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United States Department of Agriculture

Agricultural Research Service

Title: Synthesis of Biodegradable Plastics in Alfalfa Plants

item Samac, Deborah

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: November 19, 2000
Publication Date: N/A

Technical Abstract: Plants can be used as living "factories" to produce biodegradable plastics from renewable resources. Alfalfa, with its high biomass production, is an ideal candidate for producing plastics as a value-added product. In this study, we engineered alfalfa to produce a biodegradable polymer, polyhydroxybutyrate (PHB). Three genes from Ralstonia eutropha encoding the eenzymes for synthesis of PHB engineered for plastid targeting were introduced into alfalfa by Agrobacterium-mediated transformation. GC and NMR analysis of leaf extracts confirmed the presence of polyhydroxybutyrate. Synthesis of PHB in the leaves of transgenic plants ranged from 8 to 350 ug/g of fresh weight representing 0.024% to 0.2% of the dry weight. Transmission electron microscopy of plants expressing all three genes revealed that PHB accumulated as agglomerations of electron- lucent granules of 0.2 to 0.5 um in the chloroplasts. DNA and RNA blot analysis confirmed the integration and expression of PHB biosynthetic pathway genes. Protein and enzyme assays are in progress and will be discussed in relation to PHB yield. Transgenic plants exhibited growth similar to wild-type suggesting that expression of PHB biosynthetic pathway genes at current levels in the plastids had no deleterious effect on growth and fertility. Transgenic alfalfa with highest concentrations of PHB were crossed with plants being developed for biomass production and F1 progeny are currently under investigation.

Last Modified: 4/18/2015
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