In Colombia, 456,270 ha are cultivated with Musa AAB (plantain subgroup) ‘Hartón’ and ‘Dominico Hartón’, with a production of 4,476,586 t and an average yield of 10.47 t/ha (Agronet 2026). Root lesion nematodes ( Pratylenchus spp.) have been reported from banana-growing regions in the departments of Magdalena and Antioquia, as well as from plantain-growing regions in the departments of Quindío, Caquetá, and Valle del Cauca (Zuñiga et al. 1979; Barriga and Cubillos 1980). Although Pratylenchus coffeae was reported in these studies, species identification was not supported by morphological, morphometric, or molecular characterization. Pratylenchus spp. populations ranging from 8,604 to 24,796 nematodes/100 cm³ of roots were recovered from symptomatic roots exhibiting reddish to black cortical lesions in several Musa AAB ‘Hartón’ and ‘Dominico Hartón’ plantations in the municipality of Puerto Salgar, Cundinamarca, Colombia, located in the Bajo Magdalena region (Díaz-Camacho and Guzmán-Piedrahita 2026). Morphological and morphometric analyses were conducted on 30 females and 30 males from a single population at the Nematology Laboratory of Universidad de Caldas. Female body length (n = 30) ranged from 617.3 to 792.7 μm (mean = 718 μm); stylet length from 17.2 to 19.3 μm (17.9 μm); a = 18.2-25.3; b = 4.3-6.3; c = 18.2-27.8; and V = 79.1-83.1. Male body length (n = 30) ranged from 512 to 610 μm (mean = 560.3 μm); stylet length from 16.4 to 18.3 μm (mean = 16.9 μm); a = 21.1-31.2; b = 4.4-5.7; c = 19.6-25.5; and spicule length from 13.7 to 21.9 μm (mean = 19.2 μm). These morphological and morphometric characteristics were consistent with the original description of Pratylenchus coffeae (Castillo and Vovlas 2007). Genomic DNA was extracted from a pooled sample of nematodes obtained from a pure culture established on carrot discs following Speijer and De Waele (1997) using the QIAGEN DNeasy Blood & Tissue Kit. Two overlapping fragments of the 28S rRNA gene were amplified using primer pairs D2A/D3B (Tenente et al. 2004) and PC11LSUF/PC11LSUR (Luambano et al. 2020), yielding PCR products of approximately 811 and 781 bp, respectively. The PCR products were purified, sequenced, deposited in GenBank (accessions PZ739058 and PZ739059), and compared with reference sequences using BLAST. The sequences shared 99.86–100% identity with P. coffeae isolates deposited in GenBank. Bayesian phylogenetic analysis of the overlapping 28S rDNA sequences consistently placed the Colombian population within the well-supported P. coffeae clade (PP = 1.00). To fulfill Koch’s postulates, the P. coffeae population described above was used in a greenhouse assay. Fifteen days after planting, 15 in vitro–propagated Musa AAB ‘Dominico Hartón’ plants were inoculated with 1,200 individuals of P. coffeae (females and males)/plant by drenching the soil surrounding the seedling roots with the nematode suspension. Fifteen additional plants received sterile water and served as the non-inoculated control. After 90 days, inoculated plants exhibited significant reductions ( P < 0.05) in root fresh weight (43.1%), shoot dry weight (36.0%), and corm fresh weight (56.0%) compared with the non-inoculated control. The reproduction factor (RF), calculated as the final nematode population divided by the initial nematode population (P f /P i ), was 29.3 in inoculated plants, whereas no nematodes were recovered from control plants. To our knowledge, this is the first confirmed report of P. coffeae infecting Musa AAB plantains 'Hartón' and 'Dominico Hartón' in Colombia, supported by morphological, morphometric, and molecular characterization and pathogenicity testing. This report provides a basis for further epidemiological studies and the development of integrated strategies aimed at reducing yield losses.
Lasiodiplodia ziziphi causes canker disease in jujube and other woody plants. Its control relies mainly on fungicides. Mycoviruses that cause hypovirulence are an emerging option for the biological control of fungal diseases. In this study, we identified a novel double-stranded RNA (dsRNA) mycovirus, Lasiodiplodia ziziphi partitivirus 1 (LzPV1), from L. ziziphi strain CDZM004. The LzPV1 genome consists of two dsRNA segments. dsRNA1 (1,905 bp) encodes an RNA-dependent RNA polymerase (RdRp), and dsRNA2 (1,773 bp) encodes a capsid protein (CP). The genome is packaged into isometric virions about 32 nm in diameter. Phylogenetic analysis of the RdRp and CP placed LzPV1 in the genus Alphapartitivirus of the family Partitiviridae. LzPV1 was transmitted horizontally through hyphal anastomosis and vertically through conidia. LzPV1 infection reduced the virulence of L. ziziphi, changed its hyphal morphology, and increased fungal sensitivity to the fungicide pyraclostrobin. This is the first mycovirus reported in L. ziziphi and the first partitivirus described in the genus Lasiodiplodia. LzPV1 is a promising biocontrol resource for jujube canker disease.
Powdery mildew, caused by Blumeria graminis f. sp. tritici (Bgt), severely impacts wheat production. The deployment of effective resistance genes through marker-assisted selection (MAS) provides an efficient strategy for sustainable management of this disease. In this study, the wheat breeding line N278 showed broad-spectrum resistance to all 24 Bgt isolates at the seedling stage and maintained resistance at the adult-plant stage for five consecutive years. Genetic analysis showed that the resistance was controlled by a single dominant gene, temporarily named PmN278. Bulked segregant RNA-Seq (BSR-Seq) in F2:3 families combined with large-scale molecular marker genotyping of 8,000 F3 individuals delimited the resistance locus to an 882.36 kb interval on chromosome arm 5BL according to Chinese Spring reference genome (v2.1). Sequence alignment and molecular marker detection indicated that the resistance locus identified in N278 corresponds to the previously cloned powdery mildew resistance gene Pm36, which encoded a tandem kinase with a transmembrane domain (WTK7-TM). Gene expression profiling revealed a significant induction of Pm36 transcripts at 48 hours post-inoculation (hpi) with Bgt isolate E09, corresponding to the early stage of fungal infection development in N278. Furthermore, MAS was used to transfer Pm36 into the susceptible commercial cultivar Shixin 828, generating the resistant advanced line NS24. Field evaluation over three consecutive growing seasons showed that NS24 retained stable powdery mildew resistance without obvious negative effects on major agronomic traits. These results validate the effectiveness of Pm36 in an elite Chinese wheat breeding background and provide valuable resources for the deployment of broad-spectrum powdery mildew resistance in wheat improvement.
Cotton production has long faced multiple-pathogen disease scenarios. These include disease complexes where multiple pathogens are involved, accelerating disease progression, altering symptom expression, and reducing the effectiveness of disease management options. These complexes include cotton root rot, vascular wilt, leaf spot, and boll rot. This Feature Article explores plant-pathogen and pathogen-pathogen interactions in cotton disease complexes and the factors that influence them. It also discusses advances in molecular diagnostics, such as pathogen assemblage profiling, which enables more accurate detection and measurement of co-infections, thereby improving risk evaluation and informing targeted disease management practices. Drawing on evidence from cotton-growing regions worldwide, particular attention is given to the relevance and implications of pathogen co-infection and disease complexes for Australian cotton production systems. Recognizing and managing pathogen co-infections and disease complexes, rather than addressing individual pathogens in isolation, provides a framework for more sustainable cotton production systems and enhances the ability to anticipate and respond to evolving crop health challenges under changing conditions driven by climate change, global trade, and agricultural intensification.
Burkholderia spp. are found in diverse ecological niches, including soil, water, and the rhizosphere of plants, the latter with which they exhibit pathogenic, non-pathogenic, and symbiotic interactions. Some Burkholderia species are known to cause slippery skin and sour skin diseases in onion. This study aimed to characterize the species of Burkholderia strains recovered from symptomatic onion bulbs and leaves in Pennsylvania (PA) and New York (NY) and assess their disease severity on pearl onion bulbs. A total of 89 Burkholderia strains were included, and their phylogenetic relationships were determined using recA gene sequences. Phylogenetic analysis identified five Burkholderia species and two Paraburkholderia species. Burkholderia cepacia and B. orbicola were predominant in NY, while B. gladioli was identified only in PA. Non-parametric statistical analyses comparing disease severity among Burkholderia strains by state (PA vs. NY) showed significant differences between PA and NY strains. Furthermore, ordinal logistic regression was conducted to evaluate how predictor variables (species, state, and isolation source) influence the probability of strains having higher or lower disease severity. This analysis indicated that state (PA vs. NY) was the only significant predictor of increased disease severity among PA strains may partly reflect differences in species composition between states. Local environmental conditions, region-specific cropping systems, and cultural practices could also influence disease severity, but their potential role require further investigation.
