Differential modes of disease suppression elicited by silver nanoparticles alone and augmented with Calothrix elenkinii against leaf blight in tomato
2020
Mahawar, Himanshu | Prasanna, Radha | Gogoi, Robin | Singh, Awani Kumar
An investigation employing a detached leaf assay was performed to evaluate the biocontrol efficacy of silver nanoparticles (AgNPs) augmented Calothrix elenkinii against Alternaria alternata infection in tomato. A dose of 50 mg l⁻ ¹ AgNPs was selected, which was based on chlorophyll accumulation (as an index of C. elenkinii growth), microscopic observations and biocidal potential of AgNPs against A. alternata. Higher leaf chlorophyll accumulation and lower endoglucanase activity were recorded in in the AgNPs, C. elenkinii and AgNPs augmented C. elenkinii-treated leaves, compared to pathogen challenge alone. Further, microscopic examination showed that these treatments had an alleviating role towards the damaging effects of A. alternata infection on chloroplasts and leaf structure. PCR based amplification using Internal Transcribed Spacers (ITS)-specific primers revealed no band in the treated samples, illustrating the absence of A. alternata, and the biocontrol efficacy of the treatments. Application of AgNPs, C. elenkinii and AgNPs augmented C. elenkinii imparted a protective effect against A. alternata, by inhibiting the growth of the pathogen in tomato leaves and modulating the growth and enzymatic activities of the host. This method proved valuable for gaining insights into the interplay between cyanobacterium, nanoparticle and pathogen-challenged leaves, and illustrated that AgNPs augmented C. elenkinii has the potential to be scaled up as an effective biocontrol option.
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