Morpho-Physiological and Biochemical Response of Monk Fruit Plant to Charged Gold Nanoparticles Under In Vitro Conditions

Abstract

Monk fruit (Siraitia grosvenorii) is a dioecious and perennial plant endemic to subtropical China. It has recently gained importance as a low-calorie natural sweetener due to the US Food and Drug Administration and European Food Safety Authority approving it as non-nutritive sweeteners (NNS) for the food and beverage industry. NNS are sweet compounds with little or no energy, which can retain the sweetness of packaged edibles and are safe for human consumption, weight management and cardiometabolic disease prevention. To achieve mass-scale propagation and production of elite planting material, tissue culture technology has been used for the past several years. In the present study, we demonstrate that supplementation of citrate- and cetyltrimethylammonium bromide-coated gold nanoparticles (AuNPs) in Murashige and Skoog medium positively impacts the in vitro development and multiplication of S. grosvenorii. The morpho-physiological and biochemical parameters of S. grosvenorii were found to be differentially regulated along the concentration gradients (10–100 µM) of citrate- and CTAB-coated AuNPs supplemented in MS medium. We observed that the morphological, physiological and biochemical parameters were maximum in S. grosvenorii proliferated on MS medium supplemented with 40-µM CTAB-coated AuNPs but minimum in S. grosvenorii propagated on MS medium containing 100-µM citrate-coated AuNPs. Moreover, auxin and jasmonic acid signalling-related genes (YUC9 and ARF8) were overexpressed in 40 µM CTAB-coated AuNPs plants, while their expression was reduced in 100 µM citrate-coated AuNPs plants. These findings provide an efficient protocol for AuNP-mediated elicitation of in vitro mass-scale monk fruit propagation.