Arabidopsis Fatty Acid Desaturase FAD2
Is Required for Salt Tolerance during Seed Germination and Early Seedling Growth.
The acyl-lipid desaturases screened in this study include 2 [omega]-6 fatty acid desaturases (FAD2
) and 1 [omega]-3 fatty acid desaturase (FAD7).
Bilyeu, "Combinations of mutant FAD2
and FAD3 genes to produce high oleic acid and low linolenic acid soybean oil," Theoretical and Applied Genetics, vol.
In comparison, enzymes in concern with fatty acid modification and oil accumulation encountered the most significant regulation, with oleate desaturase (FAD2), linoleate desaturase (FAD3), oleateD12-hydroxylase (FAH12, only expressed in Jatropha) and D12 fatty acid conjugase (FADX, only expressed in Vernicia) identified for this category.
Previous work has proved successive fatty acid desaturations in various oil plants, including the stearic acid to oleic acid conversion catalyzed by SAD, subsequent linoleic acid formation by FAD2, as well as a-linoleic acid or a-eleostearic by FAD3 and FADX, respectively.
In previous studies, FAD2 genes were identified as encoding w-6 fatty acid desaturases which catalyze the conversion of 18:1 oleic acid to 18:2 linoleic acid in soybeans [6, 11].
Browse, "Arabidopsis FAD2 gene encodes the enzyme that is essential for polyunsaturated lipid synthesis," Plant Cell, vol.
For example, three different microsomal [DELTA]12 oleate desaturase genes (FAD2s
) were reported for sunflower (Martinez-Rivas et al., 2001), and two microsomal FAD2s
were reported each for soybean (Heppard et al., 1996) and for cotton (Liu et al., 1997), while three different microsomal [omega]-3 desaturase genes (FAD3s) were reported for soybean (Bilyeu et al., 2003).
An Arabidopsis mutant JB9, with altered FAD2
activity, was developed and characterized by Lemicux et al.
The desaturation of C18:1 to C18:2 is accomplished by a desaturase enzyme (FAD2
) acting most effectively on a phosphatidylcholine derivative of C18:1 (Stymne and Stobart, 1987).
Because HO2 only marginally increased the C18:1 content of the seed oil but significantly increased leaf and root C18:1 contents it is unlikely that the second mutation also affected fad2
. The increase of C18:1 in the leaves indicates, that fad6, the plastidial oleic acid desaturase, might be affected by HO2.
The reading frames for both cDNA isolated from peanut for the oleoyl-PC desaturase (FAD2
), ahFAD2A and -B were placed within the pYES2 expression vector where they are regulated by the GAL1 operon.