ABSTRACT
The delta-12 fatty acid desaturase (Δ¹² FAD or FAD2) is a key enzyme that catalyzes oleic acid to linoleic acid by dehydrogenation at Δ¹² position of fatty acid carbon chain. In peanut, reduction or loss of FAD2 activity could enhance the relative content of oleic acid in kernels, and improve the quality and oxidation stability of peanut kernels and products. RNA interference (RNAi) technology could lead to non-expression or down-regulated expression of AhFAD2 gene. We constructed two RNA interference expression vectors with the inverted repeat sequence of partial AhFAD2 gene, which were driven separately by cauliflower mosaic virus (CaMV) 35S promoter or soybean agglutinin lectin seed-specific promoter. Homozygous transgenic lines carrying the two constructs stably in genetics were developed by peanut genetic transformation. There were no significant differences between the transgenic lines and the control through investigating the main agronomic traits. We analyzed the transcriptional level expression of AhFAD2 gene in transgenic lines and the control by real-time fluorescence quantitative PCR (qRT-PCR). The results suggested that the target genes of transgenic lines were likely suppressed by RNA interference, but showed different transcriptional levels in different peanut transgenic lines. Compared with untransformed lines, the resulting down-regulation of AhFAD2 gene resulted in a 15.09% or 36.40% increase in oleic acid content in the seeds of transformed HY23 and FH1 lines respectively, and the content of linoleic acid decreased by 16.19% or 29.81%, correspondingly, the ratio of oleic acid and linoleic acid (O/L) improved by 38.02%, 98.10%. The oleic acid content had significant differences between the two transformation constructs, and also among different transgenic lines. Moreover, the inhibition effect of RNAi was more obvious in the transgenic lines with FH1 as the receptor, and with transformation structure driven by seed specific promoter. The suppressed expression of AhFAD2 gene enabled the development of peanut fatty acid, which indicated that RNA interference would be a reliable technique for the genetic modification of peanut seed quality and the potential for improvement of other traits as well.
ABSTRACT
OBJECTIVE:To improve the quality standard of Jianpi zhixiening granules. METHODS:TLC was applied for qual-itative identification of Scutellaria baicalensis,Crategi Fructus,Lonicerae japonicae,Codonopsis Radix,Nelumbo nucifera,Copti-dis Rhizoma. The contents of berberine hydrochloride and baicalin were determined by HPLC. The determination was performed on Shimadzu VP-ODS column with mobile phase consisted of methanol-acetonitrile-water (46:30:42,V/V/V,berberine hydrochlo-ride))(0.1% sodium dodecylsulphate,0.1% phosphoric acid,methanol-0.4% phosphoric acid(50:50,V/V,baicalin)at the flow rate of 1.0 mL/min. The detection wavelengths were set at 265 nm (berberine hydrochloride) and 280 nm (baicalin). The column temperature was 30 ℃,and sample size was 10 μL. RESULTS:TLC spots of S. baicalensis,Crategi Fructus,L. Japonicae,Co-donopsis Radix,N. nucifera,Coptidis Rhizoma were clear and well-separated without negative interference. The linear ranges of berberine hydrochloride and baicalin were 6.67-33.34 μg/mL(r=0.9998)and 7.7-38.7 μg/mL(r=0.9999). RSDs of precision,sta-bility and reproducibility tests were all lower than 1.0% . The recoveries were 96.5% -99.9%(RSD=1.2% ,n=6)and 101.1%-102.9%(RSD=0.6%,n=6). CONCLUSIONS:Improved standard can be used for quality control of Jianpi zhixiening granules.