Search Results (7)

Diaporthe species are critical plant pathogens that contribute to a disease complex responsible for substantial yield losses in soybean production worldwide. However, reports on the primary Diaporthe species causing soybean stem blight and their sensitivity to various fungicides are scarce in China. In this study, a total of 46 D. longicolla strains were isolated and identified from diseased soybean stems and rots collected from 14 regions of Heilongjiang province in 2021 and 2022. Among the eight fungicides examined, fludioxonil, mefentrifluconazole, tebuconazole, and azoxystrobin demonstrated effective inhibition for D. longicolla, with EC₅₀ values < 0.3 µg/mL. Interestingly, the EC₅₀ values of D. longicolla to two succinate dehydrogenase inhibitors (SDHIs), pydiflumetofen and fluopyram, were 5.47 µg/mL and over 100 µg/mL, respectively. In molecular dynamics simulations, pydiflumetofen exhibited a smaller RMSD, while fluopyram had a higher binding free energy with Sdh proteins compared to pydiflumetofen. This difference may contribute to the higher activity of pydiflumetofen in D. longicolla. Further analysis of the electrostatic potential and structural conformations of the binding pocket revealed that pydiflumetofen formed more hydrophobic interactions with SdhC and SdhD and was positioned closer to the SdhD subunit. A mixture of fludioxonil and mefentrifluconazole at a ratio of 1:5, as well as fludioxonil and pydiflumetofen at a ratio of 1:5, exhibited synergistic effects. These findings demonstrated that several fungicides could be utilized to control Diaporthe stem blight, and the difference in binding affinity to the Sdh subunit impacts sensitivity to fluopyram and pydiflumetofen. Full article

Species of the genus Diaporthe have a mating-type system with the two mating types MAT1-1 and MAT1-2, like other ascomycetes. They can either be heterothallic, which means that any isolate only possesses one of the two mating types and needs a mating partner for sexual reproduction, or homothallic, which means that they possess both mating types and are self-fertile. For several Diaporthe species, no sexual reproduction has been observed so far. Using PCR with primers specific to the defining genes MAT1-1-1 and MAT1-2-1, we determined the mating types of 33 isolates of Diaporthe caulivora, D. eres, D. longicolla, and D. novem from central Europe. In addition, we partially sequenced the mating-type genes of 25 isolates. We found that different D. longicolla isolates either possess MAT1-1-1 or MAT1-2-1, making the species heterothallic, which is in contrast to previous studies and the general assumption that D. longicolla only reproduces asexually. D. eres and D. novem were also found to be heterothallic. Using genomic sequence information and re-sequencing of DNA and RNA, we identified the MAT1-1-1 gene in D. caulivora and present here the full sequence of the mating-type locus of this homothallic species. Finally, we used sequence information from MAT1-1-1 and MAT1-2-1, respectively, for improved phylogenetic resolution of our isolates. Full article

Diaporthe (anamorph: Phomopsis) species are endophytes or fungal pathogens for many different plant species. Soybean (Glycine max) can be infected by many different Diaporthe species; among them, D. caulivora and D. longicolla are responsible for the most significant damages. Diaporthe goulteri is a species that was only recently described and has so far been found on sunflower (Helianthus annuus) in Australia and an unknown host in Thailand. Here, we report isolation of D. goulteri from soybean in southern Germany, molecular species identification, and additional morphological description. We also show that D. goulteri can infect soybean and describe the symptoms we observed, both on the plant where the isolate came from and following artificial inoculation. Full article

Diaporthe longicolla (syn. Phomopsis longicolla) is an important seed-borne fungal pathogen and the primary cause of Phomopsis seed decay (PSD) in soybean. PSD is one of the most devastating seed diseases, reducing soybean seed quality and yield worldwide. As part of a genome sequencing project on the fungal Diaporthe–Phomopsis complex, draft genomes of eight D. longicolla isolates were sequenced and assembled. Sequences of mitochondrial genomes were extracted and analyzed. The circular mitochondrial genomes ranged from 52,534 bp to 58,280 bp long, with a mean GC content of 34%. A total of 14 core protein-coding genes, 23 tRNA, and 2 rRNA genes were identified. Introns were detected in the genes of atp6, cob, cox1, cox2, cox3, nad1, nad2, nad5, and rnl. Three isolates (PL7, PL10, and PL185E) had more introns than other isolates. Approximately 6.4% of the mitochondrial genomes consist of repetitive elements. Moreover, 48 single-nucleotide polymorphisms (SNPs) and were identified. The mitochondrial genome sequences of D. longicolla will be useful to further study the molecular basis of seed-borne pathogens causing seed diseases, investigate genetic variation among isolates, and develop improved control strategies for Phomopsis seed decay of soybean. Full article

Oxidative stress in soybean plants infected with Diaporthe isolates was evaluated in order to select (1) the least aggressive inoculation method, (2) to determine the most aggressive Diaporthe isolate, and (3) to determine the most tolerant soybean cultivar to this isolate. Based on the present malondialdehyde (MDA) content, the main end product of the lipid peroxidation process, and the biomarker for oxidative stress, the mycelium contact method was chosen as the least aggressive inoculation method, compared to the toothpick method and plug method. The activity of the antioxidant enzymes (superoxide–dismutase (SOD), catalase (CAT), and peroxidase (PX)), the reduced glutathione (GSH) content, and the level of lipid peroxidation (LP) were measured in soybean cv. Sava infected by five different Diaporthe species (DPM1F—D. aspalathi, DPC/KR19—D. caulivora, DPC004NY15—D. eres, 18-DIA-SOY-14—D. gulyae, and PL157A—D. longicolla). The most pathogenic Diaporthe species to cv. Sava was D. eres. The screening of the antioxidant enzymes activity in the leaves of 12 different soybean cultivars (Altona, Atlas, Capital, Chico, CX134, Favorit, Lakota, McCall, Morsoy, Strain, Rubin, and Victoria) infected with D. eres by the mycelium contact inoculation method showed that Capital, McCall, and Morsoy were the cultivars with the highest tolerance to D. eres, followed by Chico, Favorit, Lakota, and Rubin. The most sensitive cultivars were Atlas, CX134, Victoria, and Strain. Full article

Bacillus strains can produce various lipopeptides, known for their antifungal properties. This makes them attractive metabolites for applications in agriculture. Therefore, identification of productive wild-type strains is essential for the development of biopesticides. Bacillus velezensis FZB42 is a well-established strain for biocontrol of plant pathogens in agriculture. Here, we characterized an alternative strain, B. velezensis UTB96, that can produce higher amounts of all three major lipopeptide families, namely surfactin, fengycin, and iturin. UTB96 produces iturin A. Furthermore, UTB96 showed superior antifungal activity towards the soybean fungal pathogen Diaporthe longicolla compared to FZB42. Moreover, the additional provision of different amino acids for lipopeptide production in UTB96 was investigated. Lysine and alanine had stimulatory effects on the production of all three lipopeptide families, while supplementation of leucine, valine and isoleucine decreased the lipopeptide bioproduction. Using a 45-litre bioreactor system for upscaling in batch culture, lipopeptide titers of about 140 mg/L surfactin, 620 mg/L iturin A, and 45 mg/L fengycin were achieved. In conclusion, it becomes clear that B. velezensis UTB96 is a promising strain for further research application in the field of agricultural biological controls of fungal diseases. Full article

The chemical investigation of a methanol extract of the deep-sea-derived fungus Diaporthe longicolla FS429 led to the isolation of two novel diterpenoids longidiacids A and B (1 and 2), two new polyketides (3 and 4), two new cytochalasin analogues longichalasins A and B (6 and 8) and three known analogues 5, 7, 9. Their structures were elucidated through comprehensive spectroscopic analysis, while the absolute configurations were established by the comparison of the experimental and quantum chemical calculated ECD spectra. The structure of compound 7 was confirmed through X-ray diffraction for the first time. In the bioassays compound 8 exhibited antiproliferative effects against SF-268, with an IC₅₀ value of 16.44 μM. Moreover, compounds 1 and 8 were detected to inhibit 35.4% and 53.5% of enzyme activity of Mycobacterium tuberculosis protein tyrosine phosphatase B (MptpB) at a concentration of 50 μM. Full article