Poster: Biotech Risk Assessment
Abs #
901: Transgenic Spirodela: a unique, low-risk, plant biotechnology system
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Presenter: |
Edelman, Marvin , marvin.edelman@weizmann.ac.il |
Authors | Edelman, Marvin (A) Vunsh, Ron (A) Li, Jihong (A) Hanania, Uri (A) Flaishman, Moshe (B) Perl, Avihai (B) | | Affiliations: |
(A): Weizmann Institute of Science, Department of Plant Sciences
(B): Agricultural Research Organization, The Volcani Center, Department of Fruit Tree Sciences
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The monocot family Lemnaceae is composed of small, aquatic, floating plants. Two of its genera, Lemna and Spirodela, are distributed worldwide and have biomass doubling times of 48-72h under controlled, axenic conditions. Reproduction is typically vegetative, with culture mass increasing exponentially until crowding sets in. Lemna, however, can also flower and produce seeds while Spirodela rarely do so. Spirodela oligorrhiza proliferates exclusively in a vegetative manner. Its protein content approaches 50% of its dry weight and is well balanced in essential amino acids. Our group at the Weizmann Institute has successfully induced a tissue culture cycle (callus formation and plant regeneration), taking about 3 months, in S. oligorrhiza. Several Agrobacterium vectors were applied at the callus stage resulting in stable transformed plants. Four different binary plasmids fused to different leaders were successfully used as vectors for transformation. The transgenic lines are stable in growth rate, transgene expression, and activity. This was confirmed over a period of 18 months and more than 150 biomass doublings, by DNA-DNA and immunoblot hybridizations, fluorescence measurements and antibiotic resistance. Expression of transgene products ranged from 0.005% to about 3% of total protein. Expression level is a function of the plasmid construct used rather than transgene copy number. A significant fraction of native transgene product can be programmed for excretion, dependant on the construct leader. Low-risk advantages of the Spirodela transgene system are: totally enclosed growth facilities; seedless plants means no live transgenic material outside the growth facility; Spirodela is edible, thus the engineered, dried plant can be the final biotech product.
