For fast and easy isolation of inhibitor-free genomic DNA even from the toughest plant leaf samples, including those high in polyphenols and polysaccharides, a protocol has been developed. To prevent the solubility of polysaccharides in the DNA extract, high salt concentration (1.4 M) was used in the extraction buffer. Polyvinylpyrrolidone (PVP) was used for the removal of polyphenols as polymerase chain reaction (PCR) inhibitors. Proteins like various enzymes were degraded by proteinase K and removed by centrifugation from plant extracts during the isolation process resulting in pure DNA and RNA ready to use in downstream applications including PCR, quantitative polymerase chain reaction (qPCR), ligation, restriction and sequencing. This protocol yielded a high molecular weight DNA and RNA isolated from leaves and roots of recalcitrant plants which was free from contamination and color. The average yields of total RNA from roots and shoot of Betula and Grape ranged from 285 to 364 ng/µl with A260/A280 between 1.9 and 2.08. The RNA isolated with this protocol was verified to be suitable for PCR, quantitative real-time PCR, semi-quantitative reverse transcription polymerase chain reaction, cDNA synthesis and expression analysis. This protocol shown here is reproducible and can be used for a broad spectrum of plant species which have polyphenols and polysaccharide compounds.

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COVID-19 is one of the viral diseases that has caused many deaths and financial losses to humans. Using the available information, this virus appears to activate the host cell-death mechanism through Calpain activation. Calpain inhibition can stop its downstream cascade reactions that cause cell death. Given the main roles of Calpain in the entry and pathogenicity of the SARS-CoV-2, its inhibition can be effective in controlling the COVID-19. This review describes how the virus activates Calpain by altering calcium flow. When Calpain was activated, the virus can enter the target cell. Subsequently, many complications of the disease, such as inflammation, cytokine storm and pulmonary fibrosis, are caused by virus-activated Calpain function. Calpain inhibitors appear to be a potential drug to control the disease and prevent death from COVID-19.