Fragrance and color production by corona and perianth tissues of Iranian narcissus genotypes (Narcissus tazetta L.)

Flower color, shape and scent are the most attracting factors for consumers in the floriculture industry. The most fragrant Iranian narcissi (Narcissus tazetta L.) grown in natural habitats are Shahla, Meskinak, and Porpar genotypes. The present study was conducted to evaluate the color, scent, and also their interaction separately in corona and perianth of eleven Iranian narcissus accessions, for a better understanding of the bio-physiological differences in these tissues. For this purpose, the volatile organic compounds (VOCs) were analyzed using Headspace GCMS (gas chromatography/mass spectrometry); and total carotenoid, color values, and tissue thickness were measured in both perianth and corona tissues. Sensory analysis for corona and perianth was also conducted to evaluate scent perception. Besides, the expression of genes related to scent and color in corona and perianth was evaluated. Moreover, epidermal cells of perianth and corona were assessed by polarized light and SEM microscopy. The two most abundant compounds in both tissues were E-{beta}-ocimene and benzyl acetate, respectively; among which the first compound was higher in perianth, while the second one was higher in corona. Among identified VOCs, -terpineol, acetic acid, 2-phenylethyl ester, -pinene, {beta}-myrcene, and limonene were detected in corona of all genotypes of N. tazetta; however, these compounds were not identified in perianth of every genotypes. In corona, the negative correlations between the measured values of E-{beta}-ocimene and carotenoid and also, between the expression level of ocimene synthase and PSY (Phytoene synthase) with DXR (1-Deoxy-D-xylulose 5-phosphate reductoisomerase) suggested that there might be a competition between carotenoids and monoterpenes precursors in the MEP (methyl-D-erythritol phosphate) pathway. Volatile organic compound, color, scent emission, fresh weight and thickness of tissue were different in perianth and corona; while the surface coverage (with epidermal conical cells) were similar in these tissues. The findings of this research illustrated clearly for the first time that while both perianth and corona play important roles in scent production, corona has a more distinguished role in greater production of scent and color in Iranian narcissus flowers.