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BACKGROUND Xanthoceras sorbifolia Bunge is a valuable oilseed tree that has linoleic acid-rich seed oil. Microsomal oleate desaturase ( FAD2; EC 1.3.1.35) is responsible for the conversion of oleic acid to linoleic acid during fatty acid synthesis. In this study, XsFAD2 was cloned from developing embryos of X. sorbifolia. RESULTS XsFAD2 contained three histidine boxes, a C-terminal endoplasmic reticulum retrieval motif, and five putative transmembrane domains representing the characteristics of membrane-bound fatty acid desaturase. XsFAD2 expression in yeast cells resulted in linoleic acid (18:2) and palmitolinoleic acid (16:2) production, confirming the biological activity of the enzyme encoded by XsFAD2. These fatty acids are not normally present in wild-type yeast. Phylogenetic analysis indicated that XsFAD2 is located in a subgroup of FAD2 enzymes specifically or highly expressed in developing seeds. The expression level of XsFAD2 in seeds was much higher than those in leaves and petals. Furthermore, XsFAD2 expression pattern correlated well with linoleic acid accumulated in seeds. CONCLUSION Results suggested that XsFAD2 is responsible for the high linoleic acid content in X. sorbifolia seed oil. This study provides insight on the regulation mechanism of fatty acid synthesis in X. sorbifolia seeds and a valuable gene for improving the oil quality in oilseed trees. © 2013 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

There are abundant germplasm resources of drought resistant trees in China. It is difficult for foresters to evaluate and screen excellent germplasm that is suitable for various drought adverse circumstances. In this study, four tree species from different provenances, namely Amygdalus davi-diana , Prunus sibirica , Salix gordejevii , and Caryopteris mongolica , were used as test materials. Four soil regions, namely Dalad Banner, Siziwang Banner, Kouhezi town and Liujiazi town of Kulun Banner in the Central and Eastern Inner Mongolia Autonomous Region were selected as multi-point experiment sites to analyze the growth and physiological status of different tree species and provenances. The additive main effects and multiplicative interaction model was used to evaluate the regional adaptability and stability of the germplasm. The growth and physiological indices of four tree species differed between provenances and locations. Soil conditions (potassium content, nitrogen content, and pH) and climate conditions (annual average temperature, precipitation, and potential evaportranspiration) in different locations all influenced the growth of different provenance species. Concerning tree species, S. gordejevii and C. mongolica are more adapted to the sandy loam and chestnut soil of Dalad Banner and Siziwang Banner. A. davidiana and P. sibirica L. are more adapted to the loess and aeolian sandy soil of Kouhezi town and Liujiazi town. Concerning tree provenances, A. davidiana of Tuzuo, P. sibirica of Ningcheng and Yuanzhou, S. gordejevii of Lanqi, and C. mongolica of Jingbian displayed higher regional stability and better growth adaptability, indicating their suitability for afforestation in similar areas.