Abstract

Mulberry (Morus sp.) cultivar ‘Sakon Nakhon’ is an important industrial crop, particularly for the production of high-value secondary metabolites. Strategies to enhance secondary metabolite production under controlled cultivation are gaining increasing attention. This study aimed to investigate the effects of chitosan application on molecular changes in root tissues, together with physiological responses in roots and leaves of aeroponically grown mulberry plants. 2.5-month-old plants grown in an aeroponic system were treated with 0.04% (w/v) chitosan during the final two weeks and compared with plants supplied with a full nutrient (FN) solution. The results showed that chitosan application did not affect plant growth. No significant differences were observed in SPAD Green Index, specific leaf weight (SLW), or specific root length (SRL) between treatments, indicating stable physiological performance. Although no significant physiological differences were detected, transcriptomic analysis of root tissues revealed pronounced molecular changes following chitosan application. Genes associated with secondary metabolite biosynthesis were significantly upregulated, including those encoding trans-resveratrol di-O-methyltransferase, (3S,6E)-nerolidol synthase 1, and (–)-limonene synthase. The upregulation of these genes indicates that chitosan functions as an effective biotic elicitor in aeroponic mulberry production, promoting the biosynthesis of high-value secondary metabolites without adversely affecting plant growth.