Publications

4416

ABSTRACT Candidatus Saccharimonadia is a class‐level lineage of ultrasmall bacteria within the phylum Minisyncoccota (formerly Candidate Phyla Radiation or Ca . Patescibacteria), commonly found in activated sludge processes treating municipal wastewater. In this study, we aimed to elucidate the metabolic potential of Ca . Saccharimonadia by using shotgun metagenomic sequencing combined with a filtration‐based size‐fractionation approach for activated sludge from five wastewater treatment plants. A total of 65 high‐quality metagenomic bins were recovered, belonging to four orders and 19 families of Ca . Saccharimonadia, including previously unreported lineages in activated sludge. These bins had small genomes (approximately 0.46–1.73 Mbp) with limited metabolic capabilities, indicating dependency on other microorganisms. Notably, the order Ca . Saccharimonadales retained a type IV secretion system and effector gene cluster for parasitic interactions with the hosts, suggesting that Ca . Saccharimonadales bacteria may exhibit a parasitic lifestyle. Co‐occurrence network analysis showed that members of the order Ca . Saccharimonadales were significantly correlated with multiple lineages, including Actinobacteriota , for which a parasitic relationship has been previously demonstrated. Our results shed light on the potential ecophysiology of the diverse members of Ca . Saccharimonadia, providing a comprehensive understanding of Ca . Saccharimonadia in activated sludge.

Abstract Pistachio ( Pistacia vera L.) is a vital crop for Türkiye's economy, occupying over 420 000 ha, primarily in south‐eastern Anatolia. In 2023, severe symptoms, such as curling, chlorosis and needle‐like leaf deformation, were observed on pistachio trees in Şanlıurfa Province. This prompted a molecular study of phytoplasma pathogens. A real‐time PCR targeting the 16SrDNA gene was used to analyse DNA from eight symptomatic and two asymptomatic trees. A phytoplasma was found in two symptomatic samples but not in asymptomatic controls. Positive samples were further analysed using nested PCR. One sequence with 99% identity to ‘ Candidatus Phytoplasma trifolii’ (16SrVI‐A subgroup) was found by bidirectional sequencing of PCR products. The identification of the phytoplasma was confirmed by a phylogenetic analysis showing the clustering of the UP 1 isolate with ‘ Ca. Phytoplasma trifolii’ reference strain and by a virtual RFLP analysis using 17 restrictions enzymes. This first report of ‘ Ca. Phytoplasma trifolii’ in pistachio in Türkiye highlights the presence of this phytoplasma in a key agricultural sector. Although no yield losses have been observed to date, broader surveys and monitoring of leafhopper vectors are necessary to assess the potential risk and implement timely management strategies.

Abstract Bactericera maculipennis (Crawford) and Bactericera cockerelli (Šulc) (Hemiptera: Triozidae) share hosts within the Solanaceae and Convolvulaceae (Solanales), and both are associated with “Candidatus Liberibacter solanacearum” (Lso). Lso, transmitted by B. cockerelli, causes diseases in solanaceous crops including zebra chip disease of potato. Up to 50% of B. maculipennis adults also harbor Lso, but transmission of Lso to plants by this psyllid has not been confirmed yet. The only documented field host of B. maculipennis in the Pacific Northwest is Convolvulus arvensis L. (Convolvulaceae) but diagnostic methods fail to detect Lso in leaves of this plant. It is therefore unclear how Lso persists within B. maculipennis populations. We surveyed species of Convolvulaceae and Solanaceae for B. maculipennis and report a widespread association between B. maculipennis and Lso throughout the western United States. Diagnostic polymerase chain reaction failed to detect Lso from leaves of C. arvensis yet readily detected Lso from stems where B. maculipennis nymphs tend to feed. Bactericera maculipennis transmitted Lso to species of Convolvulaceae in greenhouse experiments, confirming vector competency. We report high rates of Lso infection in populations of both B. maculipennis and B. cockerelli occurring on C. arvensis, but occurrence of B. cockerelli on C. arvensis was limited to autumn months only and with very low populations. Results suggest C. arvensis is a non-crop reservoir of Lso but do not suggest that B. maculipennis is a direct threat to solanaceous crops or that C. arvensis is a major source of Lso-infected B. cockerelli colonizing potato fields.