Onion (Allium cepa L.) as a new host for 'Candidatus Arsenophonus phytopathogenicus' in Germany.

Onion (Allium cepa L.) is the most produced vegetable after tomato worldwide and is grown on about 15,000 ha in Germany. In Lampertheim, Hesse in southwest Germany (49°40'02.3"N, 8°26'00.0"E) bulbs of the cultivar 'Red Baron F1' were harvested in September 2023 in an apparently healthy state. Four months later some of the onions showed rotting symptoms, which could not be assigned to a known storage disease. At first, the bulbs became glassy, later they showed soft rot. They originated from a field located in a growing region severely affected by "Syndrome Basses Richesses" (SBR). 'Candidatus Arsenophonus phytopathogenicus' as well as 'Candidatus Phytoplasma solani' are associated with this disease in sugar beet (Gatineau et al. 2002). Moreover, 'Ca. A. phytopathogenicus' was recently reported in association of bacterial wilt and yellowing in potato (Behrmann et al. 2023). Both phloem-restricted bacteria are vectored by the polyphagous planthopper Pentastiridius leporinus (Therhaag et al. 2024), which is highly abundant in this region. To examine, if the unknown symptoms in onion might be related to the presence of these pathogens, DNA of 69 bulbs showing a different degree of softening were analyzed. The samples were tested for the presence of 'Ca. Phytoplasma solani' in a TaqMan assay (Behrmann et al. 2022). All showed negative results. To demonstrate the presence of 'Ca. A. phytopathogenicus', universal and genus-specific primers for the amplification of 16S rDNA and a real-time qPCR assay amplifying an hsp20 fragment were employed (Christensen et al. 2004, Zübert and Kube 2021). Two bulbs of the five positive samples were in an apparently healthy state, the other three showed light to moderate softening symptoms. The 16S rDNA fragments from two samples were sequenced on both strands and aligned. Both fragments were homologous. One fragment of 1474 bp fragment showing 100% homology to the 16S rDNA from SBR (accession no. AY057392) was submitted to GenBank (accession no. PP400342). Other taxa of 'Ca. Arsenophonus' showed 16S rDNA homologies of less than 99.3 %. To corroborate the finding onion samples were subjected to PCR reactions employing genus-specific primers for the conserved tufB, secY and manA gene, which had been derived from multiple alignments of 'Ca. A. spp' sequence submissions (Sela et al. 1989, Lee et al. 2010). The tufB, secY and manA primers amplified fragments of about 980 bp, 640 bp and 930 bp, respectively, from all previously positive samples. Samples which had been tested negative for 'Ca. P. phytopathogenicus' remained negative. Fragments from two accessions were sequenced and the sequences from both isolates were 100 % identical. A BLAST search of the partial tufB gene (acc. no. PP950434) showed 98.57 % sequence identity to a yet unnamed Arsenophonus endosymbiont (acc. no. OZ026540) and 91.85 to 91.83 % to 'Ca. A. nasoniae' and 'Ca. A. apicola', respectively. A similar result was obtained for the partial secY sequence (acc. no. PP950433). The manA sequence (acc. no. PP942231) was identical to a partial sequence of 'Ca. A. phytopathogenicus' strain HN (acc. no. OK335757) and 97.42 % to 'Ca. A. nasoniae and about 87 % to related Arsenophonus species. The finding of 'Ca. A. phytopathogenicus' in onion is novel and might indicate an expanding host range of vector and pathogen in the regional crop rotation. As a correlation between the pathogen and the soft rot symptom is unclear at present, further investigations are needed.

The complete genome of "Candidatus Phytoplasma fraxini" AshY1 from the ash yellows group.

The complete genome of "Candidatus Phytoplasma fraxini" AshY1, originating from Fraxinus americana in North America, was assembled using long reads from single-molecule real-time sequencing technology. The chromosome of 598 kb provides insights into the effector repertoire of a phytopathogenic bacterium from the 16SrVII phytoplasma group.

Pentastiridius leporinus (Linnaeus, 1761) as a Vector of Phloem-Restricted Pathogens on Potatoes: 'Candidatus Arsenophonus Phytopathogenicus' and 'Candidatus Phytoplasma Solani'.

In Germany, the phloem-sucking planthopper Pentastiridius leporinus (Hemiptera: Cixiidae) currently represents the epidemiological driver for the spread of the syndrome "Basses Richesses" in sugar beets, which results in a reduced sugar content and an economic loss for the farmers. This disease is associated with the γ-proteobacterium 'Candidatus Arsenophonus phytopathogenicus' and the Stolbur phytoplasma 'Candidatus Phytoplasma solani'. Recently, P. leporinus was found in potato fields in Germany and is associated with Stolbur-like symptoms in this crop. In this study, we confirmed that the vector completes its lifecycle on sugar beets as well as on potatoes when reared under controlled conditions. Transmission experiments with adults of this vector combined with molecular analyses showed, for the first time, that both pathogens are transmitted by this vector to potatoes. For an accurate assessment of the Ca. P. solani and Ca. A. phytopathogenicus titers in the vector and host plants, gBlocks derived from the hsp20- and 16S rRNA genes were employed, respectively. For Ca. P. solani, the limit of detection was determined in potato and sugar beet material. The results of this study will further the research on the epidemiology of the syndrome "Basses Richesses" and "Stolbur" diseases and the response of host plants and vector insects to both pathogens.

Cytotoxic diterpenoids from the roots of Salvia lachnocalyx

ABSTRACT Salvia lachnocalyx Hedge, Lamiaceae, is an endemic sage which grows naturally in the Fars Province of Iran. The phytochemical analyses of the roots of S. lachnocalyx led to the isolation of five known diterpenoids: ferruginol (1), taxodione (2), sahandinone (3), 4-dehydrosalvilimbinol (4) and labda-7,14-dien-13-ol (5). Their chemical structures were elucidated using one (1H and 13C) and two dimensional (COSY, HSQC and HMBC) NMR spectroscopic data as well as electron impact mass spectra. The cytotoxicity of the purified compounds was evaluated against three human cancer cell lines; MOLT-4 (acute lymphoblastic leukemia), HT-29 (colorectal adenocarcinoma) and MCF7 (breast adenocarcinoma) and all of the isolated compounds showed considerable cytotoxic activity against these cell lines. Compounds 2 and 3 (IC50 range: 0.41-3.87 µg/ml) with endocyclic α,β-unsaturated carbonyl functional group, exhibited the highest cytotoxic activities compared to the other compounds (IC50 range: 6.85-17.23 µg/ml). In conclusion, compounds 2 and 3 are presented as compounds that deserve further investigation of their biological activities.

Bioassay guided purification of cytotoxic natural products from a red alga Dichotomaria obtusata

ABSTRACT Different solvent extracts of Dichotomaria obtusata (J. Ellis & Solander) Lamark, Galaxauraceae, a red algae collected from the coast of Bushehr in the Persain Gulf, was investigated for its cytotoxic properties and chemical constituents. The fresh alga, after extraction with methanol and dichloromethane were combined and partitioned between water, dichloromethane and ethyl acetate. The above fractions were then tested against MOLT-4 (human lymphoblastic leukemia) cancer cell line. The IC50 values of the dichloromethane and ethyl acetate layers of the crude extract were 29.8 ± 3.1 and 30.6 ± 7.9 µg/ml against MOLT-4 cells, respectively, while the water layer showed a week activity with IC50 > 50 µg/ml. After fractionation of the active extracts using open column chromatography over silica gel and preparative thin layer chromatography purification, two terpenoid derived compounds, trans-phytol palmitate and γ-tocopherol were isolated from the dichloromethane and ethyl acetate extracts. The structures of the compounds were elucidated using different spectral data including 1H NMR, 13C NMR, HSQC, HMBC and EI-MS. The IC50 values of compounds trans-phytol palmitate, γ-tocopherol and an undetermined mixture of compounds (F-13-14) were determined as 43.4 ± 1.6, – and 20.3 ± 6.2 µg/ml against LS180 (human colon adenocarcinoma); 53.2 ± 9.3, >100 and 27.6 ± 6.9 µg/ml against MCF-7 (human breast adenocarcinoma) and 40.0 ± 4.1, 48.8 ± 1.8 and 15.9 ± 0.3 µg/ml against MOLT-4 cell lines, respectively, which were comparable to the IC50 values of standard anticancer agent, cisplatin against the same cell lines. The red algae collected from the Persian Gulf contained substances that could inhibit the growth of human cancer cell lines and may represent a natural source for the discovery of novel anticancer agents.