Exogenous ACC as an Elicitor of Aromatic Amino Acid Accumulation and Secondary Metabolism in Rice Kernel

The increasing global population coupled with the reduction of arable land underscores the urgent need for nutritionally enhanced crops. Rice (Oryza sativa L.), as a staple food for millions, can benefit from elevated levels of aromatic amino acids such as phenylalanine, which serve as precursors for essential secondary metabolites including flavonoids and anthocyanins. These compounds possess strong antioxidant properties, mitigating oxidative stress and potentially reducing the risk of chronic diseases in consumers, while also enhancing the aroma, taste, and visual quality of rice grains. In this study, foliar application of ۱-aminocyclopropane-۱-carboxylic acid (ACC), a direct ethylene precursor, was employed at concentrations of ۱.۰, ۱.۵, and ۲.۰ g/L (corresponding to approximately ۹.۹, ۱۴.۸, and ۱۹.۸ mM, respectively) to assess its effect on aromatic amino acid biosynthesis in two local Iranian rice cultivars, Helal and Keshvari, during seed formation and filling. Gene expression analyses focused on PAL (phenylalanine ammonia-lyase) and ADT (arogenate dehydratase), key enzymes regulating phenylalanine catabolism and biosynthesis. Results demonstrated cultivar-dependent responses: in Helal, PAL expression was maximally upregulated at ۱.۵ g/L ACC, while ADT expression significantly increased at ۱ g/L. Conversely, Keshvari exhibited the strongest ADT induction at ۲ g/L ACC, with PAL showing moderate changes. These findings highlight the importance of genetic background in modulating the efficacy of ethylene-mediated elicitation. Overall, ACC foliar treatment represents an environmentally friendly approach to enhance aromatic amino acid content and secondary metabolite accumulation in rice, offering potential improvements in nutritional quality, stress resilience, and organoleptic properties

کلیدواژه ها:

Rice Cultivars ، ACC elicitation ، Aromatic amino acids