Influence of soil salinity on the protein and fatty acid composition of the edible halophyte Halimione portulacoides.

As the worldwide population continues to rise, so does global demand for agricultural production. This scenario of uncertain food supply is exacerbated by the high salinization of soils worldwide, a serious constraint to crop productivity. In this context, there is an increasing need for alternative sustainable crops. Halophytes are thought to be a promising alternative food source due to their natural ability to grow in saline soils and their multiple potential uses in the food industry. In this study, the protein and fatty acid content of the halophyte Halimione (Atriplex) portulacoides (L.) was studied in different saline conditions. Although more studies are needed to explore the nutritional properties of H. portulacoides, the data presented here suggest that this halophyte should be considered as a promising food crop for saline agriculture.

Characterization of the acyl-ACP thioesterases from Koelreuteria paniculata reveals a new type of FatB thioesterase.

Koelreuteria paniculata is a deciduous tree, popular in temperate regions for its ornamental value, which accumulates unusual cyanolipids in its seeds. The seed oil of this plant is rich in the unusual cis-11-eicosenoic fatty acid (20:1, or gondoic acid), a monounsaturated oil of interest to the oleochemical industry. In higher plants, de novo fatty acid biosynthesis takes place in the plastids, a process that is terminated by hydrolysis of the thioester bond between the acyl moiety and the ACP by acyl-ACP thioesterases. The specificity of acyl-ACP thioesterases is fundamental in controlling the fatty acid composition of seed oil. To determine the mechanisms involved in fatty acid biosynthesis in K. paniculata seeds, we isolated, cloned and sequenced two cDNAs encoding acyl-ACP thioesterases in this plant, KpFatA and KpFatB. Both of them were expressed heterologously in Escherichia coli and characterized with different acyl-ACP substrates. The K. paniculata FatB2 displayed unusual substrate specificity, so that unlike most FatB2 type enzymes, it displayed preference for oleoyl-ACP instead of palmitoyl-ACP. This specificity was consistent with the changes in E. coli and N. benthamiana fatty acid composition following heterologous expression of this enzyme. KpFatB also showed certain genetic divergence relative to other FatB-type thioesterases and when modelled, its structure revealed differences at the active site. Together, these results suggest that this thioesterase could be a new class of FatB not described previously.