IN VITRO FLOWERING OF SPATHIPHYLLUM CANNIFOLIUM: INFLUENCES OF GIBBERELLIC ACID, CULTURE TYPE AND SUCROSE CONCENTRATION

Abstract

In vitro shoots of Spathiphyllum (3-4cm) were cultured for 12 weeks on Murashige and Skoog (MS) media containing different concentrations of GA 3 (0-10 mg/L). Flowering induction was highly related to GA 3 concentrations in the culture media. In solid culture, the first flowering was observed after 56 days of culture and the highest frequency of flowering (83%) was obtained at 10.0 mg/L GA 3 . Plantlets flowered in bioreactor reached 100% flowering after 9 weeks of culture and the inflorescence emergence was advanced by 9 days compare to solid culture. Different sucrose concentrations (0-12%) were used to investigate the role of sucrose as a carbon source. In solid culture, sucrose was indispensable for in vitro flowering. 6% of sucrose was optimal for floral formation while high sucrose levels at 9% and 12% exhibited inhibitory effects. In bioreactor culture, plantlets were able to flower in the absence of sucrose. The first flowering was observed after 42 days of culture in bioreactor at 6% of sucrose. The activities of photosynthetic enzymes during transition to reproductive phase were investigated. Rubisco activity declined after floral induction while PEPcase was highly active. The change in sugar content in the leaves was quantified using HPLC. Sucrose accumulation in the leaves significantly affected inflorescence size and timing of flower induction.