Publications

4497

Citrus greening or Huanglongbing (HLB) is a rapidly spreading disease caused by Candidatus Liberibacter species, which inhabit the phloem of citrus plants. It is primarily transmitted by psyllid insects. Managing HLB is challenging due to the bacterium's phloem-restricted nature, making diagnosis and treatment with antimicrobials difficult. Here in the present study, the bacterial consensus sequences were used for the primer design with In silico approaches and validated by PCR. The study was carried out in the Malwa region of Madhya Pradesh, India, which is known for citrus cultivations and remains affected by the HLB disease. Phylogenetic analysis of 100 Candidatus Liberibacter 16S rRNA sequences from NCBI was conducted using MEGA 6, with Malwa-specific refinement via MAFFT alignment. Eight previously deposited sequences formed the basis for the study. A consensus sequence was derived and used to design region-specific primers with GeneFisher. PCR validation was carried out with standard thermal cycling and gel electrophoresis. Phylogenetic analysis of 100 Candidatus Liberibacter 16S rRNA sequences from NCBI was conducted using Phylogenetic analysis showed high genetic variation among Liberibacter strains, supporting the need for region-specific detection. Eight sequences from the Malwa region were aligned using BioEdit, confirming conserved primer sites. Consensus primers were designed using GeneFisher and optimized for 16S rRNA targets. PCR validation identified 22 positives out of 100 samples, with primer set 2 detecting all target species effectively. The study concludes that primer set 2 enables rapid and accurate detection of HLB-causing bacteria in the Malwa region.

Cyanobacteria biodiversity remains underexplored despite their ecological importance and potential applications. To address this, we investigated two Leptolyngbya-like strains, LEGE 07170 and LEGE 191244, collected from marine tide pools in Portugal and Morocco using polyphasic approach. Phylogenetic analyses indicates that the strains form a distinct clade with strong statistical support in the Oculatellales order. The 16S rRNA gene identity matrix shows that the maximum shared values with the phylogenetically closest genera Gansulinema, Kaiparowitsia, Shahulinema, Aerofilum and Thermoleptolyngbya is consistently below 94.5%. Morphologically, LEGE 07170 and LEGE 191244 are indistinguishable to each other. Both optical and TEM analyses showed vacuole-like structures at the cells cross-walls and this character morphologically distinguishes these strains from their phylogenetically related genera. The 16S–23S ITS secondary structures also differed the LEGE-CC strains from their closest related genera.

Abstract The presence of fastidious phytopathogenic bacteria ‘Candidatus Arsenophonus phytopathogenicus’ and ‘Candidatus Phytoplasma solani’ challenges sugar beet cultivation in Austria. Reptalus artemisiae (Becker, 1865) (referred before as Reptalus quinquecostatus sensu Holzinger et al. 2003) is the principal vector of ‘Ca. P. solani’ to sugar beet in Serbia, while Pentastiridius leporinus is the primary vector of ‘Ca. A. phytopathogenicus’ in western Europe and can also transmit ‘Ca. P. solani’. This study investigates the epidemiology of the associated diseases in Austrian sugar beet fields. An extensive survey in 2024 at 33 locations revealed significant spatial and temporal variability in cixiid populations, with R. artemisiae emerging as the predominant species. Transmission trials and field surveys confirmed R. artemisiae as a vector of ‘Ca. A. phytopathogenicus’ and ‘Ca. P. solani’ 16SrXII-P driving a disease outbreak in Nikitsch. The predominance of R. artemisiae in nearly all monitored fields suggests its significant role in the pathogens’ epidemiology on a broader scale in the Pannonian plain. Spatial and temporal variations in pathogen incidence in Austrian sugar beet mirror patterns in Serbia, driven by R. artemisiae. The co-occurrence of ‘Ca. A. phytopathogenicus’ and ‘Ca. P. solani’ 16SrXII-A and 16SrXII-P and their transmission by two vectors complicate disease management efforts.

AbstractPurple sulfur bacteria (PSB) of the family Chromatiaceae (Gammaproteobacteria) can perform chemo‐ and photo‐lithoautotrophy (through anoxygenic photosynthesis) in anoxic layers of freshwater stratified (including meromictic) lakes. This group has been extensively studied via physiological and ecological approaches, albeit their genomics has lagged behind. Here, we monitored a small, shallow, karstic lake, Lagunillo de Cardenillas, that developed a pink coloration throughout the whole water column and prevailed for ca. 2 years across seasons of the limnological cycle. Combining the study of physical/chemical parameters, amplicon sequencing, metagenomics, genomics, and microscopy, we observed this phenomenon was caused by blooms of a novel Thiocapsa species, which represented ca. 40% of the total microbial biomass of the lake's water column during the autumn/winter mixing period, and ca. 36% in the anoxic layers during spring/summer stratification. The dominance of this microbe was attributed to the high sulfur concentrations and biogeochemical features of the lake combined with various genomic footprints/abilities of this microbe to utilize different nutrient sources under anoxic and oxic/microaerophilic conditions. The latter included nitrogen (cyanate and ethanolamine hydrolysis, N fixation, dissimilatory nitrate reduction, ammonia assimilation, denitrification), carbon (anoxygenic photosynthesis and the presence of α‐carboxysomes and type IA RuBisCOs) and sulfur (dimethylsulfide [DMS] and thiosulfate oxidation, dimethylsulfoxide [DMSO] reduction). In addition, this novel species possessed genes for gas vesicle formation, anoxic/oxic respiration pathways, hydrogenases, oxic stress response, and a CRISPR‐Cas array. Thus, its extensive genomic repertoire helped explain its versatility and success in colonizing both the anoxic layers and the oxic/anoxic interphase in this lake.

Abstract Aim Candidatus Methanoperedens-related archaea have recently been identified as anaerobic methane oxidizers in paddy soils. Fertilization practices, including the application of inorganic and organic fertilizers (e.g. chicken manure), may significantly influence their community dynamics and the associated methane cycling processes. However, the comparative effects of inorganic and chicken manure fertilization on these archaeal community in paddy fields remain unclear. This study aimed to examine the diversity, community composition, and abundance of Methanoperedens-related archaea at three representative soil layers of 0–10, 20–30, and 40–50 cm under three fertilization treatments (no fertilizer, inorganic fertilizer, chicken manure fertilizer). Methods and results High-throughput sequencing revealed significant differences in community composition among treatments, while overall diversity showed minimal changes. Quantitative Polymerase Chain Reaction indicated that archaeal abundance under inorganic (2.3 × 106 copies g−1) and chicken manure fertilization (2.2 × 106 copies g−1) treatments was significantly greater than that under no fertilization (1.8 × 106 copies g−1) in upper 30 cm soils, with no significant difference at 40–50 cm depth. Inorganic fertilization more strongly promoted archaeal abundance, whereas chicken manure had a greater effect on community structure. Soil ammonium, nitrate, and organic carbon contents were significantly correlated with archaeal community patterns. Conclusion Both inorganic and organic fertilization can substantially influence the community structure and abundance of Methanoperedens-related archaea in paddy soils.