| As an important cash crop, the cultivated peanut, Arachis hypogaea L., is mainly an oilseed crop for edible oil extraction in developing countries, whereas in developed nations, it is used primarily for food. Both oleate and linoleate are unsaturated fatty acids, constituting about80%of total fatty acids in peanut seeds. High oleate peanut not only has extended shelf life, but also bring about multiple health benefits, including reduced heat/brain trouble risks, improved sensitivity to insulin, and preventive or amelioration effects on inflammatory and tumorigenesis. Breeding for high oleate has therefore become one major objective of peanut quality improvement.In the present study, an optimized protocol for GC determination of fatty acids in peanut seeds, and NIRS models predictive of fatty acids were developed, and differentially expressed genes were isolated using large-seeded peanut line Lufeng2and its high oleate mutant. Major research results were listed below:1) For rapid and accurate determination of fatty acids in peanut seeds, the weight of sample, dilution factors and GC programs were optimized. Eventualliy, a53min protocol for analysis of8fatty acids in peanut seeds using5-20mg seed tissue was developed based on Gao and Zhang (2010). The protocol gave consistent results, regardless of sampling weights. For5mg seed tissue, the best dilution factor was2X, for10mg seed tissue,2-5X, and for20mg seed tissue,5-10X. Under the optimized conditions, peaks were well separated, and all of the eight fatty acids could be accurately determined. The protocol provides a rapid and reliable means for fatty acid determination in groundnut seeds, and may find wide utility in genetic improvement in fatty acid composition of the oilseed crop.2) F2seeds from4normal X high oleate crossed and freshly harvested peanut seeds were use d to establish calibration equations for predicating oleic, linoleic,palmitic acids and four harmful fatyy acids and IV, U/S and moisture content.The R2was94.67,95.72,86.36,83.71,94.90,73.53and93.62, and RMSECP was2.52,1.91,0.60,0.67,1.57,0.27and1.17. Among them, models for oleic and linoleic acid,Ⅳ and moisture content had R2higher than90, and much lower RMSECP, which may satisfy the need for quality selection, while U/S model possessed a R2value of73.52.The predictive error was-4.399～4.838,-2.011～1.874,-1.247～1.438,-1.634～1.420,-2.231～3.733,-0.533～1.396,-1.781～1.902, predictive relative error was0.562～9.687,0.055～7.010,0.642～12.72,0.636～11.464,0.217～4.145,1.582～17.934,0.122%～2.855%, respectively.Validation results showed that the NIRS models for oleic, linoleic, palmitic acid, IV and moisture had high quality, U/S and the4harmful fatty acids, due to their narrow range and low value, possessed average quality, and are yet to be improved. U/S, IV and moisture content models were established for the first time, providing selection tools for peanut genetic improvement in fatty acids. 3) Using large-seeded peanut line Lufeng2, its high oleic acid mutant and genefishing technology,17unique differentially expressed genes with molecular weight of105-665bp were isolated. Most of the genes showed high homology to sequences deposit in GenBank. Functions were mainly involved in chilling tolerance and disease resistance. However, we failed to find genes with direct implications in oleate trait expression. Ten of the sequences had no known functions, which deserve further investigation. |
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