Background:
Jatropha curcas is recognised as a new energy crop due to the presence of high amount of oil in its seeds which can be converted into biodiesel. The quality and performance of the biodiesel depends on the chemical composition of the fatty acids present in the oil. The fatty acids profile of the oil has a direct impact on ignition quality, heat of combustion and oxidative stability. An ideal biodiesel composition should have more of monounsaturated fatty acids and less of polyunsaturated acids. Jatropha seed oil contains 30%-50% polyunsaturated fatty acids (mainly linoleic acid) which negatively impacts the oxidative stability and causes high rate of NOx emission.
Results:
FAD2 (1-acyl-2-oleoyl-sn-glycero-3-phosphocholine Delta 12-desaturase) is the key enzyme responsible for the production of linoleic acid in plants. We identified three putative delta 12 fatty acid desaturase genes (JcFAD2s) in Jatropha through genome-wide analysis and down-regulated the expression of one of these genes JcFAD2-1 in a seed-specific manner by RNA interference (RNAi) technology. The resulting JcFAD2-1 RNAi transgenic plants showed a dramatic increase of oleic acid (>78%) and a corresponding reduction in polyunsaturated fatty acids (<3%) in its seed oil. The control Jatropha had around 37% oleic acid and 41% polyunsaturated fatty acids respectively. This indicates that FAD2-1 is the major enzyme responsible for converting oleic acid to linoleic acid in Jatropha. Due to the changes of fatty acids profile, the oil of the JcFAD2-1 RNAi seed was estimated to yield a cetane number as high as 60.2 that are similar to the required cetane number for conventional premium diesel fuels (60) in Europe. The presence of high seed oleic acid did not have a negative impact on other Jatropha agronomic traits based on our preliminary data of T0 plants under greenhouse conditions. Further we developed a marker-free system to generate the transgenic Jatropha that will help reduce the public concerns for environmental issues in genetically modified plants.
Conclusion:
In this study we got seed specific JcFAD2-1 RNAi transgenic Jatropha without selectable marker. We successfully increased the proportion of oleic acid versus linoleic in Jatropha through genetic engineering enhancing its oil quality.Source:
http://www.biotechnologyforbiofuels.com/rss/