Transgenic Research - Pathogenic fungi represent one of the major biotic stresses for soybean production across the world. Sclerotinia sclerotiorum, the causal agent of Sclerotinia stem rot, is a... 相似文献
Sclerotinia stem rot (SSR), caused by the oxalate-secreting necrotrophic fungal pathogen Sclerotinia sclerotiorum, is one of the devastating diseases that causes significant yield loss in soybean (Glycine max). Until now, effective control of the pathogen is greatly limited by a lack of strong resistance in available commercial soybean cultivars. In this study, transgenic soybean plants overexpressing an oxalic acid (OA)-degrading oxalate oxidase gene OXO from wheat were generated and evaluated for their resistance to S. sclerotiorum. Integration and expression of the transgene were confirmed by Southern and western blot analyses. As compared with non-transformed (NT) control plants, the transgenic lines with increased oxalate oxidase activity displayed significantly reduced lesion sizes, i.e., by 58.71–82.73% reduction of lesion length in a detached stem assay (T3 and T4 generations) and 76.67–82.0% reduction of lesion area in a detached leaf assay (T4 generation). The transgenic plants also showed increased tolerance to the externally applied OA (60 mM) relative to the NT controls. Consecutive resistance evaluation further confirmed an enhanced and stable resistance to S. sclerotiorum in the T3 and T4 transgenic lines. Similarly, decreased OA content and increased hydrogen peroxide (H2O2) levels were also observed in the transgenic leaves after S. sclerotiorum inoculation. Quantitative real-time polymerase chain reaction analysis revealed that the expression level of OXO reached a peak at 1 h and 4 h after inoculation with S. sclerotiorum. In parallel, a significant up-regulation of the hypersensitive response-related genes GmNPR1-1, GmNPR1-2, GmSGT1, and GmRAR occurred, eventually induced by increased release of H2O2 at the infection sites. Interestingly, other defense-related genes such as salicylic acid-dependent genes (GmPR1, GmPR2, GmPR3, GmPR5, GmPR12 and GmPAL), and ethylene/jasmonic acid-dependent genes (GmAOS, GmPPO) also exhibited higher expression levels in the transgenic plants than in the NT controls. Our results demonstrated that overexpression of OXO enhances SSR resistance by degrading OA secreted by S. sclerotiorum and increasing H2O2 levels, and eliciting defense responses mediated by multiple signaling pathways.
Semi-interpenetrating polymer network (semi-IPN) hydrogels were prepared by UV irradiation of water-soluble N-carboxylethyl chitosan (CECS) and 2-hydroxyethyl methacrylate (HEMA) aqueous solutions in the presence of D-2959 as photoinitiator. Hydrogels were characterized by using scanning electron microscopy (SEM), thermal gravimetric analysis (TGA) and X-ray diffractometry (XRD). SEM showed that semi-IPN hydrogels displayed porous surface and therefore had high surface area. XRD indicated that CECS/poly (HEMA) semi-IPN hydrogels had amorphous structure. The thermal stability and equilibrium degree of swelling improved obviously with increase of CECS content. Differential scanning calorimetry (DSC) indicated that free water content increased with increase of CECS content while bonded water content decreased. Cytotoxicity results suggested that semi-IPN hydrogels had good biocompatibility. From these preliminary evaluations, it is possible to conclude that these materials have potential applications in the biomedical field. 相似文献
A novel glycogen synthase kinase-3 gene, GmGSK, was isolated from Glycinemax. It is 1,596 bp in length with one ORF of 410 amino acids. Southern blot analysis revealed that it has at least two copies
in the G. max genome. GmGSK, when transiently expressed in Nicotiana tabacum leaves, was localized in both cell membrane and cytoplasm. Northern blot analysis indicated that GmGSK is expressed in all tissues, with highest expression in the root. GmGSK can be induced by various abiotic stresses. When transformed with GmGSK, Saccharomyces cerevisiae exhibited enhanced resistance to salt and drought stress. 相似文献