Search

An Agrobacterium mediated transformation method was developed for the Thai rice variety, Pathumthani 1 (PT1), and the Indian rice variety, Pokkali (PKL). Various aspects of the transformation method, including callus induction, callus age, Agrobacterium concentration and co-cultivation period were examined, in order to improve transformation efficiency. Optimized transformation conditions were established using Agrobacterium strain EHA105, which carries a virulent plasmid, pCAMBIA1301. A modified Murashige and Skoog (MS) medium supplemented with 1 mg/l 2, 4-D and 0.5 mg/l picloram was optimized for callus induction. Three week old calli were used to co-cultivate with 0.8 -1 OD600 Agrobacterium for 30 min and the culture was continued on agar medium without antibiotics for 2 days. This method can be used to induce high quality calli within three weeks. Based on GUS determination, it was demonstrated that the transformation method was improved significantly, with a high level of transformation efficiency.Keywords: Agrobacterium tumefaciens, indica rice, mature seed-derived callus, rice transformation, transgenic riceAfrican Journal of Biotechnology Vol. 9(34), pp. 5488-5495, 23 August, 2010

Artemisinin is an anti-malarial sesquiterpene lactone isolated from Artemisia annua L., a traditional Chinese herb of the family Asteraceae. The plant contains relatively low artemisinin content, ranging from 0.01 to 0.8% of the plant dry weight, depending on the geographical origin, seasonal, and somatic variations. Ionizing radiation has been recognized as a powerful technique for plant improvement, especially in crop plants. This technique creates genetic variability in plants, which can be screened for desirable characteristics. Very little is known about the effect of gamma irradiation on the potential increase of artemisinin production in A. annua. In this study, 130 shoot tips excised from the population of in vitro A. annua plantlets (with an average leaf artemisinin content of 0.18 ± 0.09%) were exposed to 5 Gy 60Co gamma irradiation and subsequently transferred to a suitable medium for in vitro development of plantlets. The resulting 90 stable survived after four passages appeared to have a wide variation of artemisinin content, ranging from 0.02 to 0.68% of dry weight. All the viable plantlets were then transferred from the in vitro cultures to ex vitro conditions both in a greenhouse and an open field. A significant correlation was observed between artemisinin content among individual pairs of the vitro plantlets and ex vitro mature plants, with the correlation coefficient (R2) values of 0.915 for the greenhouse plants and 0.797 for the open field plants. Among these, the highest artemisinin-containing plant appeared to accumulate 0.84% artemisinin of dry weight in the open field, which is almost five times higher than the original plants. These results suggest that gamma irradiation with 5-Gy dose can produce viable variants of A. annua that can maintain the biosynthetic capability of artemisinin throughout the in vitro-ex vitro transfer and development of the first generation of mature plants.