Study On Polyamines Roles In Somatic Embryogenesis In Asparagus Officinalis L.

The physiological and biochemical changes were studied during somatic embryogenesis in Asparagus (Asparagus officinalis L. cv UC800), and roles of polyamines on somatic embryogenesis and the mechanism were investigated.1. The conditions for somatic embryogenesis in Asparagus were optimized. The most suitable medium were: MS+NAA 1mg ·L-1+BA0.5mg ·L-1+2,4-D 2 mg·L-1 for primary callus induction and MS+2,4-D10mg ·L-1+NAA 0.5mg·L-1 for embryogenic callus induction. Whitish-yellow, bright, fresh, incompact and coincident particle embryogenic calli were obtained on medium supplemented with 10 mg ·L-1 putrescine. Embryogenic calli can be induced within 70 days, and calli need be transfered to fresh medium within 60 days for subculture. Phytohormones free medium was used to induce somatic embryoid. Embryogenic cell mass formed in the 7~8th day and globular embryo, pear-shaped embryo in the 10~14th day, club-shaped embryo in the 21th day and banana-shaped embryo in the 28~30th day.2. Medium MS+2,4-D10 mg·L-1+NAA 0.5 mg·L-1+Put 10 mg·L-1 was used to induced embryogenic callus from primary callus, and embryogenic callus subcultured on it maintained high embryogenesis competence after subculturing 4 times. That indicated that putrescine effected on callus embryogenic competence containing in some certain extent.3. The endogenous phytohormones and polyamines levels of cultures in different phase were determined by means of High Performance Liquid Chromatography (HPLC), and the results indicated that IAA level raised rapidly after primary calli transformed to embryogenic callus induction medium. Both IAA and GA3 maintained high level when embryogenic callus emerged, which suggested that high level of IAA+GA3 was related to embryogenic calli emerging. Putrescine was the predominant type endogenous polyamines during the induction of embryogenic callus. And high putrescine content maintained until embryogenic calli formed, while the contents of Spd and Spm were low. We supposed that high ratio of Put/ (Spd+Spm) in callus was favor of embryogenic cell...