Facilitating Effects of Reductive Soil Disinfestation on Soil Health and Physiological Properties of Panax ginseng.

Chemical soil fumigation (CSF) and reductive soil disinfestation (RSD) have been proven to be effective agricultural strategies to improve soil quality, restructure microbial communities, and promote plant growth in soil degradation remediation. However, it is still unclear how RSD and CSF ensure soil and plant health by altering fungal communities. Field experiments were conducted to investigate the effects of CSF with chloropicrin, and RSD with animal feces on soil properties, fungal communities and functional composition, and plant physiological characteristics were evaluated. Results showed that RSD and CSF treatment improved soil properties, restructured fungal community composition and structure, enhanced fungal interactions and functions, and facilitated plant growth. There was a significant increase in OM, AN, and AP contents in the soil with both CSF and RSD treatments compared to CK. Meanwhile, compared with CK and CSF, RSD treatment significantly increased biocontrol Chaetomium relative abundance while reducing pathogenic Neonectria relative abundance, indicating that RSD has strong inhibition potential. Furthermore, the microbial network of RSD treatment was more complex and interconnected, and the functions of plant pathogens, and animal pathogen were decreased. Importantly, RSD treatment significantly increased plant SOD, CAT, POD activity, SP, Ca, Zn content, and decreased MDA, ABA, Mg, K, and Fe content. In summary, RSD treatment is more effective than CSF treatment, by stimulating the proliferation of probiotic communities to further enhance soil health and plant disease resistance.

Genome-Wide Analysis and Expression Profiling of the Glutathione Peroxidase-like Enzyme Gene Family in Solanum tuberosum.

Glutathione peroxidase-like enzyme is an important enzymatic antioxidant in plants. It is involved in scavenging reactive oxygen species, which can effectively prevent oxidative damage and improve resistance. GPXL has been studied in many plants but has not been reported in potatoes, the world's fourth-largest food crop. This study identified eight StGPXL genes in potatoes for the first time through genome-wide bioinformatics analysis and further studied the expression patterns of these genes using qRT-PCR. The results showed that the expression of StGPXL1 was significantly upregulated under high-temperature stress, indicating its involvement in potato defense against high-temperature stress, while the expression levels of StGPXL4 and StGPXL5 were significantly downregulated. The expression of StGPXL1, StGPXL2, StGPXL3, and StGPXL6 was significantly upregulated under drought stress, indicating their involvement in potato defense against drought stress. After MeJA hormone treatment, the expression level of StGPXL6 was significantly upregulated, indicating its involvement in the chemical defense mechanism of potatoes. The expression of all StGPXL genes is inhibited under biotic stress, which indicates that GPXL is a multifunctional gene family, which may endow plants with resistance to various stresses. This study will help deepen the understanding of the function of the potato GPXL gene family, provide comprehensive information for the further analysis of the molecular function of the potato GPXL gene family as well as a theoretical basis for potato molecular breeding.

First Report of Fusarium acuminatum Causing Leaf Spot on Schisandra chinensis in China.

Schisandra chinensis (Turcz.) Baill. is a popular and widely cultivated medicinal herb in China, which has rich nutritional value and medicinal effect. In August 2022, leaves with oval and irregularly circular light brown spots from 2 to 10 mm wide with white centers were found on Schisandra chinensis growing in Fusong district (127°28'E, 42°33'N) of Jilin, China. The symptoms were observed in 20% of the plants of a 2 ha-1 field of Schisandra chinensis. About 50% of the leaf areas were affected. As the disease developed, the lesions grew larger and developed necrotic centers. Leaves with light brown spot symptoms from five plants were collected from the field. Five leaf pieces (3 to 5 mm2) were excised from lesion margins, surface sterilized based on Ju et al. (Ju et al. 2021), and incubated on potato dextrose agar (PDA) at 25°C. Six single spores were isolated from five independently infected isolates for pure culture using the single spore isolation technique (Zhang. 2003). Representative single spore isolate (ZWWZH) was selected from pure cultures for further culture. After 5 days, fluffy white aerial mycelium with pink pigmentation on the underside of the colony were observed on PDA. Mycelia became pinkish-brown as the culture aged. Microscopic observations showed the presence of elongated or pointed, and thick-walled macroconidia (n = 50), predominantly three septate, 3.40 to 7.50 × 40.34 to 61.29 µm were observed. Chlamydospores formed in chains within or on top of the mycelium. The primers ITS1/ITS4 (White et al. 1990) and Bt-2a/Bt-2b (Robideau et al., 2011) were used to amplify the internal transcribed spacer (ITS) rDNA and ß-tubulin (TUB2) region, respectively. The obtained sequences were submitted to GenBank under accession numbers for OQ629789 (ITS) and OQ803521(TUB2). BLASTn analysis of both ITS sequence and TUB2 sequence, revealed 100% and 99.92% sequence identity with F. acuminatum MT566456, MT560377 and KJ396328, respectively. The pathogen was identified as F. acuminatum based on morphological and molecular data. Pathogenicity tests were carried out in the greenhouse. Select five healthy Schisandra chinensis seedlings, each with each healthy leaf surfaces inoculated a 1 × 106 spores/mL solution, 3 wells on one side, 10 µL per well. Sterile ddH2O was used in the control experiment. The inoculated seedlings were incubated at 25°C with a relative humidity of 65 to 70% in a greenhouse. Four days after inoculation, all inoculated leaves exhibited the same symptoms as observed in the field, while the controls showed no symptoms. The experiment was repeated three more times with similar results. The re-isolated fungi from the inoculated plants had the same morphology and DNA sequences as the original isolate (ZWWZH) obtained from the field samples, completing Koch's postulates. To our knowledge, this is the first report of F. acuminatum causing leaf spot on Schisandra chinensis in China. F. acuminatum has seriously affected the quality of Schisandra chinensis production. The identification of leaf spot caused by F. acuminatum will enable farmers to identify practices to minimize disease on this important crop.

The potential of novel bacterial isolates from healthy ginseng for the control of ginseng root rot disease (Fusarium oxysporum).

Ginseng root rot caused by Fusarium oxysporum is serious disease that impacts ginseng production. In the present study, 145 strains of bacteria were isolated from the rhizosphere soil of healthy ginseng plants. Three strains with inhibitory activity against Fusarium oxysporum (accession number AF077393) were identified using the dual culture tests and designated as YN-42(L), YN-43(L), and YN-59(L). Morphological, physiological, biochemical, 16S rRNA gene sequencing and phylogenetic analyses were used to identify the strains as Bacillus subtilis [YN-42(L)] (accession number ON545980), Delftia acidovorans [YN-43(L)] (accession number ON545981), and Bacillus polymyxae [YN-59(L)] (accession number ON545982). All three isolates effectively inhibited the growth of Fusarium oxysporum in vitro and the antagonistic mechanism used by the three strains involved the secretion of multiple bioactive metabolites responsible for the hydrolysis of the fungal cell wall. All three biocontrol bacteria produce indoleacetic acid, which has a beneficial effect on plant growth. From our findings, all three antagonistic strains can be excellent candidates for ginseng root rot caused by the pathogenic fungus Fusarium oxysporum. These bacteria have laid the foundation for the biological control of ginseng root rot and for further research on the field control of ginseng pathogens.