On Cucurbita pepo L. var. plants, blossom blight, abortion, and soft rot of fruits were evident in December 2022. Zucchini plants, grown in Mexican greenhouses, are subjected to an environment with temperatures regulated from 10 to 32 degrees Celsius and a relative humidity that can go up to 90%. In roughly 50 plants examined, the incidence of the disease was about 70%, displaying a severity nearing 90%. A pattern of mycelial growth, marked by brown sporangiophores, was noticed on flower petals and rotting fruit. Using a 1% sodium hypochlorite solution for five minutes, ten fruit tissues were disinfected, then rinsed twice in distilled water. The lesion-edge tissues were inoculated into potato dextrose agar (PDA) media with lactic acid. Morphological analysis was subsequently conducted using V8 agar medium. Forty-eight hours of growth at 27 degrees Celsius yielded colonies that were pale yellow in color, with a diffuse cottony texture from non-septate, hyaline mycelia. These mycelia generated both sporangiophores bearing sporangiola and sporangia. With longitudinal striations evident on their surfaces, the sporangiola were brown and had dimensions ranging from ellipsoid to ovoid, measuring 227 to 405 (298) micrometers in length and 1608 to 219 (145) micrometers in width, respectively (n=100). Subglobose sporangia, having diameters of 1272 to 28109 micrometers (n=50) in the year 2017, contained ovoid sporangiospores. These sporangiospores, measuring 265-631 (average 467) micrometers in length and 2007-347 (average 263) micrometers in width (n=100), displayed hyaline appendages at their extremities. Considering these distinguishing characteristics, the fungus was identified as Choanephora cucurbitarum, in accordance with Ji-Hyun et al.'s (2016) findings. For molecular characterization of two representative strains (CCCFMx01 and CCCFMx02), the internal transcribed spacer (ITS) and large subunit rRNA 28S (LSU) regions were amplified and sequenced using ITS1-ITS4 and NL1-LR3 primer pairs respectively, according to the methodologies described by White et al. (1990) and Vilgalys and Hester (1990). In the GenBank database, both strains' ITS and LSU sequences were lodged, corresponding to accession numbers OQ269823-24 and OQ269827-28, respectively. A 99.84% to 100% identity match was observed in the Blast alignment between the reference sequence and Choanephora cucurbitarum strains JPC1 (MH041502, MH041504), CCUB1293 (MN897836), PLR2 (OL790293), and CBS 17876 (JN206235, MT523842), according to the Blast alignment results. Employing the Maximum Likelihood method and the Tamura-Nei model within MEGA11 software, evolutionary analyses were undertaken on concatenated ITS and LSU sequences from C. cucurbitarum and other mucoralean species to confirm species identification. To demonstrate the pathogenicity test, five surface-sterilized zucchini fruits were inoculated at two sites per fruit (20 µL each) with a sporangiospore suspension (1 x 10⁵ esp/mL) prior to wounding each site with a sterile needle. Fruit control necessitated the utilization of 20 liters of sterile water. Three days after inoculation in a humid environment set at 27°C, the growth of white mycelia and sporangiola manifested itself together with a soaked lesion. No instances of damage were seen on the control fruits. Reisolated from lesions on PDA and V8 medium, C. cucurbitarum was morphologically characterized, thus fulfilling Koch's postulates. Zerjav and Schroers (2019) and Emmanuel et al. (2021) documented the occurrence of blossom blight, abortion, and soft rot of fruits on Cucurbita pepo and C. moschata in Slovenia and Sri Lanka, which were linked to infections by C. cucurbitarum. Kumar et al. (2022) and Ryu et al. (2022) document this pathogen's capacity to infect a substantial diversity of plants across the globe. Mexican agricultural records show no losses due to C. cucurbitarum, and this report details the first instance of this fungus causing disease in Cucurbita pepo. Nevertheless, its presence in soil from papaya plantations indicates its importance as a potential plant pathogen. Consequently, implementing strategies to manage their spread is strongly advised to prevent the disease's propagation (Cruz-Lachica et al., 2018).
Shaoguan, Guangdong Province, China, observed a Fusarium tobacco root rot outbreak spanning from March to June 2022, affecting about 15% of its tobacco production fields, with a prevalence of disease incidence between 24% and 66%. At the outset, the lower foliage exhibited chlorosis, while the roots turned black. As the plants matured, the leaves turned brown and shriveled, the root tissues fragmented and fell away, leaving a few remaining roots. All life in the plant, in the course of time, concluded with the plant's full extinction. Pathological examination of six plant samples (cultivar unspecified) revealed disease. Test materials were sourced from the Yueyan 97 location within Shaoguan, geographically positioned at 113.8 degrees east longitude and 24.8 degrees north latitude. A 44-millimeter section of diseased root tissue was surface-sterilized in 75% ethanol for 30 seconds, followed by 2% sodium hypochlorite for 10 minutes. The tissue was then rinsed three times with sterile water and incubated on potato dextrose agar (PDA) medium at 25°C for four days. Fungal colonies were then subcultured onto fresh PDA plates, grown for five days, and purified via single-spore isolation. Eleven isolates, displaying similar morphological characteristics, were obtained. White, fluffy colonies dotted the culture plates, which exhibited a pale pink coloration on the bottom after five days of incubation. The slender, slightly curved macroconidia, measuring 1854 to 4585 m235 to 384 m (n=50), possessed 3 to 5 septa. Microconidia, either oval or spindle-shaped, contained one or two cells, and their dimensions ranged from 556 to 1676 m232 to 386 m (n=50). Chlamydospores failed to appear. According to Booth (1971), the presented characteristics are distinctive of the Fusarium genus. The SGF36 isolate was chosen as the subject of a more extensive molecular analysis. Amplification processes were applied to the TEF-1 and -tubulin genes, as noted in the research of Pedrozo et al. (2015). A phylogenetic tree, constructed using a neighbor-joining approach supported by 1000 bootstrap replicates, and derived from multiple alignments of concatenated sequences of two genes from 18 Fusarium species, placed SGF36 within a clade including Fusarium fujikuroi strain 12-1 (MK4432681/MK4432671) and F. fujikuroi isolate BJ-1 (MH2637361/MH2637371). In order to definitively identify the isolate, five additional gene sequences—rDNA-ITS (OP8628071), RPB2, histone 3, calmodulin, and mitochondrial small subunit—drawn from Pedrozo et al. (2015)—underwent BLAST searches within the GenBank repository. The outcomes suggested the isolate's strongest genetic similarity lay with F. fujikuroi sequences, exhibiting sequence identities exceeding 99%. Phylogenetic analysis of six gene sequences, excluding the mitochondrial small subunit gene, demonstrated that SGF36 clustered together with four strains of F. fujikuroi, producing a single clade. The pathogenicity of the fungi was established via the inoculation of wheat grains within potted tobacco plants. Sterilized wheat grains were inoculated with the SGF36 isolate and then incubated at 25 degrees Celsius for a period of seven days. intestinal immune system Into 200 grams of sterilized soil, thirty wheat grains, tainted with fungi, were carefully introduced, mixed thoroughly, and then placed within pots. A six-leaf-stage tobacco seedling (cultivar cv.), one such plant, was observed. Every pot contained a yueyan 97 plant. Treatment was administered to a total of 20 tobacco seedlings. Twenty further control saplings were given wheat kernels that were free from fungi. With the precision of a controlled environment, the seedlings were placed in a greenhouse, maintaining a temperature of 25 degrees Celsius and a relative humidity of 90 percent. After five days, seedlings that were inoculated displayed yellowing of the leaves and discolored roots. The control subjects' symptoms remained absent. Based on the TEF-1 gene sequence analysis, the fungus reisolated from symptomatic roots was identified as F. fujikuroi. No F. fujikuroi isolates were obtained from the control plants. Previous reports have linked F. fujikuroi to rice bakanae disease (Ram et al., 2018), soybean root rot (Zhao et al., 2020), and cotton seedling wilt (Zhu et al., 2020). We are aware of no prior reports that have documented the link between F. fujikuroi and root wilt disease in tobacco in China, as observed in this case. Determining the causative agent of the disease could lead to the implementation of effective control measures.
As documented by He et al. (2005), Rubus cochinchinensis, a crucial part of traditional Chinese medicine, serves a function in treating conditions like rheumatic arthralgia, bruises, and lumbocrural pain. The observation of yellow leaves from the R. cochinchinensis species occurred in Tunchang City, Hainan Province, a tropical Chinese island, in January 2022. The leaf veins, maintaining their verdant hue, contrasted with the chlorosis that propagated along the vascular tissue (Figure 1). Additionally, the foliage had contracted slightly, and the energy of the growth process was low (Figure 1). From our survey, we ascertained the incidence rate for this disease to be approximately 30%. immune system Three etiolated and three healthy samples, both weighing 0.1 gram each, were used for the extraction of total DNA, employing the TIANGEN plant genomic DNA extraction kit. A nested PCR methodology employed phytoplasma universal primers, P1/P7 (Schneider et al., 1995) and R16F2n/R16R2 (Lee et al., 1993), to achieve amplification of the phytoplasma's 16S ribosomal DNA. selleck chemicals llc The amplification of the rp gene was carried out using primers rp F1/R1 (Lee et al. 1998) and rp F2/R2 (Martini et al. 2007). While the 16S rDNA and rp gene fragments amplified successfully from three etiolated leaf samples, no amplification was noted from the healthy specimens. The cloning and amplification of fragments produced sequences that were subsequently assembled using DNASTAR11. Analysis of the 16S rDNA and rp gene sequences, obtained by sequence alignment, revealed no variation among the three etiolated leaf samples.