2018 ASHS Annual Conference

Chinese narcissus (Narcissus tazetta var. chinensis) was introduced 1300-1400 years ago and naturalized in coastal areas and offshore islands of southeastern China. It is one of popular Chinese traditional indoor flowers and famous flowering bulbs in the world with only two white-tepal triploid cultivars, ‘Jinzhan Yintai’ and ‘Yulinglong’. Recently, a yellow tepal mutant was discovered and gained popularity quickly. We conducted pigment metabolite analysis and comparative transcriptome profile for ‘Jinzhan Yintai’ and the mutant. The tepal epidermis of the mutant had much more and larger chromoplasts than those of ‘Jinzhan Yintai’. UV-visible spectroscopy concluded that total flavonoids and carotenoids were semi-quantified in five flowering stages, from green-tepal to semi-perish stage. Although no significant difference between the mutant and ‘Jinzhan Yintai’ when quantitative determination of total flavonoid content, the total carotenoids of the mutant were more than 10-fold higher. Using comparative KEGG pathway enrichment analysis, carotenoid related pathways in the two cultivars showed significant variations. The structure of carotenoids biosynthetic pathway in both cultivars was completed and DXS and GGPS genes expressed even higher in white narcissus. The downstream PSY and NCED genes, which played the essential roles in synthesis and cleavage of carotenoids respectively, were found to express in an opposite way. In white narcissus, the expression of PSY was decreased, while NCED genes in carotenoids degradation sub-pathway was increased. In mutant, though PSY, ZDS, LCY, even NCED were accumulated along with the flower open process, PSY displayed up-regulated expression and NCED down regulated remarkably when compared to the transcriptome of ‘Jinzhan Yintai’. Therefore, adequate color pigments synthesized from carotenoids metabolic pathway in chromoplasts of the mutant tepals were not degraded, which led to the color differentiation.