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4467

Introducción: La Punta Morada de la Papa (PMP) es una de las enfermedades más graves que afectan al cultivo de la papa en diversos países de América y del mundo; Candidatus Liberibacter solanacearum (CaLso) es el agente causal de esta enfermedad que en los últimos años en el Ecuador ha sido causante de importantes pérdidas económicas. El manejo de la PMP está enfocado en el control del insecto vector Bactericera cockerelli a través de la aplicación periódica de insecticidas. Sin embargo, el uso de semilla proveniente de plantas enfermas puede también ser causante de la diseminación de la enfermedad. Objetivos: este estudio complementa las investigaciones que buscan establecer el porcentaje de transmisión de la enfermedad a través del uso de tubérculos-semilla provenientes de plantas con diferente sintomatología, causadas por CaLso en el cultivo de papa variedad Superchola. Metodología: se evaluó la transmisión de CaLso mediante la siembra de tubérculos-semilla provenientes de plantas con diferente sintomatología bajo condiciones controladas. Las plantas emergidas de estas semilas, fueron monitoreadas para detectar síntomas, recolectando muestras para ser analizadas mediante pruebas PCR. Los resultados permitieron estimar el porcentaje de transmisión a partir de tubérculos-semilla. La metodología aplicada, ayudó a determinar la viabilidad del patogeno en el material vegetativo y su potencial para establecer infecciones en una nueva generación de plantas. Resultados: de esta manera se encontró que el porcentaje de transmisión fue del 11.07% cuando se utiliza como semilla a los tubérculos provenientes de plantas con síntomas severos y si se utiliza semilla libre de la enfermedad, la transmisión es del 0.06 %. Conclusiones: se logró determinar una escala fenotípica según el grado de infección de la enfermedad en plantas progenitoras. Área de estudio general: Agronomía. Área de estudio específica: Sanidad Vegetal. Tipo de artículo: original.

Sunhemp (Crotalaria juncea L.) is a tropical leguminous crop valued for its multifaceted utility in fiber production, green manuring, and as a raw material in the manufacture of paper and rope. One of the major biotic stresses affecting sunhemp is phyllody disease, caused by a phytoplasma, specifically belonging to the “Candidatus Phytoplasma” spp. These are obligate intracellular pathogens classified under the class Mollicutes, and are primarily transmitted by sap-sucking insect vectors such as leafhoppers, and psyllids. Phyllody-infected plants exhibit a range of morphological abnormalities, including malformed floral structures, chlorosis, stunted growth, and proliferation of axillary shoots, resulting in significant agronomic losses. In the present study, the sunhemp genotype NTPSH 11-02 was subjected to gamma irradiation at doses of 20 kR, 30 kR, 40 kR, and 50 kR to induce genetic variability. The M₂ generation lines derived from these treatments were evaluated under natural field conditions to assess their resistance to phyllody. Out of 44 mutant genotypes, two genotypes, NTPSH 63 and NTPSH 32 exhibited moderate resistance to phyllody, while nine genotypes—NTPSH 24, NTPSH 31, NTPSH 36, NTPSH 39, NTPSH 41, NTPSH 48, NTPSH 53, NTPSH 56, and NTPSH 60 demonstrated a tolerant reaction under natural infestation. Phyllody infection was found to negatively impact key yield-contributing traits, including plant height, number of pods per plant, and 100-seed weight (test weight). A significant reduction in these parameters was observed in infected plants compared to healthy controls, underscoring the detrimental effect of phyllody on overall productivity and crop performance.

Black abalone Haliotis cracherodii from California, USA, and Baja California, Mexico, have faced massive population declines for more than 30 yr. The main factors contributing to these declines have been overfishing, pollution, climate change, and lethal diseases, such as withering syndrome, caused by the intracellular bacterium Candidatus Xenohaliotis californiensis (CXc). In recent years, the presence of an associated bacteriophage, pCXc, infecting CXc was detected and reported in some abalone species from California and Baja California. In the present study, 199 black abalone fecal samples from 14 sites along the Baja California coast were analyzed for the presence of CXc and pCXc DNA. The overall prevalence of bacteria and phage-infected bacteria was 44 and 38%, respectively. We found significant differences in the relationship between the prevalence and the mean lengths of abalone throughout the study area. This result is probably due to differences in the size-frequency distribution between sampling zones. The only site where we found a relationship between prevalence and length was in Isla Todos Santos. We did not see a relationship between abalone density and the prevalence of the bacteria and the phage. Additionally, we found a positive but non-significant correlation in prevalence between CXc and pCXc. This study is the first to detect the presence of pCXc DNA in wild populations of black abalone of Baja California.

Candidatus phytoplasma affects a wide range of host plants. In recent years, the severity and distribution of the disease have increase many fold. The present study isolated the pathogen from leaves (chlorosis), dried branches, and the other tissues of the infected tree. Acacia trees (n=15) showing severe yellowing and desiccation in the landscape areas of Şanlıurfa province were sampled from the buds (V-shaped) in three different parts of the branches, backward from the top of the branches during the flowering period, and from the middle veins of the leaves on the same branch during the leafing period. Samples were initially amplified using the universal primer pair R16F1/R16R0 and subsequently subjected to nested PCR with the primer pair R16F2n/R2. The results indicated that, on average, 2 out of 15 buds collected from the apical parts of the branches, 11 out of 15 from the middle, and 6 out of 15 from the basal parts were infected with ‘Candidatus Phytoplasma australasia’. Moreover, all samples collected from the midribs of these 15 trees were found to be infected with Ca. P. australasia.

A novel Gram-stain-negative, motile and thermo-halophilic rod-shaped bacterium SMD15-11T was isolated from Seokmodo hot spring in Incheon, Republic of Korea. The strain grew at concentrations of 0.5–7% (w/v) NaCl (optimum at 3%), at pH 5.0–9.0 (optimum at 7.0) and in a temperature range of 30–60 °C (optimum at 50 °C). Strain SMD15-11T shared the highest 16S rRNA gene sequence percentage with Hahella chejuensis 96CJ10356T (92.5%). Both the phylogenetic and phylogenomic analyses showed that strain SMD15-11T clustered with Hahellaceae members, demonstrating its close relatedness to the type species of the Hahellaceae family. The genome-relatedness indices between strain SMD15-11T and other type species of the family Hahellaceae were in the ranges of 67.2–69.1% for average nucleotide identity, 59.3–62.8% for average amino acid identity and 15.9–24.8% for digital DNA–DNA hybridization, which were significantly below the cut-off values for the genus delineation. The genome comprised 3,444,746 bp with a G+C content of 60.1 mol%. The polar lipids contained phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, four unidentified phospholipids, two unidentified aminophospholipids and two unidentified lipids. The predominant fatty acids are C16:1  ω9c, C16:0, C18:1  ω9c and summed feature 3, comprising C16:1  ω7c/C16: 1  ω6c. The polyphasic taxonomic properties indicate that the strain represents a novel genus and species in the family Hahellaceae for which the name Thermohahella caldifontis gen. nov., sp. nov. is proposed. The type strain is SMD15-11T (=KCTC 8289T=NBRC 116488T).

An anaerobic, thermophilic methanogen, designated strain LWZ-6T, was isolated from the Shengli oil field, China. The cells of strain LWZ-6T were non-motile cocci, with a diameter of 0.5–1.0 µm, and formed aggregates. They reduced methanol and monomethylamine into methane, using H2 as an electron donor. Dimethylamine, trimethylamine and methanethiol, H2/CO2, formate, acetate, pyruvate, lactate and glucose were not used as energy sources. Strain LWZ-6T required yeast extract, acetate or CO2 as carbon sources. Strain LWZ-6T grew at 35–65 °C (optimum 55 °C), pH 5.0–8.0 (optimum 6.0–6.5) and 0–60 g l−1 NaCl (optimum 9 g l−1). The genome was 1.54 Mbp with a G+C content of 54.42 mol%. Strain LWZ-6T shared 83.54% 16S rRNA gene sequence identity with Infirmifilum lucidum strain 3507LTT in the class Thermoprotei. Phylogenetic analysis based on the 16S rRNA gene, along with phylogenomic analysis, indicated that strain LWZ-6T belonged to the candidate class ‘Candidatus Methanomethylicia’, which lacks cultivated representatives. Based on these findings, a new species within a new genus, Methanosuratincola petrocarbonis gen. nov., sp. nov., is proposed for LWZ-6T (=CCAM 1872T=JCM 39528T). In addition, we propose the Methanosuratincolia class. nov. for candidate class ‘Ca. Methanomethylicia’ represented by Methanosuratincolaceae fam. nov. and Methanosuratincolales ord. nov. within the phylum Thermoproteota.