Abstract
Fatty acids serve many functions in plants, but the effects of some key genes involved in fatty acids biosynthesis on plants growth and development are not well understood yet. To understand the functions of 3-ketoacyl-acyl-carrier protein synthase I (KASI) in tobacco, we isolated two KASI homologs, which we have designated NtKASI-1 and NtKASI-2. Expression analysis showed that these two KASI genes were transcribed constitutively in all tissues examined. Over-expression of NtKASI-1 in tobacco changed the fatty acid content in leaves, whereas over-expressed lines of NtKASI-2 exhibited distinct phenotypic features such as slightly variegated leaves and reduction of the fatty acid content in leaves, similar to the silencing plants of NtKASI-1 gene. Interestingly, the silencing of NtKASI-2 gene had no discernibly altered phenotypes compared to wild type. The double silencing plants of these two genes enhanced the phenotypic changes during vegetative and reproductive growth compared to wild type. These results uncovered that these two KASI genes had the partially functional redundancy, and that the KASI genes played a key role in regulating fatty acids synthesis and in mediating plant growth and development in tobacco.
Highlights
Fatty acids (FAs) are major components for cell or organelle membrane lipids, and precursors of other significant complex molecules including waxes and cutin
During FAs biosynthesis, the first committed step is catalyzed by acetyl-CoA carboxylase (ACCase), which converts acetyl-CoA to malonyl-CoA, and is condensed by a set of β-ketoacyl-ACP synthases (KASs), resulting in FA chain elongation [6,7,8]
After the assembly of EST fragments, two putative ketoacyl-acyl-carrier protein synthase I (KASI) fragments were identified with full-length coding regions, named as NtKASI-1 and NtKASI-2, respectively
Summary
Fatty acids (FAs) are major components for cell or organelle membrane lipids, and precursors of other significant complex molecules including waxes and cutin. The mitochondrion-specific mtKAS participating in FA synthesis for forming mitochondrial membranes has been isolated and characterized in Arabidopsis [19,20], but still very little is known in other plants Among these identified KASs, KASI, KASII and KASIII seem to be essential and exist broadly in plants. The genes encoding KASIII and KASII were extensively identified from various plants such as Spinach oleracea [21], Arabidopsis thaliana [22], Cuphea wrightii [23], Allium porrum [24], Pisum sativum [25], Helianthus annuus [12], Brassica napus [13] and Jatropha curcas [11,26] Their functions were partially documented in Jatropha curcas, sunflower and rapeseeds [11,12,13,26]. Results obtained in this study provide fundamental and important information for understanding the molecular functions of KASI genes in tobacco
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