Tissue culture is a promising technique to produce a large number of true to type plants in coffee.  One of the major obstacles encountered in in-vitro propagation is the high percentage of contamination of explants which is mainly observed when field grown plants are used as the source of explants. Several research studies were carried out to reduce the percentage of microbial contamination either using disinfectants during explant preparation or antifungal and anti-bacterial chemicals in media. The present paper elucidates the effect of ZnO Nanoparticles (ZnO-NPs) in reducing contamination and enhancing recovery of in vitro cultured leaf explants of arabica coffee (Coffea arabica). MS media containing ZnO-NP at three different concentrations were tested in an improved hybrid line of Coffea arabica (S.4595). Among the various concentrations tested, media containing 25mg/L of ZnO-NPs showed maximum recovery of explants. ZnO-NPs also positively influenced the induction of callus and somatic embryos which was significantly higher than the control.

Although various antifungal and antibacterial chemicals are available for use in in vitro cultures, they were often detrimental to the growth and differentiation of cultured explants. In recent years various studies have proved the antimicrobial properties of nanoparticles. Nanoparticles have been used for surface disinfection and recovery of explants in tissue culture experiments of potato, barley, valerian, grape vine, olive, tobacco and banana. Among various nanoparticles, ZnO-NPs, in particular are found to improve callus growth and plant regeneration and in the production of contamination free cultures in Banana . The antibacterial property of ZnO-NP was also proved in the studies of Pal et al., 2017 and Aquisman et al., 2020 wherein ZnO-NP was synthesized using plant extracts and tested for its anti-microbial properties.

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Regards,
Alex Stewart
Journal Coordinator