Transplastomic tobacco plants expressing a fatty acid desaturase gene exhibit altered fatty acid profiles and improved cold tolerance

摘要

The possibility of altering the unsaturation\udlevel of fatty acids in plant lipids by genetic transformation\udhas implications for the stress tolerance of\udhigher plants as well as for their nutritional value and\udindustrial utilisation. While the integration and expression\udof transgenes in the plastome has several potential\udadvantages over nuclear transformation, very few\udattempts have been made to manipulate fatty acid\udbiosynthesis using plastid transformation. We produced\udtransplastomic tobacco plants that express a Delta9\uddesaturase gene from either the wild potato species\udSolanum commersonii or the cyanobacterium Anacystis\udnidulans, using PEG-mediated DNA uptake by protoplasts. Incorporation of chloroplast antibioticinsensitive\udpoint mutations in the transforming DNA\udwas used to select transformants. The presence of the\udtranscript and the Delta9 desaturase protein in transplastomic\udplants was confirmed by northern and western\udblot analyses. In comparison with control plants,\udtransplastomic plants showed altered fatty acid profiles\udand an increase in their unsaturation level both in leaves\udand seeds. The two transgenes produced comparable\udresults. The results obtained demonstrate the feasibility\udof using plastid transformation to engineer lipid\udmetabolic pathways in both vegetative and reproductive\udtissues and suggest an increase of cold tolerance in\udtransplastomic plants showing altered leaf fatty acid\udprofiles. This is the first example of transplastomic\udplants expressing an agronomically relevant gene\udproduced with the ‘‘binding-type’’ vectors, which do\udnot contain a heterologous marker gene. In fact, the\udtransplastomic plants expressing the S. commersonii\udgene contain only plant-derived sequences, a clear\udattraction from a public acceptability perspective.