Fragrance and color production from corona and perianth of Iranian narcissus (Narcissus tazetta L.)

Flower color, shape, and scent play crucial roles in attracting pollinators and consumers within the floriculture industry. This study aimed to evaluate the color, scent, and the interactions of eleven Iranian narcissus accessions separately in the corona and perianth tissues, providing insights into the biophysiological differences among these tissues and genotypes. Eleven narcissus genotypes from diverse geographical regions of Iran were collected and cultivated in a greenhouse. Volatile organic compounds (VOCs) were analysed using headspace gas chromatography–mass spectrometry (GCMS). Additionally, the total carotenoid content, color values, tissue thickness, and epidermal cell characteristics were assessed in both the perianth and corona tissues. Scent intensity was evaluated through sensory analysis, and the expression of genes associated with scent and color biosynthesis pathways was examined in both tissues. E-β-ocimene emerged as the dominant volatile organic compound in both the perianth and corona tissues of all the genotypes, with benzyl acetate ranking as the second most abundant VOC in the corona. Both the perianth and corona demonstrated the capacity to produce all types of emitted VOCs detected in a complete flower, although the relative percentage of VOCs varied. However, the specific biological roles of narcissus VOCs in pollinator attraction and plant defence remain unclear. Among the studied genotypes, the corona exhibited a higher carotenoid content. Furthermore, a significant negative correlation was observed between the total carotenoid content and E-β-ocimene content, along with significant positive correlations between 1-deoxy-D-xylulose 5-phosphate reductoisomerase (DXR) and ocimene synthase, and between DXR and the relative gene expression of phytoene synthase (PSY). These findings suggest a shared biosynthesis pathway for carotenoids and monoterpenes, indicating potential competition for the biosynthesis of these compounds.