Australasian Plant Pathology最新文献

Fusarium oxysporum f. sp. albedinis, the causal agent of Bayoud disease, poses a serious threat to date palm (Phoenix dactylifera L.) cultivation. This study evaluated natural phenolic compounds from selected date palm cultivars as potential inhibitors of two proteins, 3-phytase and FGB1 (G-protein β subunit), and conducted a detailed analysis of their binding interactions. Seventeen phenolic compounds were retrieved from PubChem, energy-minimized, and docked onto AlphaFold-predicted structures of 3-phytase and FGB1 using AutoDock Vina v1.2.5. Binding affinities were ranked, and protein–ligand interactions were characterized with Discovery Studio Visualizer. Resveratrol exhibited the strongest affinity toward both proteins (− 7.12 kcal/mol with 3-phytase; − 7.30 kcal/mol with FGB1), forming multiple hydrogen bonds (SER389, ILE390, ARG191) and π–π stacking interactions that stabilized its binding within the active sites. Ferulic acid, p-coumaric acid, and sinapic acid also displayed favorable binding, mediated by hydrogen bonding and aromatic interactions. Comparative mapping highlighted target-specific preferences. Overall, the study supports the potential of phenolic metabolites as natural inhibitors against Bayoud disease, providing a foundation for developing environmentally sustainable control strategies for date palm cultivation.

Phytophthora meadii and P. palmivora are highly destructive plant pathogens, causing fruit and crown rot in arecanut and bud rot in coconut, respectively. In this study, we assembled and characterized the mitochondrial genomes of P. palmivora and P. meadii, analyzing their gene composition and structural organization. Additionally, we performed comparative analyses of mitochondrial genomes and investigated phylogenetic relationships among oomycete species. The complete mitochondrial genomes of P. palmivora (38,708 bp) and P. meadii (37,974 bp) were assembled, with coding regions accounting for approximately 74% and 72% of the total genome in P. palmivora and P. meadii, respectively, with G + C contents of 21.88% and 21.45%. Intergenic regions comprised approximately 11.3% of the P. palmivora mitogenome and 10.2% of the P. meadii mitogenome. While P. palmivora was predicted to encode 39 protein-coding genes (PCGs), P. meadii contained 37 PCGs. Both mitogenomes included two ribosomal RNA genes (rns and rnl) and 25 transfer RNA (tRNA) genes. Nucleotide composition analysis revealed a bias toward A/T over G/C. Phylogenomic analysis based on 34 protein-coding genes placed P. palmivora and P. meadii within the same clade, further supporting their close evolutionary relationship.

Lemon myrtle (Backhousia citriodora, F. Muell.) is a native Australian myrtaceous species, highly valued for its unique, citral-rich essential oil. The development and success of this Australian industry has been in jeopardy since the detection of myrtle rust (Austropuccinia psidii) in Australia (April 2010). Since the initial invasion, it has spread across the major lemon myrtle growing regions in New South Wales and Queensland. The main commercial clones are highly susceptible to infection, with plantations experiencing up to 70% production losses. To identify resistance to A. psidii for industry use, disease assessments were conducted on germplasm originating from 13 Queensland provenances, established in two clonal field trials. Newly collected germplasm from the Ubobo provenance was also screened under controlled conditions. Infection caused symptoms ranging from small, restricted sori on a low percentage of leaves, to infection on up to 100% of leaves, with distorted shoots and severe dieback on infected stems. No fully resistant germplasm was identified, but significant differences in observed disease offer opportunities to select more resistant clones than those currently relied on by the industry. Germplasm from Eumundi, Noosa and Woondum (southern Queensland), and Silver Valley (northern Queensland), showed superior resistance to A. psidii across assessments and trial sites. Substantial variation in plant growth traits of importance to commercial production (e.g. canopy structure and foliage density) was observed among the provenances, families, and clones evaluated across the trials, suggesting the need to consider plant growth, biomass yield and essential oil properties when selecting industry-suitable germplasm. Implementing a breeding or hybridisation program should be a priority for the industry.

Nelumbo nucifera, commonly known as the sacred lotus, has significant cultural, medicinal, and nutritional value as an aquatic plant in Vietnam. From 2022 to 2023, lotus plants in Hue City, Vietnam, exhibited symptoms of brown leaf blight. Initially, irregular light brown spots appeared on the leaves, which gradually expanded until the entire leaf turned dark brown and wilted. Based on morphological characteristics and DNA sequence data of three loci, the internal transcribed spacer (ITS), beta-tubulin (TUB2), and translation elongation factor 1-alpha (TEF1-α), supported by phylogenetic analysis, the pathogen was identified as Nigrospora lacticolonia. BLASTn analyses revealed 99.5–100% sequence similarity with N. lacticolonia accessions in GenBank. Multigene phylogenetic analysis based on a concatenated dataset of the three loci (ITS, TUB2, and TEF1-α) further clustered the isolates with N. lacticolonia, providing robust molecular support for this identification. Pathogenicity tests on whole plants grown under controlled conditions verified that the fungus was the causal agent of the disease, fulfilling Koch’s postulates. The disease incidence was approximately 91.67% (11/12) after 15 days post-inoculation, with an average lesion diameter of 121.27 ± 34.19 mm and an average lesion length to leaf length ratio of 75.40%. To our knowledge, this is the first report of brown leaf blight caused by N. lacticolonia on N. nucifera in Vietnam and worldwide. These findings provide new insights into fungal pathogens affecting lotus and highlight the importance of developing effective disease management strategies to mitigate the economic impact of this disease on lotus cultivation.

Citrus reticulata cv. Hongmeiren is widely cultivated in China. However, citrus gummosis poses a significant challenge to the commercial cultivation of Hongmeiren. In this study, the pathogenic fungus was identified as Diaporthe eres based on morphological characteristics, pathogenicity assay, and genes sequence analyses of ITS, EF1-α, and TUB. The optimal growth conditions for D. eres on potato dextrose agar (PDA) were found at 28 °C, pH 7.0, with sucrose as the carbon source and peptone as the nitrogen source. Among six tested fungicides, 50% thiophanate-methyl demonstrated the strongest inhibitory effect, with an EC₅₀ value of 5.36 µg mL^− 1. This study represents the first documented case of D. eres causing gummosis in Hongmeiren in China.

Nematode-trapping fungi (NTF) are unique soil inhabitants capable of capturing and killing nematodes through specialized trapping structures. Some NTF species also exhibit mycoparasitic behavior, suggesting a dual lifestyle with potential for broad-spectrum biological control. In the present study, nine NTF isolates from orchard soils of the Bundelkhand region, India, were evaluated for their nematophagous and mycoparasitic potential against Meloidogyne incognita, Anguina tritici and Rhizoctonia solani. Based on morphological and molecular characterization (ITS1–ITS4 sequencing), the isolates were identified as Arthrobotrys thaumasia isolates, A. musiformis, A. jinpingensis isolates, A. sphaeroides, A. conoides, Dactylellina phymatopaga and Drechslerella brochopaga. All isolates captured and killed juveniles of M. incognita and A. tritici using distinct trapping devices, while seven isolates exhibited hyphal coiling and parasitism on R. solani. D. brochopaga showed the highest predation against M. incognita (92.6%), whereas A. jinpingensis was most effective against A. tritici (84.33%). Among mycoparasitic fungi, A. thaumasia isolates showed the highest mycoparasitic potential, followed by A. musiformis, by forming hyphal coiling around R. solani. This study represents the first evidence of mycoparasitic potential in A. thaumasia isolates, A. jinpingensis isolates, A. musiformis, and A. sphaeroides. The findings highlight the dual ecological role of NTF as nematophagous and mycoparasitic fungi, underscoring their promise as eco-friendly biocontrol agents in integrated disease management systems.