Aug 2026· Current Issues in Molecular Biology· Vol 48, pp. 858· 0 citations· 44 references
TL;DR
The AhDef1 gene functionally validated in this study emerges as a promising candidate for engineering fungal disease resistance and aflatoxin mitigation in peanut and potentially other susceptible crops.
Abstract
The aim of the present study is functional characterization of a native plant defensin gene (AhDef1) from Arachis hypogaea (peanut). Further its potential has been evaluated to enhance resistance against Aspergillus flavus infection and reduce aflatoxin accumulation through transgenic intervention. Transgenic peanut lines overexpressing the AhDef1 gene exhibited significantly improved resistance to A. flavus colonization and a marked reduction in aflatoxin B1 content compared to wild-type (WT) plants. Quantitative real-time PCR confirmed transgene expression, and aflatoxin accumulation was analyzed by a spectrophotometer which revealed a reduction in aflatoxin levels in the transgenic seeds. Alongside its direct antifungal activity, AhDef1 overexpression also triggered the upregulation of genes which are involved in the biosynthesis of secondary metabolites such as resveratrol, ferulic acid and butenedioic acid, myoinositol, octadecanoic acid, suggesting an amplified biochemical defense response. Multivariate analysis further suggested that accumulation of these defense-related metabolites was positively correlated with transgenic lines challenged by A. flavus. In conclusion, the AhDef1 gene functionally validated in this study emerges as a promising candidate for engineering fungal disease resistance and aflatoxin mitigation in peanut and potentially other susceptible crops.
BACKGROUND
Peanut (Arachis hypogaea L.) is an important oilseed crop whose yield is threatened by various abiotic stresses. Glycosyltransferases are crucial for diverse plant functions, including the regulation of plant growth and development, biotic and abiotic stress response, and the biosynthesis of secondary metabolites. However, the mechanism of glycosyltransferases relates to abiotic stresses remains unclear in peanut.
RESULTS
In this study, we isolated a novel gene, AhIRX7, from a salt-tolerant mutant of peanut. The expression of AhIRX7 was strongly induced by NaCl and PEG6000. Overexpression of AhIRX7 led to increased, whereas silenced of AhIRX7 resulted in decreased tolerance of peanut seedlings to salt and drought stresses. Compared to wild-type (WT), the overexpression lines showed significantly increased chlorophyll fluorescence parameters and reduced photodamage under salt and drought stress. Their activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) were markedly enhanced, while the accumulation of superoxide anion (O2-), hydrogen peroxide (H2O2) and malondialdehyde (MDA) were significantly reduced. In contrast, AhIRX7-silenced lines exhibited opposite trends in SOD, POD, and CAT activities, as well as MDA accumulation. Consequently, overexpression of AhIRX7 improved the regulation of photosynthesis, the dynamics of stomatal opening and closing under salt and drought stress in Arabidopsis plants.
CONCLUSIONS
Overall, this study indicated that AhIRX7 gene functions in enhancing drought and salt stresses in peanuts and Arabidopsis, which may serve as a candidate gene for use in improving abiotic stress resistance in crops.
Yanyan Tang, Xiaoting Li, Wenlin Wang et al.· BMC Plant Biology· 0 citations
Strawberry (Fragaria × ananassa) is highly susceptible to gray mold caused by Botrytis cinerea. WRKY transcription factors and jasmonic acid (JA) are central to defense against necrotrophs, yet the regulatory interaction in strawberry remains unclear. Here, we characterized FaWRKY21, a terpinen-4-ol-responsive, Group IIc WRKY gene encoding a nuclear-localized protein. Transient overexpression in strawberry fruit enhanced defense against B. cinerea and increased endogenous JA concentrations. This enhanced defense was confirmed in transgenic Arabidopsis plants overexpressing FaWRKY21, where AtPDF1.2 and other defense markers were upregulated. Transcriptomic and qRT-PCR analyses revealed that FaWRKY21 upregulates JA biosynthetic genes, notably FaOPR3II, FaJMT, and FaAOS-C. Yeast one-hybrid, EMSA, and dual-luciferase assays demonstrated direct binding to W-box elements in their promoters and transcriptional activation. Our findings establish FaWRKY21 as a direct activator of JA biosynthesis that positively regulates defense against B. cinerea, offering molecular targets for developing elicitor-based strategies to control postharvest gray mold.
Meng-Ze Wei, Yi Chen, Yijia You et al.· Journal of Agricultural and...· 0 citations
Verticillium dahliae is a devastating soil-borne fungal pathogen that causes severe yield losses in melon (Cucumis melo L.) and other crops. Identifying novel resistance genes is crucial for sustainable disease management. In this study, we characterized the function of CmVQ23, a candidate gene previously identified through QTL mapping, in mediating defense against V. dahliae using heterologous expression in Arabidopsis thaliana. Subcellular localization assays revealed that the CmVQ23-eGFP fusion protein predominantly localized to the nucleus, consistent with its predicted role as a co-factor of transcription factor. Upon V. dahliae inoculation, CmVQ23-overexpressing Arabidopsis lines exhibited significantly reduced disease indices and restricted fungal proliferation compared with wild-type and mutant plants, although these lines displayed altered vegetative growth, including delayed bolting and reduced plant height. Mechanistically, CmVQ23 overexpression promoted reactive oxygen species (ROS) accumulation and hypersensitive response (HR)-mediated cell death at infection sites, as evidenced by intensified DAB and trypan blue staining. Furthermore, transgenic lines maintained higher photosynthetic efficiency, enhanced antioxidant enzyme activities, and increased lignin deposition via upregulation of phenylalanine ammonia-lyase (PAL) and polyphenol oxidase (PPO). Notably, CmVQ23 overexpression markedly upregulated both salicylic acid (SA)- and jasmonic acid/ethylene (JA/ET)-responsive marker genes, including AtPR1, AtPR2, AtPR5, AtPAD4, AtPDF1.2, and AtVSP2 upon infection. Collectively, these findings demonstrate that CmVQ23 functions as a positive regulator of resistance to Verticillium dahliae by orchestrating ROS/HR-mediated cell death, antioxidant defense, phenylpropanoid pathway activation, and phytohormone signaling crosstalk, offering a promising genetic resource for improving Verticillium wilt resistance in crops.
Engineering broad‐spectrum disease resistance remains a major challenge in crop improvement because most resistance genes are effective against a limited range of pathogens. Pathogenesis‐related (PR) proteins, particularly endochitinases, are promising targets for enhancing plant immunity due to their antimicrobial activity and ability to activate defense responses. Here, we generated transgenic tomato (Solanum lycopersicum L.) plants overexpressing an endochitinase gene to assess their potential for enhanced resistance against bacterial and fungal pathogens. Three independent overexpression lines and the wild type were evaluated for transgene expression, chitinase activity, defense‐related gene expression, and resistance after inoculation with Xanthomonas euvesicatoria pv. perforans (Xep) and Sclerotinia sclerotiorum. The transgene was strongly expressed in all transgenic lines, whereas chitinase activity increased by up to fivefold compared with the wild type. Endochitinase overexpression activated defense responses, with marked induction of PR1 expression, reaching a maximum increase of over 480‐fold, and enhanced expression of defense‐associated genes, including SlACS and SlACO. Compared with the wild type, the most responsive transgenic lines showed reductions of up to 79.7% in bacterial spot severity and 85.6% in white mold severity. These findings demonstrate that endochitinase overexpression activates defense signaling and improves broad‐spectrum resistance, representing a promising strategy for developing disease‐resistant tomato cultivars.
Lucas José de Sousa, A. C. Bezerra, Ivonaldo Reis Santos et al.· Biotechnology Journal· 0 citations
Fungal pathogens cause severe yield losses in lettuce production worldwide. We developed transgenic lettuce lines overexpressing the ch5B chitinase gene from Phaseolus vulgaris (bean) under the regulation of the rbcS1 (ribulose-1,5-bisphosphate carboxylase small subunit) promoter. Molecular characterization confirmed stable transgene integration and expression across the selected lines. In vitro assays demonstrated that transgenic leaf extracts significantly inhibited Rhizoctonia solani mycelial growth. Furthermore, inoculation assays in both seedlings and adult plants in the greenhouse showed a significant reduction in lesion areas compared to non-transgenic (NT) controls. Finally, two lines were evaluated in field trials, both showing agronomic substantial equivalence to the NT, satisfying international biosafety frameworks for commercial development. Among them, the ch5B 3-4 line appears to be the most promising candidate for further studies, as it showed slightly higher fresh weight compared to the NT under field conditions.:
Laura M. Radonic, V. Beracochea, C. V. Filippi et al.· Agronomy· 0 citations
Bacterial wilt, caused by the bacterium Ralstonia solanacearum, is a devastating disease that limits peanut production. The molecular mechanisms that distinguish between resistant and susceptible responses are being continuously explored; however, there is limited data with regard to the interaction between lipid metabolism and transcriptional reprogramming. Here we performed integrated sphingolipidomics and transcriptomics on the roots of the resistant peanut variety Zhonghua 6 (ZH6) and the susceptible variety Zhonghua 12 (ZH12) at pre-disease, early-onset, and late stages of infection. The resistant ZH6 variety exhibited the early accumulation of specific glucosylceramides (GluCer t18:1/h25:0 and GluCer t18:0/h23:0) and inositol phosphoceramide (IPC t18:0/h24:0). Metabolic stabilization occurred, with no significant lipid changes observed between the early and late stages. This response was supported by transcriptional activation of fatty acid α-hydroxylase (0538LJ), neutral/alkaline ceramidases (IX12GR, KZ47MP.1), and ABA signaling components (ABA receptor, SRK2A-like). In contrast, susceptible ZH12 displayed progressive sphingosine depletion and delayed accumulation of VLCFA-ceramide d18:0/16:0 and sterols. KCS4 was upregulated in ZH12, providing a transcriptional basis for VLCFA-ceramide accumulation. Hormone signaling divergence was evident: ZH6 exhibited early ABA signaling, followed by transcriptional stasis, whereas ZH12 displayed delayed ACS4/ACS11 hyper-induction after pathological ceramide accumulation. This was accompanied by auxin depletion (GH3.9 upregulation), failure of the cytokinin phosphorelay (HPt6 suppression), and decoupling of SA signaling (PR-1 induction without TGA activation). Resistance is therefore defined by early, coordinated sphingolipid remodeling and ABA signaling leading to homeostatic stabilization. In contrast, susceptibility represents delayed ceramide accumulation and multi-hormone signaling suppression. This multi-omics framework provides detailed lipidomic and transcriptomic signatures to identify candidate genes and lipid biomarkers for marker-assisted breeding of bacterial wilt-resistant peanut varieties.
Yuzhuo Xia, Zhenzhen Zhang, Jian Yang et al.· Agronomy· 0 citations
