Journal of Phytopathology最新文献

Melon is a major crop cultivated in the Brazilian Semiarid region. Several soilborne fungal pathogens cause root rot and vine decline (RRVD) in commercial production areas. This study evaluated the pathogenicity of Macrophomina pseudophaseolina isolates in melon accessions and characterised their differentially expressed protein profiles using sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS-PAGE). Two isolates differing in aggressiveness (CMM4807 and CMM4826) were inoculated into the moderately resistant accession C-14 and the susceptible accession MR-1 using the toothpick method. Protein extraction from stem and root tissues was performed using the phenol/SDS precipitation method, and quantified using the Bradford assay. Protein samples were analysed by SDS-PAGE. Root rot symptoms were observed in all inoculated melon seedlings, with the C-14 accession exhibiting moderate resistance to M. pseudophaseolina. Fewer differentially expressed protein bands were detected in the stem and root tissues of the C-14 accession when inoculated with the more aggressive isolate CMM4826. Accession C-14 exhibited moderate resistance to M. pseudophaseolina, a species associated with RRVD in melons. Protein analysis revealed differentially expressed bands after inoculation, with the number of bands influenced by the aggressiveness of the isolates, although both isolates were pathogenic. Further studies are necessary to identify these differentially expressed proteins and elucidate their functions in this plant–pathogen interaction.

The rapid expansion of cannabis production for medicinal purposes in South Africa has led to increasing concerns regarding the prevalence and impact of significant disease challenges, particularly with regard to fungal and Oomycetes pathogens. This study aimed to identify and confirm the pathogens causing wilting, yellowing and white and grey mould symptoms on cannabis. Samples were collected from an aeroponic cannabis facility. The resulting isolates were identified based on DNA sequence data from the rDNA-ITS and tef1-α loci, and the pathogens were confirmed as Botrytis cinerea, Fusarium oxysporum, Pythium myriotylum and Sclerotinia sclerotiorum. Pathogenicity trials further confirmed that all these species were capable of causing the observed symptoms on cannabis plants. Notably, this study represents the first report of these pathogens causing disease symptoms on cannabis in South Africa. These findings emphasise the need for proactive disease monitoring and the development of management practices, to minimise the impact of fungal pathogens on the growing cannabis industry in South Africa.

Datura innoxia, commonly known as ‘angel's trumpet’ or ‘devil's trumpet’, is an ornamental plant widely distributed and cultivated in Brazilian gardens. However, a stem rot was observed in garden plants in Curitiba, Paraná, Brazil. This study aimed to identify the causal agent of the disease through molecular characterisation, morphological characterisation and pathogenicity testing. The isolate CMRP7504 was obtained from internal fragments of diseased stems of D. innoxia. Molecular characterisation was performed using Maximum Likelihood (ML) and Bayesian Inference (BI) analyses of concatenated partial sequences of the G3PDH and HSP60 genes, in addition to the internal transcribed spacer (ITS). The DNA sequences of the pathogen clustered into a reliable clade identified as Sclerotinia sclerotiorum. Morphological characterisation matched the descriptions for S. sclerotiorum. Pathogenicity was assessed in potted plants inoculated with mycelial plugs of the isolated causal agent. Inoculated plants began to wilt on the 13th day, did not recover, and died after the 15th day post-inoculation. The fungus was re-isolated from lesions of inoculated plants and showed the same morphological characteristics as isolate CMRP7504. To the best of our knowledge, this is the first report of S. sclerotiorum causing stem rot in D. innoxia plants in Brazil.

Phytoplasmas were detected in potato tubers and sugar beet roots in neighbouring fields in Southern Germany using quantitative PCR. Infected potato plants showed phytoplasma-associated symptoms including yellowing, upward leaf rolling, aerial tubers and early senescence. Sugar beet plants showed similar symptoms to those of syndrome ‘basses richesses’ (SBR) disease, including proliferation, yellowing and necrosis of older leaves. The genetic diversity of the phytoplasmas in the symptomatic potato and sugar beet plants was investigated through sequence analysis of 16S rRNA and stamp, vmp1, tuf and secY genes. The RFLP profiles and sequences of 16S rRNA were identical among all the sugar beet-positive samples and aligned with subgroup 16SrXII-P, whereas the potato phytoplasma strains were identified as belonging to subgroup 16SrXII-A. Sequence analysis of the non-ribosomal genes showed that the potato strains belonged to the b1 group of the tuf gene, the V4 and V17 groups of the vmp1 gene and the secY3 and secY4 groups of the secY gene. However, the sugar beet strain was clearly distinct from the potato strains. Together with strain 916/22 from sugar beet in eastern Germany, they formed a new group of tuf, secY, vmp and stamp genes. RFLP assays and multilocus sequence analysis of non-ribosomal genes of the phytoplasma strains confirmed that the potato phytoplasma strains were molecularly different from the sugar beet phytoplasma strains. In addition, this is the first report on the multilocus sequence analysis of ‘Candidatus Phytoplasma solani’ strains in potato plants in Germany, suggesting differences in source plants other than sugar beet or interactions with insect vectors specific to each crop.

Nimbhore, P. P., Tiwari, R., Hazra, T., & Yadav, M. P. (2024). Classification of cotton crop disease using hybrid model and MDFC feature extraction method. Journal of Phytopathology, 172, e13324. https://doi.org/10.1111/jph.13324

In the above published article, the second affiliation for Padma P. Nimbhore was missed. The complete correspondence details should be as follows:

Correspondence

Padma P. Nimbhore, Research Scholar, Computer Science and Engineering, Indian Institute of Information Technology, Pune, Maharashtra, India

Assistant Professor, School of Computer Engineering, MIT Academy of Engineering, Pune, Maharashtra, India

Email: [email protected]; [email protected]

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In July 2021, desert rose plants were consistently observed with symptoms of brown spots on the leaves, which coalesced and promoted leaf fall. The causal agent of the disease was unknown. This study aimed to identify the pathogen responsible for the symptoms through morphological and molecular characterisation, as well as pathogenicity tests. The pathogens were identified as Colletotrichum siamense and a novel species of Lasiodiplodia representing the first report of these fungi causing leaf spot on desert rose in Brazil and worldwide.