Ginger (Zingiber officinale Rosc.) is an herbal crop widely grown in China for its medicinal and savory qualities of rhizomes. In August 2018, leaf spot symptoms were observed on ginger plants grown in a field in Nanning, Guangxi Province (E108°3'54", N23°14'48"). Disease incidence was above 50%, and in a Nanning field, rhizome yield loss was almost 30%. Early symptoms appeared as circular, necrotic areas that later developed into circular or irregular spots. The centers of the lesions were white and often surrounded by chlorotic halos (Figure S1A). In severe infections, the spots frequently coalesced, causing the entire leaf to become withered and curved. Small pieces (3 to 4 mm2) from the margin of infected lesions were surface sterilized in 75% ethanol for 40 s followed by 1% NaOCl for 90 s, placed on potato dextrose agar (PDA) and incubated at 28°C in the dark for 4 days. Hyphal tips from the leading edge of colonies were transferred to fresh PDA plates to obtain pure cultures. Fungal colonies were initially white, then turned black/grayish brown when maintained in the dark at 28°C after 5 days (Figure S1B). Conidia were single-celled, brown, or black, smooth, spherical, or subspherical with diameters varying from 9.5 to 15 μm (mean = 13.5 ± 0.72 µm, n = 50) (Figure S1C). Based on these morphological characteristics, the isolates were provisionally identified as Nigrospora oryzae (Ellis 1971; Hudson 1963). Genomic DNA was extracted from a representative isolate Sjb-2. The internal transcribed spacer (ITS) region, beta-tubulin (TUB2), and the translation elongation factor 1-alpha (TEF1-α) were amplified using primer pairs including ITS1/ITS4 (White et al. 1990), Bt-2a/Bt-2b (Glass and Donaldson 1995), and EF1-728F/EF1-986R (Carbone et al. 1999), respectively. The obtained ITS sequence (GenBank accession no. MW555242), TUB2 sequence (MZ048644), and TEF1-α sequence (MZ048645) showed >99% similarity with several GenBank sequences of N. oryzae (KF516962 for ITS; MK550707 for TUB2; and KY019425 for TEF1-α, respectively). Based on the combined sequences of ITS, TUB2 and TEF1-α sequences, a phylogenetic tree was constructed using the maximum likelihood method and confirmed that the isolates were N. oryzae (Figure S2). Pathogenicity of the isolate was confirmed by fulfilling Koch's postulates. Agar blocks (3 mm diameter) containing a fungal mycelium were placed on detached healthy leaves of ginger. The leaves were then wrapped with sterile polyethylene and incubated in a greenhouse at 25°C with 60% RH. Within 7 days, symptoms appeared on inoculated leaves similar to spots observed in the field, whereas controls remained symptomless. The same pathogen was reisolated from the spots. Pathogenicity tests were performed twice with three replications, indicating that N. oryzae is responsible for leaf spot disease on ginger. The disease in ginger caused by N. oryzae had been reported in Southern Africa (Grech et al. 1989). To our knowledge, this is the first report of N. oryzae causing leaf spot of ginger in China. In the field, this pathogen can substantially affect ginger's health and rhizome yield if no effective control measures are implemented. Therefore, management of the disease should be further investigated to avoid major economic losses.

Plant growth-promoting rhizobacteria (PGPR) offer a sustainable alternative to chemical fertilizers in rice production, yet the mechanisms underlying multifunctional growth promotion by individual strains remain insufficiently characterized. In this study, strain ST2023006 was isolated from sugarcane rhizosphere and systematically characterized through phenotypic assays and whole-genome sequencing. The strain was identified as Pseudomonas chlororaphis based on morphological, physiological, biochemical, and multilocus sequence analyses. It exhibited tolerance to temperature (25-37 ℃), pH (5.0-9.0), and salinity (≤2% NaCl). ¹⁵N isotope dilution analysis revealed nitrogen fixation contribution rates of 13.4% and 9.72% to rice roots and shoots, respectively. Pot experiments demonstrated that inoculation significantly promoted growth in two rice varieties, increasing plant height by up to 86.6%, while enhancing root surface area, root volume, and biomass accumulation. In vitro antagonism against Rhizoctonia solani and quantitative IAA analysis (59.44 µg·mL⁻¹) provided experimental support for genome-predicted biocontrol and IAA production traits. Whole-genome sequencing revealed genes potentially associated with nitrogen fixation (nifU, fixI), nutrient mobilization (potassium/zinc solubilization, siderophores), phytohormone synthesis (IAA), stress tolerance (heavy metal resistance, heat/cold shock proteins), and complete biosynthetic gene clusters for the antifungal compounds pyrrolnitrin, phenazine, and hydrogen cyanide. These findings indicate that P. chlororaphis ST2023006 is a promising multifunctional PGPR candidate with demonstrated plant growth-promoting effects and experimentally supported genomic potential for biocontrol.