Comparative Analysis of Morphological, Histological, and Metabolic Differences of In Vitro- and Ex Vitro-Grown Panax ginseng

Ginseng (Panax ginseng) is highly sensitive to heat stress caused by climate change; thus, the introduction of heat-tolerant cultivars is essential. However, the stable dissemination of heat-tolerant cultivars remains limited due to low propagation efficiency. Plant tissue culture has been introduced as an alternative approach, yet in vitro-grown ginseng often exhibit low survival rates during acclimatization, thereby restricting their practical application. This study was conducted as a fundamental investigation to address this limitation by comparing the morphological, histological, physiological, and metabolic differences between ginseng plants grown in vitro and ex vitro. The results demonstrated that in vitro-grown ginseng had stems and roots that were approximately 30% shorter, less prominent taproot development, and more than 30% lower root fresh weight. These plants also contained about 50% lower chlorophyll content and 52% higher stomatal density compared with ex vitro-grown ginseng. Histologically, in vitro plants exhibited narrow intercellular spaces, underdeveloped root cambium, and lignin deposition in cell walls. Metabolically, in vitro-grown ginseng was clearly distinguishable based on ginsenoside content and volatile compound profiles. The comprehensive findings of this study provide baseline information for future research and can be utilized to enhance the practicality of tissue culture-based micropropagation of ginseng.