The fungal pathogen, Verticillium dahliae (V.), is a significant concern in agricultural settings. Verticillium wilt (VW), a serious fungal disease caused by dahliae, significantly impacts cotton yields due to biological stress. Cotton's resistance to VW is grounded in an extraordinarily complex mechanism, effectively constraining the breeding of resistant varieties. This limitation directly correlates to the absence of thorough, in-depth research. this website Through QTL mapping, a novel cytochrome P450 (CYP) gene linked to resistance against the non-defoliated strain of V. dahliae was previously discovered on chromosome D4 within Gossypium barbadense. Through cloning procedures in this study, the CYP gene on chromosome D4 was paired with its homologous gene on chromosome A4, and they were designated GbCYP72A1d and GbCYP72A1a, respectively, as dictated by their genomic locations and protein subfamily memberships. The V. dahliae and phytohormone-induced expression of the two GbCYP72A1 genes was inversely correlated with VW resistance in lines where the GbCYP72A1 genes were silenced, as the findings indicate. Transcriptome sequencing and pathway analysis of GbCYP72A1 genes showcased a significant role in disease resistance, specifically focusing on plant hormone signal transduction, plant-pathogen interaction, and the mitogen-activated protein kinase (MAPK) signaling. The intriguing discovery was that, while GbCYP72A1d and GbCYP72A1a exhibited high sequence similarity and both contributed to increased disease resistance in transgenic Arabidopsis, a disparity in their disease resistance capabilities was observed. A synaptic structure within the GbCYP72A1d protein's structure may be the underlying reason for this difference, according to the protein structure analysis. From the collected data, it appears that GbCYP72A1 genes are essential for plant survival and defense in the presence of VW.
Significant economic losses are a consequence of anthracnose, a disease of rubber trees, which is attributed to the presence of Colletotrichum. Still, the specific species of Colletotrichum that attack rubber trees in Yunnan Province, a major natural rubber-producing region of China, have not been the subject of intensive research. From rubber tree leaves showing anthracnose symptoms across numerous Yunnan plantations, 118 Colletotrichum strains were isolated. Following comparisons of phenotypic characteristics and ITS rDNA sequences, 80 representative strains were selected for additional phylogenetic analysis using eight loci (act, ApMat, cal, CHS-1, GAPDH, GS, his3, and tub2), which resulted in the determination of nine species. Rubber tree anthracnose in Yunnan's plantations was significantly influenced by the prevalence of Colletotrichum fructicola, C. siamense, and C. wanningense. C. karstii was significantly more prevalent than C. bannaense, C. brevisporum, C. jinpingense, C. mengdingense, and C. plurivorum. C. brevisporum and C. plurivorum are newly documented in China among these nine species, and two further species—C. mengdingense sp.—are novel to the global community. The C. acutatum species complex and the C. jinpingense species are intimately tied to November's environmental conditions. November's research encompassed the *C. gloeosporioides* species complex. To confirm their pathogenicity, each species was inoculated in vivo onto rubber tree leaves, employing Koch's postulates. this website This research illuminates the spatial distribution of Colletotrichum species associated with rubber anthracnose across representative Yunnan locations, vital for formulating appropriate quarantine strategies.
The pear leaf scorch disease (PLSD) afflicting pear trees in Taiwan is a result of the bacterial pathogen Xylella taiwanensis (Xt), which has very specific nutritional demands. Early leaf loss, a weakening of the tree, and a decrease in the amount and quality of fruit produced are all indicators of the disease's presence. Currently, there is no treatment that eradicates PLSD. The only method growers have to control the disease is through the use of propagation material free from pathogens, which depends on an early and accurate diagnosis of Xt. The available diagnostic approach for PLSD is confined to a single simplex PCR method at this time. Utilizing TaqMan quantitative PCR (qPCR) methodology, five primer-probe sets targeting Xt were developed to detect the Xt presence. Three conserved genomic regions, commonly utilized by PCR systems for bacterial pathogen identification, are the 16S rRNA gene (rrs), the intergenic transcribed region between 16S and 23S rRNA genes (16S-23S rRNA ITS), and the DNA gyrase gene (gyrB). A BLAST analysis incorporating whole genome sequences of 88 Xanthomonas campestris pv. strains was performed against the GenBank nr database. Comparative analysis of campestris (Xcc) strains, 147 X. fastidiosa (Xf) strains, and 32 Xt strains underscored the unique targeting capabilities of primer and probe sequences for Xt. Using DNA samples from pure cultures of two Xt strains, one Xf strain, one Xcc strain, and 140 plant samples sourced from 23 pear orchards in four Taiwanese counties, the PCR systems were subject to a comprehensive evaluation. In terms of detection sensitivity, PCR systems utilizing two copies of the rrs and 16S-23S rRNA ITS genes (Xt803-F/R, Xt731-F/R, and Xt16S-F/R) outperformed the two single-copy gyrB-based systems (XtgB1-F/R and XtgB2-F/R). Metagenomic examination of a PLSD leaf specimen uncovered non-Xt proteobacteria and fungal pathogens. These findings demand careful consideration within PLSD practices, given their potential to hinder diagnostic procedures.
A dicotyledonous plant, Dioscorea alata, is a vegetatively propagated tuberous food crop which is either annual or perennial, according to Mondo et al. (2021). During 2021, D. alata plants at a plantation in Changsha, Hunan Province, China (28°18′N; 113°08′E) exhibited leaf anthracnose symptoms. On leaf surfaces or margins, the initial symptoms appeared as small, brown, water-soaked spots, subsequently escalating to irregular, dark brown or black necrotic lesions, marked by a lighter center and a darker rim. Later in the leaf's development, lesions spread over a majority of the surface, causing leaf scorch or wilting. Almost 40 percent of the plants that were in the survey cohort contracted the infection. Pieces of diseased leaf tissue were carefully collected from the junction of the healthy and diseased areas. The specimens were sterilized in 70% ethanol for 10 seconds and then submerged in 0.1% HgCl2 for 40 seconds, rinsed with sterile water three times, and placed on potato dextrose agar (PDA) for five days at 26°C in the dark. Ten plants were each observed to harbor 10 fungal isolates, featuring consistent morphological colony profiles. The PDA colonies, characterized by their initial white, fluffy hyphae, later matured into a spectrum of light to dark gray colors, revealing subtle concentric rings. Rounded at both ends, the hyaline, aseptate conidia were cylindrical, and their dimensions ranged from 1136 to 1767 µm in length and 345 to 59 µm in width, based on 50 specimens. Appressoria, characterized by their dark brown, ovate, globose form, measured 637 to 755 micrometers and 1011 to 123 micrometers. The Colletotrichum gloeosporioides species complex's morphology aligns with the descriptions of the species complex provided by Weir et al. in 2012. this website Amplification and sequencing of the internal transcribed spacer (ITS) region of rDNA and partial sequences of the actin (ACT), chitin synthase (CHS-1), and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) genes from isolate Cs-8-5-1 were performed using the primer sets ITS1/ITS4, ACT-512F/ACT-783R, CHS-79F/CHS-354R, and GDF/GDR, respectively, as outlined in Weir et al. (2012). Deposited in GenBank, these sequences were allocated accession numbers (accession nos.). OM439575 is the code assigned to ITS; OM459820 represents ACT; OM459821 is assigned to CHS-1; and OM459822 is the code associated with GAPDH. A BLASTn analysis of sequences against C. siamense strains revealed sequence identities ranging from a minimum of 99.59% up to 100%. A phylogenetic tree, derived via maximum likelihood from concatenated ITS, ACT, CHS-1, and GAPDH sequences, was constructed using MEGA 6. The Cs-8-5-1 strain demonstrated a 98% bootstrap consensus for its clustering with the C. siamense strain, CBS 132456. To investigate pathogenicity, a 10⁵ spores/mL conidia suspension was made from conidia collected from 7-day-old *D. alata* cultures grown on PDA agar. This suspension was then applied to the leaves of potted *D. alata* plants, 8 droplets per leaf, using 10 µL per droplet. Sterile-water-treated leaves were used as controls. Plants that were inoculated were placed in humid chambers, regulated to 26°C, 90% humidity, and a 12-hour photoperiod. The pathogenicity tests, each performed twice, involved three replicates of each plant. After a week of inoculation, the inoculated leaves demonstrated brown necrosis, resembling the necrosis observed in the field, contrasting with the healthy appearance of the control leaves. Specifically re-isolated and identified through morphological and molecular procedures, the fungus fulfilled the conditions of Koch's postulates. This is the first documented instance, within our knowledge base, of C. siamense being responsible for anthracnose infection on D. alata in China. Should this disease negatively impact the photosynthetic processes of plants, subsequently affecting their yield, preventative and management strategies should be implemented to mitigate the situation. Determining the nature of this pathogen will form the foundation for diagnosing and controlling the spread of this disease.
The understory environment supports the growth of the perennial herbaceous American ginseng plant, Panax quinquefolius L. The Convention on International Trade in Endangered Species of Wild Fauna and Flora (McGraw et al., 2013) classified it as a vulnerable species. Symptoms of leaf spot were evident on a six-year-old American ginseng crop grown in a research plot (eight by twelve feet) situated beneath a tree canopy in Rutherford County, Tennessee, during July 2021 (Figure 1a). The symptomatic leaves showcased light brown leaf spots, featuring chlorotic halos. These spots, predominantly within or bordered by veins, ranged in diameter from 0.5 to 0.8 centimeters.