Stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is one of the most devastating diseases of wheat. Resistant cultivars are the preferred strategy to control the disease. Space-induced wheat mutant R39 has adult-plant resistance (APR) to Pst. Genetic analysis indicated that a single recessive gene, designated YrR39, was responsible for the APR of R39 to Pst. Bulked segregant analysis (BSA) combined with a SLAF sequencing (SLAF-seq) strategy was used to fine-map YrR39 to a 17.39 Mb segment on chromosome 4B. The region was confirmed by analysis with simple sequence repeat (SSR) markers. A total of 126 genes were annotated in the region and 21 genes with annotations associated with disease response were selected for further qRT-PCR analysis. The candidate gene Traes_4BS_C868349E1 (annotated as an F-box/LRR-repeat protein) was up-regulated after 12, 24, 48, and 96 hours post inoculation with Pst, suggesting it is likely involved in the resistance. The current study demonstrated that BSA combined with SLAF-seq for SNP discovery is an efficient approach for mapping and identifying candidate functional gene.

Backgrounds: C2H2-type zinc finger protein (ZFPs) form a relatively large family of transcriptional regulators in plants, and play many roles in plant growth, development, and stress response. However, the comprehensive analysis of C2H2 ZFPs in cucumber (CsZFPs) and their regulation function in cucumber are still lacking. Results: In the current study, the whole genome identification and characterization of CsZFPs, including the gene structure, genome localization, phylogenetic relationship, and gene expression were performed. Functional analysis of 4 selected genes by transient transformation were also conducted. A total of 129 full-length CsZFPs were identified, which could be classified into four groups according to the phylogenetic analysis. The 129 CsZFPs unequally distributed on 7 chromosomes. Promoter cis-element analysis showed that the CsZFPs might involve in the regulation of phytohormone and/or abiotic stress response, and 93 CsZFPs were predicted to be targeted by one to 20 miRNAs. Moreover, the subcellular localization analysis indicated that 10 tested CsZFPs located in the nucleus and the transcriptome profiling analysis of CsZFPs demonstrated that these genes are involved in root and floral development, pollination and fruit spine. Furthermore, the transient overexpression of Csa1G085390 and Csa7G071440 into Nicotiana benthamiana plants revealed that they could decrease and induce leave necrosis in response to pathogen attack, respectively, and they could enhance salt and drought stresses through the initial induction of H₂O₂. In addition, Csa4G642460 and Csa6G303740 could induce cell death after 5 days transformation. Conclusions: The identification and function analysis of CsZFPs demonstrated that some key individual CsZFPs might play essential roles in response to biotic and abiotic stresses. These results could lay the foundation for understanding the role of CsZFPs in cucumber development for future genetic engineering studies.

Silica nanoparticles (SiNPs) offer an ecofriendly and environmentally safe alternative for plant disease management. However, the mechanisms of SiNPs-induced disease resistance are largely unknown. This research evaluated the application of SiNPs in controlling the postharvest decay of ginger rhizomes inoculated with Fusarium solani. In vitro study showed that SiNP had little inhibitory effect on mycelial growth and spore germination of F. solani and did not significantly change mycelium’s MDA content and SDH activity. In vivo analysis indicated that SiNPs decreased the degree of decay around the wounds and decreased the accumulation of H₂O₂ after long-term pathogenic infection through potentiating the activities of antioxidant enzymes such as SOD, APX, PPO, and CAT. SiNP150 increased the CHI, PAL, and GLU activity at the onset of the experiment. Moreover, SiNP150 treatment increased total phenolics contents by 1.3, 1.5, and 1.2-times after 3, 5, and 7 days of treatment, and increased total flavonoids content throughout the experiment by 9.3%, 62.4%, 26.9%, 12.8%, and 60.8%, respectively. Furthermore, the expression of selected phenylpropanoid pathway-related genes was generally enhanced by SiNPs when subjected to F. solani inoculation. Together, SiNPs can effectively reduce the fungal disease of ginger rhizome through both physical and biochemical defense mechanisms.

Fusarium solani is one of the most ruinous soil-borne pathogens and seriously affects crop yields and quality worldwide. Ginger is an important medicinal crop, and ginger rhizome extract (GRE) has been used as an alternative for chemical fungicides and bactericides. We investigated the fungistatic effect of GRE on F. solani and analyzed the chemical constituents of GRE using UPLC-MS/MS. Antifungal assay results showed that 20 mg/mL of GRE completely inhibited the growth of F. solani. Morphological analysis revealed that GRE destroyed the morphology and structure of mycelia, thus inhibiting mycelial growth. Furthermore, GRE suppressed the activities of cell wall-degrading and cellular respiratory-related enzymes and decreased the content of fusaric acid, which reduced or even abrogated the infection ability of F. solani. UPLC-MS/MS analysis showed that GRE constituents belonged to eight categories, among which phenolic acids were the highest in content (46.29%) and tannins were the lowest in content (0.06%). When the antifungal activities of major phenolic and flavonoid compounds were evaluated, 4.0 mg/mL 4-hydroxybenzaldehyde and 15.0 mg/mL quercetin were found to completely inhibit F. solani growth. These results highlight GRE as an excellent source of antifungal compounds and suggest the possibility of using 4-hydroxybenzaldehyde and quercetin as natural fungicides to control crop diseases.

Postharvest deterioration of ginger rhizome caused by microorganisms or wound infections causes significant economic losses. Fusarium solani is one of the important causal agents of prevalent ginger disease soft rot across the world. The massive and continuous use of chemical fungicides in postharvest preservation pose risks to human health and produce environmental contamination. Hence, new alternative tools are required to reduce postharvest deterioration and extend the postharvest life of ginger. In this study, the use of silicon nanoparticles (SiNPs) on the storability of ginger rhizomes during postharvest storage and their resistance to Fusarium solani was investigated. The results showed that 50, 100, and 150 mg L⁻¹ of SiNPs increased the firmness of the ginger rhizome during storage but decreased the decay severity, water loss, total color difference, and the reactive oxygen species (ROS; H₂O₂ and superoxide anion) accumulation. Specifically, 100 mg L⁻¹ (SiNP100) demonstrated the best effect in the extension of postharvest life and improved the quality of the ginger rhizomes. SiNP100 application increased the activities of antioxidant enzymes (SOD and CAT) and the total phenolics and flavonoid contents, thereby reducing the ROS accumulation and malondialdehyde (MDA) content. Meanwhile, SiNP100 treatment negatively impacts the peroxidase (POD) and polyphenol oxidase (PPO) activities, which may have contributed to the lower level of lignin and decreased total color difference. SiNP100 likely decreased water loss and the transfer of water by altering the expression of aquaporin genes. Moreover, SiNP100 modulated the expression of lignin synthesis and phytopathogenic responses genes including MYB and LysM genes. Furthermore, SiNP100 inhibited Fusarium solani by preventing the penetration of hyphae into cells, thus decreasing the severity of postharvest pathogenic decay. In summary, this study revealed the physiology and molecular mechanisms of SiNPs-induced tolerance to postharvest deterioration and resistance to disease, which provides a foundation for using SiNPs resources as a promising alternative tool to maintain ginger quality and control postharvest diseases.