Biogenic iron oxide nanoparticles (Fe2O3 NPs) adeptly diminish leaf blight of Rosa chinensis by exhibiting higher expression of RcWRKY29 and increasing antioxidant enzymatic activities

Abstract

Rose (Rosa chinensis) is subjected to various biotic and abiotic stresses. In this study, rose leaves with blight symptoms were collected and based on microscopic, morphological, and genetic analyses, the disease-causing pathogen was identified as Aspergillus niger. To our knowledge, this is the first report of leaf blight of R. chinensis in Pakistan. To control this disease, iron oxide nanoparticles (Fe2O3 NPs) were synthesized in the seed extract of Trachyspermum ammi. Suitable formation of synthesized Fe2O3 NPs was tested using reliable techniques. Fourier transformed infrared (FTIR) spectrum of Fe2O3 NPs determined the presence of reducing agent like alcohol, alkyl halide and amine on the surface of NPs. X-Ray diffraction (XRD) analysis depicted crystal-like nature and size (41 nm) of NPs, while scanning electron microscopy (SEM) depicted their spherical shape. Sharp Fe and O peaks were observed by energy dispersive X-ray (EDX) analysis. All concentrations of Fe2O3 NPs (0.25, 0.5, 0.75, 1 and 1.5 mg/ mL) inhibited mycelial growth, in vitro and the greatest inhibition (88.9 %) was observed at 1.0 mg/ mL concentration. SEM micrographs showed severe shrinking and structural decomposition of mycelia at this concentration. In pot experiment, Fe2O3 NPs adeptly controlled blight disease of rose leaves by improving various physiological and biochemical attributes and superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) activities. Findings of Real-Time Quantitative Reverse Transcription PCR (qRT-PCR) showed the higher expression of RcWRKY29 by the application of Fe2O3 NPs, depicting its probable role in plant defense mechanism. These results proved that the application of Fe2O3 NPs can efficiently prevent the spread of blight disease.