Background
Jatropha curcas is an important biofuel crop due to the presence of high amount of oil in its seeds suitable for biodiesel production. Triacylglycerols (TAGs) are the most abundant form of storage oil in plants. Diacylglycerol O-acyltransferase (DGAT1) enzyme is responsible for the last and only committed step in seed TAG biosynthesis. Direct upregulation of TAG biosynthesis in seeds and vegetative tissues through overexpression of the DGAT1 could enhance the energy density of the biomass, making significant impact on biofuel production.ResultsThe enzyme diacylglycerol O-acyltransferase is the rate-limiting enzyme responsible for the TAG biosynthesis in seeds. We generated transgenic Jatropha ectopically expressing an Arabidopsis DGAT1 gene through Agrobacterium-mediated transformation. The resulting AtDGAT1 transgenic plants showed a dramatic increase in lipid content by 1.5- to 2 fold in leaves and 20–30 % in seeds, and an overall increase in TAG and DAG, and lower free fatty acid (FFA) levels compared to the wild-type plants. The increase in oil content in transgenic plants is accompanied with increase in average plant height, seeds per tree, average 100-seed weight, and seed length and breadth. The enhanced TAG accumulation in transgenic plants had no penalty on the growth rates, growth patterns, leaf number, and leaf size of plants.ConclusionsIn this study, we produced transgenic Jatropha ectopically expressing AtDGAT1. We successfully increased the oil content by 20–30 % in seeds and 1.5- to 2.0-fold in leaves of Jatropha through genetic engineering. Transgenic plants had reduced FFA content compared with control plants. Our strategy of increasing energy density by enhancing oil accumulation in both seeds and leaves in Jatropha would make it economically more sustainable for biofuel production.
The seed oil of Jatropha (Jatropha curcas L.) as a source of biodiesel fuel is gaining worldwide importance. Commercial-scale exploration of Jatropha has not succeeded due to low and unstable seed yield in semiarid lands unsuitable for the food production and infestation to diseases. Genetic engineering is promising to improve various agronomic traits in Jatropha and to understand the molecular functions of key Jatropha genes for molecular breeding. We describe a protocol routinely followed in our laboratory for stable and efficient Agrobacterium tumefaciens-mediated transformation of Jatropha using cotyledonary leaf as explants. The 4-day-old explants are infected with Agrobacterium tumefaciens strain EHA105 harboring pBI121 plant binary vector, which contains nptII as plant selectable marker and gus as reporter. The putative transformed plants are selected on kanamycin, and stable integration of transgene(s) is confirmed by histochemical GUS assay, polymerase chain reaction, and Southern hybridization.
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