Journal of Phytopathology最新文献

Fusarium oxysporum f.sp. conglutinans (FOC) causes yellow wilt, a serious cabbage disease. This fungal species is composed of many strains within two pathotypes. In this study, the inhibitory effect of essential oils of six aromatic and medicinal plants (oregano, thyme, clove, cinnamon, lemongrass, litsea) at multiple concentrations on eight FOC isolates of different origins was investigated. Our results showed that oregano essential oil had the greatest inhibitory effect. The tested essential oils could be divided into three clusters according to the similar content of their main components (oregano and thyme, clove and cinnamon, lemongrass, and litsea), which correlated to some extent with their inhibitory effects on FOC. The tested isolates also differed in their response to the studied essential oils. The differences within FOC races were more important than between races, and the sensitivity of isolates against essential oils seemed to be more related to the geographical origin of the isolates, rather than to their race affiliation.

Yellow mosaic and leaf curl diseases caused by whitefly-transmitted begomo virus genera are important problems in tomato (Solanum lycopersicon L.) production in Indonesia, particularly on Java Island. The aims of this survey are to assess the percentages of disease incidence (DI) and disease severity index (DSI), evaluate the spread and complexity of begomovirus and crinivirus infections responsible for yellow mosaic and leaf curl diseases in tomato plants, and identify the species of whitefly insect vectors and their cryptic biotypes in tomato production centers located on Java Island, Indonesia. A total of 43 locations in East, Central, and West Java were surveyed during the dry season from July 2022 to September 2022. Disease incidence and severity were determined by observing 200 samples of tomato plants from five points at each location, with 40 plants per point of land. A total of 116 whitefly samples in microtubes and 215 symptomatic leaf samples were collected. The genus begomovirus and crinivirus infecting tomato were identified by PCR and RT-PCR using genus-specific primers. Similarly, whitefly species and their cryptic biotypes were identified by PCR using MCoI gene-specific primers. Results showed that DI and DSI remarkably differed between the lowlands (66%–89%) and highlands (33%–62%) in the provinces of Central Java and West Java. Furthermore, PCR analysis of 215 infected tomato showing the symptoms of yellow mosaic and curly leaf revealed that three begomoviruses, one crinivirus and their mixed combination both begomoviruses, one crinivirus has been detected in all the samples. Similarly, the whitefly insect vector Bemisia tabaci biotype Q was identified in all areas, whereas Trialeurodes vaporariorum was found only in the East Java and Java highlands, respectively.

Desmodium triflorum is an important gramineous forage grown in tropical regions of China. In August 2022, a new leaf spot disease was observed on D. triflorum during a field survey at the base of the Chinese Academy of Tropical Agricultural Sciences, Hainan, China. The pathogen was isolated and identified using morphological examination and phylogeny based on multi-gene sequences analysis of the nuclear ribosomal internal transcribed spacer, the second largest RNA polymerase subunit (RPB2), and beta-tubulin genes. The isolates were identified as Epicoccum sorghinum. The pathogenicity of E. sorghinum on D. triflorum was validated fulfilling Koch's postulates, causing leaf spot disease. To the best of our knowledge, this is the first report of leaf spot disease on D. triflorum caused by E. sorghinum in China.

Tobacco black shank (TBS) and tobacco root black rot (TRBR) are two of the most devastating tobacco soil-borne diseases that threaten sustainable tobacco planting. This study investigated the effects of Trichoderma sp. and a resistance inducer (RI) extracted from traditional Chinese medicine, individually or in combination, on the control of TBS and TRBR. The results showed that the application of Trichoderma sp. and RI, individually or in combination, significantly controlled the two soil-borne diseases by significantly affecting the bacterial, but not fungal, Shannon and Simpson diversity indexes. The disease indexes of TBS and TRBR in integrated application management were the lowest, resulting in the highest potassium contents in the tobacco leaves. The control efficacies of TBS and TRBR in the integrated application treatment were 71.52 ± 1.43% and 68.33 ± 0.69%, respectively. The integrated treatment altered the composition of the rhizosphere soil microbial community. The bacterial community, but not the fungal community, of the control treatment was separated from those of other treatments. The relative abundance of bacteria involved in chemoheterotrophy and fermentation in the control treatment increased, whereas that of bacteria involved in nitrification and aerobic ammonia oxidation decreased compared with the other treatments. Importantly, the application of Trichoderma sp. and RI, individually or in combination, clearly increased the relative abundance of saprotrophic fungi in contrast to the control treatment, while decreasing that of pathotrophic fungi. Our study suggests that a suitable integrated application of bioagents and RI has synergistic effects on the suppression of two tobacco soil-borne diseases by altering the rhizosphere microbiome composition in the field.

There is a paucity of information on the relationship between anthers and Type II expression of Fusarium Head Blight resistance (measured by point inoculation of a spikelet and observing disease spread over the wheat spike). Twenty-nine UK commercial wheat varieties were evaluated for the expression of Type II resistance. Anther extrusion was measured by counting the number of spikelets with anthers trapped between the lemma and palea (anthers trapped). In five spikelets where trapped anthers were not observed, the number of spikelets with anthers contained within the spikelet was counted (anthers retained). There was variation in expression in the expression of Type II resistance (p < .001), anthers trapped (p < .001) and anthers retained (p < .001). Anthers trapped and anthers retained were not correlated with each other, indicating both should be considered independently. Later maturity correlated with great resistance in the AHDB Type I resistance ratings but to greater susceptibility to point inoculations (Type II). Consistent with previous literature higher numbers of anthers trapped to increase susceptibility to FHB Type I. However, the relationships were reversed for the expression of resistance measured by point inoculation within the spikelet, where anthers trapped between the lemma and palea reduced susceptibility to Type II point inoculation (p < .01). This suggests a benefit of releasing some pollen from within the spikelet for this inoculation method. Similarly, anthers retained contributed to increased Type II susceptibility (p < .05), potentially providing substrates within the spikelet inoculation site aiding fungal growth, but correlated to greater Type I resistance (p < .05) indicating the anthers are hidden from initial infection on the outside of the spikelet, particularly under low infection pressure. While preliminary, this work suggests that variation in anthers trapped, anthers retained and maturity date may increase Type II expression of resistance and could relate to increased Type I FHB susceptibility.

The effects of the seed gall nematode ‘Anguina tritici’ (Steinbuch, 1799) on the agronomic characteristics of some bread wheat cultivars were investigated at the Trakya Agricultural Research Institute, Türkiye. An experiment was carried out in two different locations in Edirne in the 2019–2020 growing season. A total of 19 winter bread wheat cultivars were evaluated to assess infected grain number, healthy grain number, infected grain rate and yield. According to the results of the combined variance analysis, a statistically significant difference (p ≤ .01) was found in terms of yield from the application of inoculum. Compared to the control in wheat cultivars, there was a 52.15% decrease in the yield of infected parcels due to the damage of wheat seed gall nematode. The highest yield loss in infected parcels occurred in cv. Damla with 64.22% loss, while the least yield loss occurred in cv. Yüksel cultivar with 19%. Pathological symptoms, curling and twisting of the leaves, were not observed on green plants of cv. Yüksel cultivated in the field.

Apple rot disease, caused by Alternaria alternata, is causing significant losses in apple production, especially in post-harvest periods. Alternaria alternata, was isolated from rotten apple fruit of cv Amasya. Identification of the strain isolated from rotten apple fruit was made by ITS sequence and morphological analysis. In the present study, 58 different endophytic bacteria strains were isolated from apple fruit for use in apple rot disease control. Among the isolated strains, 26 endophyte strains were determined to inhibit the radial growth of mycelia of A. alternata in binary culture in PDA media. Based on 16S rRNA sequencing analysis, these antagonistic endophytic bacteria strains were identified as Bacillus ssp. Bacillus methylotrophicus (ib17) showed the highest significant inhibitory effect on the mycelial growth of A. alternata at a rate of 79.5% in PDA medium. The results of in vivo experiments showed that Bacillus licheniformis (ib20) achieved 100% biocontrol when endophyte bacterial strains were inoculated 24 h before the inoculation of A. alternata. When the three bacteria species and A. alternata were inoculated simultaneously, Bacillus myloliquefaciens (ib1), Bacillus licheniformis (ib21) and the Endophytic bacterium (ib16) showed the highest biocontrol efficacy against A. alternata at 81.8%. Furthermore, when the bacterial strains were inoculated at 24 h after inoculation of A. alternata, B. licheniformis (ib21) showed the highest biocontrol efficacy of 83.3% against the fungal pathogen compared to the controls. The endophytic bacterial strains produced fungal cell wall hydrolysing enzymes such as chitinase, cellulase, amylase and protease. According to the results of this study, apple endophytic bacteria are potential candidates to control apple decay caused by A. alternata through cell wall hydrolysing enzymes and reduce disease severity. However, the efficacy of the biological control was dependent on the applied time of epiphytic bacterial strains. Further research is needed on the biochemical mechanisms underlying the activity of these bacteria against A. alternata.

Tomato (Solanum lycopersicum) is a crucial vegetable globally, pivotal in securing the world's food supply. However, viral diseases pose a significant threat to tomato cultivation, resulting in considerable yield losses. Employing sensitive, rapid, and cost-effective detection methods is imperative for mitigating such losses in agricultural production. In response, we developed a Taqman® probe-based real-time multiplex PCR method capable of concurrently detecting three major plant viruses: Tomato brown rugose fruit virus (ToBRFV), tomato spotted wilt orthotospovirus (TSWV), and pepino mosaic virus (PepMV), all of which are prominent viral pathogens affecting tomato production. Utilizing envelope protein encoding sequences of these pathogens, we designed primers and probes, assigning the FAM reporter for ToBRFV, the HEX reporter for TSWV, and the Cy5 reporter for PepMV detection. The multiplex RT-qPCR experiment yielded successful results, with Ct values of 29.34, 25.93, and 27.47 for ToBRFV (at 10⁻⁶ dilution), TSWV (at 10⁻² dilution), and PepMV (at 10⁻³ dilution), respectively. Developed primers facilitate the early detection of destructive pathogens ToBRFV, TSWV, and PepMV using both RT-PCR and RT-qPCR, offering a user-friendly and cost-effective approach.

Nectria dematiosa exhibiting orange red colour perithecia on stems and branches of young and old apple trees were reported under field conditions during 2020 and 2021. Reddish discoloration followed by papery appearance of stem and branches were the characteristic symptoms observed. Ascomata were non-papillate, surface irregular comprising numerous cylindrical to narrowly clavate asci. Ascospores were ellipsoidal to fusiform, straight or slightly curved, hyaline with 0 to 1-septa. Richard and Royal Delicious variety of apple were more susceptible with moderate to high severity of the European canker. Based on nucleotide homology and phylogenetic analysis, the pathogen was confirmed as N. dematiosa (accession no. OQ152022). To the best of our knowledge, this is the first report of N. dematiosa causing European canker of apple in India.

Macadamia cultivation plays significant role in the economy of South Africa. Despite its importance, the industry grapples with disease-related challenges, notably flower blight, which threatens substantial economic losses by affecting yield and nut quality. In 2022, diagnostic services at the Agricultural Research Council and the Forestry and Agricultural Biotechnology Institute received macadamia flowers displaying blight symptoms. Employing two methods for fungal isolation, 25 isolates were obtained which were classified into one group based on morphological characteristics. DNA analysis identified the isolates as Botrytis cinerea. The pathogenicity testing was conducted on macadamia flowers to confirm Koch's postulates. This is the first report of B. cinerea affecting Macadamia integrifolia Maiden & Betche in South Africa, underlining its potential threat to the industry.