Overexpression of FAD2 promotes seed germination and hypocotyl elongation in Brassica napus

Abstract

The enzyme fatty acid desaturase 2 (FAD2) transforms oleic acid (C18:1) to linoleic acid (C18:2) in plants and as such is involved in fatty acid synthesis. It is also involved in plant development and self-defense, such as seed germination, leaf expansion and cold resistance. We have cloned the full coding region of the Brassica napus FAD2 gene and ectopically expressed it in B. napus expressing low levels of FAD2. Overexpression of FAD2 under the control of the CaMV 35S promoter resulted in an up-regulated FAD2 mRNA level in B. napus as expected. Further analysis revealed that the FAD2 transgenic lines varied greatly in terms of their physiological characteristics, such as enhanced seed germination and increased hypocotyl length, compared to non-transgenic plants, suggesting that up-regulated FAD2 can promote seed germination and hypocotyl elongation in B. napus. Our results demonstrate the possible roles of FAD2 in plant development and also provide a platform for further analysis of fatty acid synthesis in plants.

Quantitative Trait Locus Analysis of Seed Germination and Seedling Vigor in Brassica rapa Reveals QTL Hotspots and Epistatic Interactions

“…This QTL region on A05 is the major locus with QTLs for seed germination and seedling vigor under salt stress (Figure 2B ), suggesting a role of BrFAD2 in regulating germination and seedling vigor under salt stress. Besides the role of FAD2 gene in fatty acid desaturation, Wang et al ( 2010 ) reported that the up-regulation of the FAD2 gene enhanced seed germination and hypocotyl length in their study on FAD2 -transgenic and non-transgenic lines of the closely related species B. napus . In another study on the comparison of a fad2 mutant of A. thaliana with the wild type, a functional role of FAD2 was reported in increasing salt tolerance during seed germination and early seedling growth (Zhang et al, 2012 ).…”

The FAD2 Gene in Plants: Occurrence, Regulation, and Role

“…The biosynthetic pathway of fatty acids and lipids in plants is well presented in Figure 5 . Many enzymes in fatty acid biosynthesis had been biochemically characterized, as well as the encoding genes from plants like Brassica napus and Arabidopsis thaliana ( Slabas and Fawcett, 1992 ; Ohlrogge and Browse, 1995 ; Beisson et al, 2003 ; Wang et al, 2010 ). Fatty acids are normally synthesized by a fatty acid synthase (FAS) complex located in the plastids that uses acetyl-CoA as a precursor and malonyl-ACP as an elongator.…”

“…FAD2 overexpression modifies many physiological features in transgenic seedlings, like seed germination and hypocotyl elongation, but such effects could not be observed after transformation with genes other than fatty acid desaturases ( Wang et al, 2010 ). It was reported that fad2 mutants formed dwarf phenotypes at a temperature of 22°C in Arabidopsis, when compared with the wild type plant ( Miquel et al, 1993 ).…”

Influence of Oleic Acid Content on Yield in Winter Oilseed Rape

“…This is in accordance with the results of an Arabidopsis thaliana fad2 mutant (Miquel et al, 1993; Miquel and Browse, 1994) and HO Helianthus annuus (Garces et al, 1989). In fad2 ‐overexpressed Brassica napus a more rapid germination was observed (Wang et al, 2010). This increase was explained by means of the existence of a gibberellin‐responsive element in the fad2 promoter sequence.…”