Development of camelina enhanced with drought stress resistance and seed oil production by co-overexpression of MYB96A and DGAT1C

Abstract

Camelina (Camelina sativa, Cs) is an emerging crop for the production of biodiesel and biofeedstock. This study aims to develop transgenic plants that have the advantage of two traits: improved drought resistance and oil content. Three genes, CsMYB96A, CsMYB96B, and CsMYB96C, were isolated from camelina stem. The deduced amino acid sequence of the three CsMYB96s showed at least 93% identity with Arabidopsis MYB96. CsMYB96A, B, and C transcripts were detected in various camelina tissues. Fluorescence signal from the fusion of CsMYB96A: enhanced yellow fluorescent protein was confined to the nucleus of tobacco epidermal cells. Transactivation analysis of tobacco protoplasts revealed that CsMYB96A was a transcription activator. Wax biosynthesis genes such as camelina β-ketoacyl-CoA synthase 2, β-ketoacyl-CoA synthase 6, β-ketoacyl-CoA reductase 1-1, β-ketoacyl-CoA reductase 1-2, enoyl-CoA reductase, ECERIFERUM 1 and ECERIFERUM 3 were upregulated approximately 2 to 120 times by CsMYB96A, indicating that CsMYB96A was involved in the activating of cuticular wax synthesis on plant epidemics. Camelina diacylglycerol acyltransferase 1C (CsDGAT1C) has been shown to increased oil synthesis genes in Arabidopsis. When CsDGAT1C and CsMYB96A were co-overexpressed in camelina, total fatty acid levels in transgenic seeds increased by approximately 21%. In addition, the transgenic camelina plants showed improved resistance to drought stress. This result suggests that the transgenic camelina can be grown to produce biodiesel and biofeedstock in arid or semi-arid lands.