Cloning, Characterization and Expression Analysis of a Stearoyl-ACP Desaturase Gene from Arachis Hypogaea.
ABSTRACT Stearoyl-ACP desaturase (SAD), which catalyzes the first desaturation reaction of the most common pathway of unsaturated fatty acid synthesis in plants, plays a key role in determining the ratio of saturated to unsaturated fatty acids. Using rapid amplification of cDNA ends (RACE) and a peanut cDNA library we had previously constructed, we isolated a 1499 bp cDNA of the SAD gene containing a 1218 bp complete open reading fragment (ORF). Sequence analysis revealed that peanut SAD had a high level of nucleotide and amino acid sequence homology to SAD from other plants. Characteristics of the deduced protein were predicted and analyzed using bioinformatic methods. Phylogenetic analysis showed that three different types of delta-9 fatty acid desaturases form separate clades, indicating that the three isozymes may have evolved independently. Expression analysis via real-time PCR indicated that expression levels of the SAD gene were markedly distinct in different peanut tissues and varieties. The results of the expression analysis in this study, combined with existing research, suggest that SAD may be involved in the regulation of plant seed growth and development.
- SourceAvailable from: Xiang Lu
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- "The quality and quantity of the storage lipids synthesized in developing seeds depends on a number of enzymes that participate in FA synthesis and TAG assembly through the Kennedy pathway . Although some of the individual enzymes and genes involved in these processes are known [2–5], and changes in TAG quality or yield have been made by genetic manipulation [6–9], little is known about the overall expression and regulation proﬁles of genes involved in peanut lipid biosynthesis [10–12]. To investigate the molecular basis of storage lipid accumulation during seed development it is necessary to understand the physiological mechanisms that affect the oil content in seeds and identify the rate-limiting enzymes that regulate storage lipid biosynthesis [13,14]. "
ABSTRACT: Peanuts are one of the most important edible oil crops in the world. In order to survey key genes controlling peanut oil accumulation, we analyzed the seed transcriptome in different developmental stages of high- and low-oil peanut varieties. About 54 million high quality clean reads were generated, which corresponded to 4.85 Gb total nucleotides. These reads were assembled into 59,236 unique sequences. Differential mRNA processing events were detected for most of the peanut Unigenes and found that 15.8% and 18.0% of the Unigenes were differentially expressed between high- and low-oil varieties at 30 DAF and 50 DAF, respectively. Over 1,500 Unigenes involved in lipid metabolism were identified, classified, and found to participate in FA synthesis and TAG assembly. There were seven possible metabolic pathways involved in the accumulation of oil during seed development. This dataset provides more sequence resource for peanut plant and will serve as the foundation to understand the mechanisms of oil accumulation in oil crops.PLoS ONE 09/2013; 8(9):e73767. DOI:10.1371/journal.pone.0073767 · 3.23 Impact Factor