Enhanced Production of Apocarotenoids by Salicylic Acid Elicitation in Cell Suspension Cultures of Saffron (Crocus sativus L.)

A cell suspension culture of saffron (Crocus sativus L.) was previously established fromstyle-derived calli to obtain an in vitro system for crocin, an uncommon and valuable water-solubleapocarotenoid, and carotenoid production suitable for future scaling up. To shed more light on thecorrelation between apocarotenoid biosynthesis and key-gene expression, in this study, SA was usedat 0.5 mM concentration to elicit crocin production and the effects on carotenoid production wereanalyzed after 6, 12, 24, and 48 h. HPLC-DAD analysis was used for total crocin quantification as wellas the other carotenoids zeaxanthin, ?-carotene and lutein. Quantitative RT-PCR was used to analyzethe transcript levels of saffron apocarotenoid biosynthetic key genes PSY (phytoene synthase), BCH1(?-carotene hydroxylase), and CCD2 (carotenoid cleavage dioxygenase) after SA elicitation. In saffronsuspension-cultured cells elicited by SA, the carotenoid biosynthetic pathway was mostly enhancedtoward crocin biosynthesis, known to exert strong biological activity and therapeutic effects, ratherthan lutein or xanthins. SA increased BCH1 and CCD2 gene expression 15.6 and 3.3 times, respectively,compared to the control at 24 h after elicitation. Although a dynamic change of metabolite contentsand gene expression was observed during the 48 h time course in response to SA elicitation, thechanges of zeaxanthin and crocin were consistent with the regulation of the corresponding genes BCHand CCD2 during the time course. In conclusion, the effects of SA on regulation of gene expressionin the apocarotenoid pathway could be successfully applied for the biotechnological productionof crocin.