Submitted to: HortScience
Publication Type: Peer reviewed journal
Publication Acceptance Date: 9/27/2007
Publication Date: 1/30/2008
Citation: Ahn, Y., Chen, G.Q. 2008. In vitro regeneration castor (ricinus communis l.) using cotyledon explants. HortScience. 55:10043-10049. Interpretive Summary: Castor seed triacylglycerols (TAGs) contains 90% ricinoleate (12-hydroxy-oleate) and is the only commercial source of hydroxy fatty acid that has numerous industrial applications. Due to the presence of ricin toxin and hyper-allergenic 2S albumins in the seed, it is desirable to remove the ricin and 2S albumins from castor seeds. We are investigating technologies to suppress the expression of ricin and 2S albumin genes in seed, thus making castor a safe crop.
Technical Abstract: A novel plant regeneration protocol was established for castor (Ricinus communis L.), an important oilseed crop. Mature seed-derived cotyledon explants produced adventitious shoots when placed on Murashige and Skoog (MS) medium containing thidiazuron (TDZ). The rate of shoot regeneration was maximal (approximately 25 shoots per explant) when explants were cultured on shoot induction medium supplemented with 5 µM TDZ and pre-incubated in the dark for the first 7 days before transferring to the day/night cycle (16/8 hours). Only the proximal ends of cotyledon explants produced adventitious shoots, although green calli were observed in cotyledon veins. After 4 weeks in culture, explants with well-developed shoot buds were transferred to MS medium without plant growth regulators for the shoot elongation and development. At approximately 4 months after culture initiation, shoots (2 cm in length) were transferred to root induction medium (MS medium supplemented with 5 µM indole-3-butyric acid) where they developed roots in 4 to 6 weeks. Plantlets were transferred to soil and acclimatized to greenhouse conditions. Histological analysis showed the adventitious induction of the shoots originated from the cortical and epidermal cell layers of the cotyledon explants.