Publications

4544

Abstract ‘Candidatus Mycoplasma haemolamae’ (CMhl) is a hemotropic bacterium infecting South American Camelids (SAC), whose epidemiology and clinical significance are still not fully elucidated. This study investigated CMhl by qPCR in blood samples of alpacas ( Vicugna pacos ) and llamas ( Lama glama ) in Italy in 2021–2024, characterizing CMhl haplotypes based on partial 16 S rRNA sequences and defining haematological findings in a subset of CMhl-infected animals. Statistical analysis was performed to detect potential risk factors associated with CMhl positivity. Out of 206 animals (200 alpacas and 6 llamas), CMhl was detected by qPCR in 88 (42.7%) animals. CMhl haplotype #1 and #2 were detected in 42.2% and 0.5% of the animals, respectively. Binary logistic regression analysis showed that higher CMhl positivity was significantly associated with larger herd size ( P  = 0.011), Northern Italy area of origin ( P  = 0.031) and warmer seasons ( P  = 0.003). The detection of two CMhl haplotypes confirms the high diffusion of CMhl in SAC farmed in Italy. Results confirm that CMhl usually causes subclinical infections, suggesting that antimicrobial treatment is likely not necessary based on qPCR positivity alone. Results focusing on the association of CMhl positivity with warm temperatures and large herd size suggest the need of further studies on the genetic features, epidemiology and immune response in CMhl-positive SAC from Italy, with emphasis on understanding potential vector transmission.

Persian lime (Citrus latifolia Tan.) is a crop of high economic and social relevance in Mexico due to its nutritional properties, associated health benefits, and particularly the foreign exchange generated through exportation. In recent years, the state of Veracruz has become the leading production region for this species at the national level. However, this crop is susceptible to several vascular diseases that cause significant economic losses in the citrus industry. Among these, Huanglongbing (HLB) is considered the most destructive disease, exerting the greatest impact on Persian lime production. This study involved the collection of Persian lime leaf tissues from different sources: field-grown plants, certified nursery plants, and plants previously sanitized through micrografting and thermotherapy processes. Genomic DNA was extracted from the collected samples. DNA integrity was verified by agarose gel electrophoresis and quantified using a NanoDrop One-C spectrophotometer. Quantitative Real-Time Polymerase PCR (qPCR) was performed using a QuantStudio One thermocycler and SYBR Green Master Mix as the fluorescent detection system. Samples were considered HLB-positive when the cycle threshold (Ct) value was below 35 during the quantification of Candidatus Liberibacter asiaticus. The results support the early, precise, and efficient detection of CLas by qPCR in Persian lime plants, thereby contributing to improved diagnostic and phytosanitary management strategies for this crop.

Shorea assamica is an evergreen to semi-evergreen tree in the family Dipterocarpaceae. It is widely distributed in China, India, Myanmar, Malaysia, Indonesia, the Philippines, and other regions. In China, it is found in western Yunnan and southeastern Tibet. The species is valued for its aromatic white resin, which serves as an important chemical raw material (Ang and Maruyama 1997). In May 2025, S. assamica trees exhibiting symptoms of witches'-broom disease and plexus bud disease were found at Mengmao, WanDing, Nongdao, Jiegao, and Jiexiang in RuiLi County (97°31′-98°02′ E, 23°38′-24°14′ N), Dehong Prefecture, Yunnan Province, China. Following disease onset, the overall growth of infected plants was significantly slower compared to healthy individuals. Infected plants exhibited excessive branching, shortened internodes, and a clustered growth symptom. Lateral buds on diseased tree frequently developed into abnormal twigs, with many buds forming dense clusters and only a few producing leaves. The disease was designated as S. assamica witches'-broom (SAWB). Across the seven surveyed areas, over 74% of trees displayed symptoms, while the disease incidence in nursery-cultivated seedlings was 66%. The disease was found to be spreading actively. A total of 56 samples were collected from seven areas, including 42 symptomatic plants and 14 asymptomatic plants. The lateral stem tissues of 30 samples were observed under a scanning electron microscope (Hitachi S-3000N). Spherical bodies were found in the phloem sieve cells of symptomatic plants. Total DNA was extracted from 56 plant samples using the CTAB method (Porebski et al. 1997) and subjected to nested PCR testing. Double-distilled water was used as negative control, and the DNA extracted from Dodonaea viscosa affected by D. viscosa witches’-broom disease was used as a positive control. Nested PCR was employed to amplify the pathogen’s 16S rRNA gene (Lee et al. 1993; Schneider et al. 1993), and 1.2 kb segment was produced (GenBank accessions: PZ025091, PZ025092, and PZ025093). PCR specific to the ribosomal protein (rp) gene yielded a segment of approximately 1.2 kb (Lee et al. 2003) (GenBank accessions: PZ028767, PZ028768, and PZ028769). The fragment size from 31 samples was consistent with the positive control, confirming the association of phytoplasma with the disease. A BLAST analysis of the 16S rRNA sequences of S. assamica witches’-broom phytoplasma showed that it shared 99.68% identity with that of Rice orange leaf phytoplasma (GenBank accession: JQ965690). The rp sequence shared 99.83% identity with that of Salix tetradenia witches'-broom phytoplasma (GenBank accession: KC117314). An analysis with iPhyClassifier (Zhao et al. 2013) showed that the virtual RFLP pattern derived from the 16S rDNA fragment of SAWB phytoplasma was identical (similarity coefficient 0.98) to the reference pattern of 16Sr group I, subgroup B (OY-M, GenBank accession AP006628). The SAWB phytoplasma is a variant of 16SrI-B. The phylogenetic tree was reconstructed based on 16S rRNA and rp gene sequences using MEGA (Tamura et al. 2013). The analysis was conducted using the neighbor-joining method with 1,000 replicates of bootstrap analysis. The results indicated that the SAWB phytoplasmas grouped into clades including phytoplasmas belonging to 16SrI-B and rpI-B, respectively. In addition, 1-year-old S. assamica were used for grafting assays in nursery, the twigs from infected S. assamica under natural conditions were used as a scion, and the phytoplasma was detected using nested PCR after grafting for 40 days. To the best of our knowledge, S. assamica is a new host of ‘Ca. P. asteris’-related strain (16SrI-B) in China. The newly emerged disease is a threat to S. assamica.

Abstract Deception Island fumaroles in Antarctica represent rare environments where extreme heat intersects with cryospheric and marine conditions, creating remarkable environmental gradients. From the near-boiling sediments, we reconstructed a high-quality metagenome-assembled genome (MAG) affiliated with the Pyrodictiaceae. Phylogenomic analyses revealed that this genome, proposed to represent Ca. Pyroantarcticum pellizari, forms a distinct lineage separated from known genera in the family. Functional annotation uncovered a versatile metabolic repertoire, including pathways for sulfur and nitrogen cycling, peptide and amino acid transport, and mixotrophic energy conservation. Stress-response systems such as reverse gyrase, thermosome, and small heat-shock proteins were complemented by lineage-specific genes related to membrane stability, metal detoxification, and Pyrodictiaceae-specific cannulae. These adaptations likely support survival under sharp temperature gradients, hydrogen sulfide emissions, and high metal concentrations at the volcanic–cryosphere–marine interface. Our findings expand the phylogenetic and ecological scope of Pyrodictiaceae, highlighting Antarctic marine volcanoes as unique refuges for hyperthermophiles and as valuable models for investigating life’s habitability under extreme temperatures.

Abstract Sulfoquinovose, a sulfonated sugar derived from the thylakoid membrane lipid sulfoquinovosyl diacylglycerol, is abundant in photosynthetic organisms and plays a key role in global sulfur cycling. Its degradation in nature is mediated by specialized bacteria, many of which rely on the enzyme sulfoquinovosidase (YihQ) to release sulfoquinovose from sulfoquinovosyl (diacyl)glycerol. Despite its ecological importance, the diversity and functional roles of sulfoquinovose-degrading microorganisms remain poorly characterized in natural environments. Here, we developed a yihQ-targeted amplicon sequencing approach to investigate the richness and distribution of SQ-degrading bacteria across selected environments. We revealed high richness of yihQ-containing microorganisms in the analyzed cow rumen samples, far exceeding that observed in human and mouse gut microbiomes, suggesting an important role of sulfoquinovose metabolism in ruminant digestion. Anoxic microcosm experiments with sulfoquinovose-amended rumen fluid revealed cooperative microbial degradation of sulfoquinovose to sulfide via isethionate cross-feeding. Amplicon sequencing and genome-resolved metagenomics and metatranscriptomics identified yet undescribed and uncultured sulfoquinovose-degrading taxa. Members of Caproiciproducens (Acutalibacteraceae), Candidatus Limivicinus (Oscillospiraceae), and Sphaerochaetaceae transcribed the isethionate-producing sulfo-transketolase pathway, whereas isethionate was likely respired by a Candidatus Mailhella bacterium (Desulfovibrionaceae). This study presents a functional gene-based assay for tracking environmental yihQ richness, highlights sulfoquinovose degradation as a central metabolic process in the cow rumen, describes previously unknown sulfoquinovose-metabolizing bacteria, and advances understanding of sulfur physiology in complex microbial communities.