Increased emergence of drug resistance and DON pollution pose a severe problem in Fusarium head blight (FHB) control. While the H⁺ antiporter (DHA) family plays crucial roles in drug resistance, the characterization of DHA transporters has not been systematically studied in pathogenetic fungi. In this study, a systematic gene deletion analysis of all putative DHA transporter genes was carried out in Fusarium graminearum, and one DHA1 transporter FgQdr2 was found to be involved in multiple drug resistance, ion homeostasis, and virulence. Further exploration showed that FgQdr2 is mainly localized in the cell membrane; its expression under normal growth conditions is comparatively low, but sufficient for the regulation of drug efflux. Additionally, investigation of its physiological substrates demonstrated that FgQdr2 is essential for the transport of K⁺, Na⁺, Cu²⁺, and the regulation of the membrane proton gradient. For its roles in the FHB disease cycle, FgQdr2 is associated with fungal infection via regulating the biosynthesis of virulence factor deoxynivalenol (DON), the scavenging of the phytoalexin, as well as both asexual and sexual reproduction in F. graminearum. Overall, the results of this study reveal the crucial roles of FgQdr2 in multiple drug resistance, ion homeostasis, and pathogenicity, which advance the understanding of the DHA transporters in pathogenetic fungi.

In September 2014, a root rot and vine decline was observed on melon (Cucumis melo L.) growing in several greenhouses with 85% disease incidence in Zhejiang Province in eastern mainland China. This pathogen had been previously separated from melon in a small area test field in Gansu Province in mainland China (He and Bai 2010). The diseased melons exhibited chlorosis of crown leaves and collapse of vines just prior to harvest. The roots of affected plants exhibited necrotic lesions and loss of secondary and tertiary roots. Brown discolorations of vascular tissues was apparent but rarely extended more than a few centimeters in above-ground plant parts. Numerous perithecia in the root cortex were visible to the naked eye several days after plant death. Small pieces of symptomatic roots were surface sterilized for 1 min with 1% sodium hypochlorite, rinsed in sterile water, and then placed on potato dextrose agar (PDA) medium amended with streptomycin sulphate (25 mg/l). A pale brown colony with white aerial mycelia developed after incubation at 25°C in the dark for 7 days. Black, spherical perithecia, 400 μm in diameter, were present 20 days after incubation on PDA. Each ascus contained a single spherical ascospore, 26-30 μm in diameter, typical of Monosporascus cannonballus Pollack & Uecker (Pollack and Uecker 1974). DNA from this isolate was extracted and the internal transcribed spacer (ITS) region was amplified using the primers ITS1 and ITS4 (White et al. 1990), sequenced, and submitted to GenBank (Accession No. KT826570). BLAST indicated that the 564-bp sequence shared 99% identity with M. cannonballus in C. melo (Accession No. AM167937.1). Pathogenicity tests were performed on melon (cv. Yellow 9818) in a temperature-controlled growth chamber. Five 7-day-old mycelial plugs (5 mm in diameter) from colony periphery were inoculated to 100 ml sand-wheat grain medium (3 Vboiled bulge wheat grain: 1 Vsand) and kept at 25°C in the dark for 15 days. The medium overgrown with mycelial was used as inoculum. Five melon seeds were sown in sterilized potting mixture(1 Vsand: 1 Vpeat moss) and inoculum was added to reach a soil concentration of 5%. Five melons grown in noninoculated containers were used as controls. The plants inoculated showed root necrosis and cotyledon wilt after 10 days with an 12-h photoperiod at 30°C/20°C while the controls were symptomless. M. cannonballus was reisolated from symptomatic roots confirming Koch's postulates. This disease has been reported on watermelon and/or melon in 19 countries around the world including Egypt, India, Italy, Japan, Korea, Mexico, Spain, Taiwan and the United States (Cohen et al. 2012; Martyn and Miller 1996). To our knowledge, this is the first report of M. cannonballus on melon in eastern mainland China, extending the known range of the pathogen in China. Due to the wide distribution of melon cultivation and the loose transport policy to plant materials, there is a potential risk for disease spread throughout the country. So grafting of melon onto Cucurbita spp. more tolerance to the pathogen would be an effective disease management. References: Cohen, R., et al. 2012. Hortic. Rev. 39:77-120. He, S. Q., and Bai, B. 2010. Plant Pro. (In Chinese) 36:116-119. Martyn, R. D., and Miller, M. E. 1996. Plant Dis. 80:716-725. Pollack, F. G., and Uecker, F. A. 1974. Mycol. 66:346-349. White, T. J., et al. 1990. Pages 315 in: PCR Protocols: A Guide to Methods and Applications. M. A. Innis et al., eds. Academic Press, San Diego, CA.

Rhizosphere microorganisms play pivotal roles in mitigating the challenges associated with continuous cropping in melon cultivation. While grafting and plant growth-promoting rhizobacteria (PGPR) independently influence rhizosphere microbial communities, their combined effects remain largely unexplored. This study investigates the synergistic regulation of Paenibacillus polymyxa NBmelon-1 inoculation and grafting on rhizosphere microbiome assembly, plant performance, and disease resistance in melon self-rootstocks. Field experiments demonstrated that NBmelon-1 inoculation significantly enhanced rootstock stem diameter (95.3% increase in spring) and root development, achieving a graft survival rate exceeding 95%. The combined treatment (NB+GJ) increased scion fruit yield by 29.8% in autumn and 36.5% in spring, as well as the single-fruit weight by 22.5% in autumn and 37.3% in spring, while maintaining fruit morphology. Integrated 16S rRNA and ITS sequencing revealed that the NB+GJ treatment selectively enriched antagonistic bacterial phyla (e.g., Firmicutes and Actinobacteriota) and suppressed pathogenic fungi (e.g., Fusarium and Melanconiella). Seasonal shifts in microbial diversity and functional gene profiles underscored the dynamic interplay between treatments and environmental factors. These findings establish a novel strategy for optimizing melon self-rootstock grafting systems and sustainably managing soil-borne diseases.

In 2022, an outbreak of fungal rot disease affected luffa crops in Shanghai and Zhejiang Province. Infected plants exhibited symptoms including yellowing, chlorosis, wilting, and water-soaked occurred on leaves and fruits. Dark brown, concave lesions developed, often accompanied by white or pale pink mold under moist conditions. Fourteen pathogen strains, morphologically resembling Fusarium species, were isolated. Molecular analysis confirmed Fusarium incarnatum as the causative agent. Pathogenicity tests on luffa plants fulfilled Koch’s postulates, with inoculated plants displaying the same symptoms. Re-isolation of the fungus from the inoculated plants confirmed its role in the disease. To our knowledge, this is the first report of F. incarnatum causing leaf spot and fruit rot on luffa in China. Moreover, the soil bacterial strain Bacillus velezensis BV171 displayed strong inhibition of F. incarnatum mycelia growth and promoted the growth of sponge gourd plants. These findings lay the foundation for the development of diagnostic tools, disease management strategies, and the breeding of resistant luffa varieties.

Maintaining cellular calcium (Ca²⁺) homeostasis is essential for many aspects of cellular life. The high-osmolarity glycerol (HOG) mitogen-activated protein kinase (MAPK) pathway responsible for signal integration and transduction plays crucial roles in environmental adaptation, especially in the response to osmotic stress. Hog1 is activated by transient Ca²⁺ increase in yeast, but the functions of the HOG pathway in Ca²⁺ homeostasis are largely unknown. We found that the HOG pathway was involved in the regulation of Ca²⁺ homeostasis in Fusarium graminearum, a devastating fungal pathogen of cereal crops. The deletion mutants of HOG pathway displayed increased sensitivity to Ca²⁺ and FK506, and elevated intracellular Ca²⁺ content. Ca²⁺ treatment induced the phosphorylation of FgHog1, and the phosphorylated FgHog1 was transported into the nucleus by importin β FgNmd5. Moreover, the increased phosphorylation and nuclear accumulation of FgHog1 upon Ca²⁺ treatment is independent of the calcineurin pathway that is conserved and downstream of the Ca²⁺ signal. Taken together, this study reported the novel function of FgHog1 in the regulation of Ca²⁺ homeostasis in F. graminearum, which advance the understanding of the HOG pathway and the association between the HOG and calcineurin pathways in fungi.

Squash leaf curl China virus (SLCCNV) belongs to the species Begomovirus cucurbitachinaense in the genus Begomovirus and can infect some Cucurbitaceae crops except for watermelon (Citrullus lanatus). In this study, watermelon plants showing symptoms typical to begomovirus infection in field were observed in Zhejiang Province of China, and SLCCNV presence was identified through PCR and next-generation sequencing (NGS). The pairwise sequence identity of the DNA-A genome shows that SLCCNV watermelon isolate belongs to the SLCCNV/CN strain and shares 96% nucleotide identity with the previously sequenced SLCCNV/CN. An infectious clone of SLCCNV watermelon isolate was constructed using the tandem repeat fragment method. Through agrobacterium-mediated inoculation, the clone could induce systemic infection with typical symptoms in watermelon, melon (Cucumis melo), squash (Cucurbita pepo), pumpkin (Cucurbita maxima), wax gourd (Benicasa hispida), cucumber (Cucumis sativus), and N. benthamiana. It was further demonstrated that the progeny virions derived from the cloned watermelon isolate could be transmitted by whitefly rather than the sap. To the best of our knowledge, this is the first report of a natural infection of SLCCNV on watermelon in China, and the first complete report on the molecular characteristics and pathogenicity of watermelon-infecting SLCCNV in the world.