Organogenesis of Cucumis metuliferus plantlets under the effects of LEDs and silver nanoparticles

Abstract

Kiwano (Cucumis metuliferus E. Mey. Ex Naudin) is a plant that possesses good medicinal and nutritional values while also being resistant to several important diseases. In vitro propagation of the plant was relatively understudied but holds much potential for mass production requirements. This study was aimed at establishing a protocol for in vitro multiplication of kiwano plants using meta-topolin, silver nanoparticles (AgNPs), and light-emitting diodes (LEDs) treatments. Nodal segments derived from in vitro germinated plantlets were regenerated in MS media supplemented with silver nanoparticles under the illumination of white, red, blue, and red:blue LEDs. A maximum shoot height of 4.66 ± 2.89cm was achieved when 0ppm of AgNPs was added. The highest rooting percentage was obtained at 76.67% with 2.07 ± 1.88 roots per explant using 2ppm AgNP. Silver nanoparticles did not show a positive effect on the in vitro shooting but may have improved rooting of Cucumis metuliferus explants. Red:blue (600-700nm:400-500nm) light produced similar effects as white (400nm-750nm) light in influencing the growth of explants. The absence of red (600-700nm) or blue (400-500nm) lights caused discoloration and shoot tip necrosis in plantlets. Acclimatization was successful with 83% of explants surviving and growing into normal plants using a gradual process with liquid fertilizer. Our findings suggest that meta-topolin is a suitable cytokinin for the growth of in vitro Cucumis metuliferus cultures. White light from 400nm to 750nm contributes optimum growth rate of Cucumis metuliferus explants compared to monochromatic red (600-700nm), blue (400-500nm), or red:blue (600-700nm:400-500nm) lights.