constructed based on P1-Pro and P3 genomic regions. Estimated dN/dS values showed that P1-Pro and P3 were under purifying selection pressure, but not as strong as the coat protein region. Estimation of population genetic parameters based on the P1-Pro and P3 regions, showed that different SaLV isolates were not geographically differentiated, confirming gene flow among different SaLV geographical subpopulations.

Rhizoctonia solani is an important pathogen of potatoes causing stem canker and black scurf. The fungus is a species complex comprised of 13 known anastomosis groups (AGs). AG3-PT is the anastomosis group frequently associated with disease in potatoes. A real-time PCR assay was designed to the rDNA ITS region of AG3-PT isolates to enable the pathogen to be detected directly in tuber and soil samples. The resulting assay was highly specific for AG3-PT, and did not amplify DNA from isolates from other AGs or subgroups of AG3. Using a bulk DNA extraction method capable of extracting from up to 250 g of soil, the assay could detect one individual sclerotium of AG3-PT (weighing 200 μg) in 250 g of soil. The AG3-PT assay was used, with assays for AG2-1, AG5 and AG8 to determine the prevalence of those AGs in UK potato soils and tubers. AG2-1 and AG3-PT were the predominant groups in tubers and soils, although AG3-PT was more frequently isolated from tubers, highlighting its importance as a potato pathogen. AG3-PT was also detected in more than half of the tuber samples tested suggesting the importance of seed borne inoculum.

We tested 212 bacterial isolates isolated from tomato and pepper plants suspected of being infected by Xanthomonas vesicatoria (causing bacterial spot). Samples from plants were collected in the years 2007–2010 from fields located in central Bohemia and central and south Moravia. For detection of the pathogens we used PCR with two previously published primer pairs (RST65, RST69 and XCVF, XCVR) and one primer pair (Xv1, Xv2) designed for specific detection of Xanthomonas vesicatoria. In total, 121 of 212 (57 %) samples were positive in PCR. In this article we provide data for additional verification of the newly designed (Xv1, Xv2) primers. Our results confirm the need of precise detection methods, because several tomato and pepper pathogens can share similar visual symptoms. We also suggest, that new PCR primers for detection of bacterial spot of tomato and pepper pathogens should not be overlooked, because they can improve currently used PCR assays for detection of these pathogens.

Volatile fatty acids (VFAs) play a role in suppression of plant pathogens during anaerobic soil disinfestation (ASD), but it is unclear how VFAs in anaerobic soil affect Athelia rolfsii (formerly Sclerotium rolfsii). Anaerobic growth chamber trials were conducted to evaluate effects of VFA and VFA concentration, and interactions with soil pH and soil texture, on A. rolfsii sclerotia viability (as indicated by sclerotia germination) and colonization by potential mycoparasites. In the first objective, sclerotia were exposed to acetic or n-butyric acids at 4, 8, or 16 mmol/kg soil in sandy soil; soil pH was buffered to 5, 6, or 7. Sclerotial germination was generally reduced by both VFAs, notably at pH 5 (29% germination at 4 mmol/kg soil, 1% at 8 mmol/kg soil, and 0% at 16 mmol/kg soil). The highest colonization rates were observed in acetic acid at 16 mmol/kg soil and soil pH of 5 and 6 (65 and 55% colonization). Sclerotial germination in water or HCl controls was consistently above 90%, with minimal colonization. In the second objective, sclerotia in sandy or sandy loam soil were exposed to 4 or 16 mmol VFA/kg soil at soil pH 5 or 6. Sclerotial germination was generally less in sandy soil compared to sandy loam soil (e.g., 4 mmol VFA/kg soil at pH 5, 62% germination in sandy loam versus 0% in sandy soil), but not at pH 5 and 16 mmol/kg soil (< 1% germination in both soil textures). Soil colloid (clay and organic matter) concentration likely plays a role in reduction of VFA activity. VFAs are probable important factors in A. rolfsii suppression due to ASD treatment in many soil environments, and activity is dependent on VFA concentration, soil solution pH, and soil texture.

Pomegranate (Punica granatum) is an important source of bioactive compounds and has been used in folk medicine for many centuries. This paper describes the in vitro antifungal activity of pomegranate peel aqueous extract (pae) on the development of Fusarium wilt of tomato caused by Fusarium oxysporum, f. sp. lycopersici. HPLC-DAD-ESI/MS analysis was performed to identify punicalagins and ellagic acid, which are the main antifungal compounds. In vivo tests established the efficacy of pae treatments in controlling Fusarium wilt by evaluating improvements in growth variables of tomato plants. At high concentrations, pae showed allelopathic activity in tomato plants. The germination and the radicle growth of tomato seeds were significantly affected by pae. Increasing the extract concentration led to a progressive decrease in germination and in the length of the radicle. The reduction of the Fusarium population in soil and the increase in number of healthy plants obtained as a result of pae treatments indicate that this plant extract could have an important role in biologically-based management strategies for the control of Fusarium wilt in tomato crops.