The high oleate trait in the cultivated peanut [Arachis hypogaea L.]. I. Isolation and characterization of two genes encoding microsomal oleoyl-PC desaturases.

Jung, S. and Swift, D. and Sengoku, E. and Patel, M. and Teulé, F. and Powell, G. and Moore, K. and Abbott, A. (2000) The high oleate trait in the cultivated peanut [Arachis hypogaea L.]. I. Isolation and characterization of two genes encoding microsomal oleoyl-PC desaturases. Molecular and General Genetics , 263 (5). pp. 796-805.

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Plant oils rich in oleate are considered superior products compared to oils rich in polyunsaturated fatty acids. Peanut (A. hypogaea) is one of the major oilseed crops, and high oleate mutant varieties with as much as 85% oleate have been reported. We examined the possibility that this mutant phenotype resulted from reduction in the activity or the transcript level of microsomal oleoyl-PC desaturase [phosphatidylcholine desaturase]. Two independently generated high oleate mutants, M2-225 and 8-2122, and their partially isogenic lines with a normal oleate phenotype were used in this study. Two cDNA sequences coding for microsomal oleoyl-PC desaturases, ahFAD2A and ahFAD2B, have been isolated from the developing peanut seed with a normal oleate phenotype. Cultivated peanut is an allotetraploid, and sequence comparisons with the genes from the putative diploid progenitor species suggested that ahFAD2A and ahFAD2B are non-allelic, but homeologous genes originating from two different diploid species. Northern analysis showed that the transcripts of oleoyl-PC desaturases are highly abundant in both normal and high oleate peanut seeds in the second stage of development. Differential digestion of the RT-PCR products revealed a restriction site polymorphism between ahFAD2A and ahFAD2B, and allowed us to examine the level of transcript expressed from each gene. The results indicate that ahFAD2A is expressed in both normal and high oleate peanut seeds, but the steady state level of the ahFAD2B transcript is severely reduced in the high oleate peanut varieties. These data suggested that the reduction in ahFAD2B transcript level in the developing seeds is correlated with the high oleate trait.

Item Type: Article
Additional Information: The authors thank Dr. John Browse (Wash-ington State University) and his group for providing Arabidopsis FAD2 cDNA clones, and thank Dr. Gary Kochert (University of Georgia) and his group for providing diploid peanut genomic DNA samples. This work was supported by a grant from AgraTech Seeds Inc., Ashburn, Ga. All experiments presented in this work were performed in compliance with the relevant laws of USA.
Uncontrolled Keywords: Arachis hypogaea, Peanut, High oleate, Desaturase, Oilseed
Author Affiliation: Department of Biological Sciences, Clemson University, Clemson, SC 29634-1903, USA.
Subjects: Statistics and Experimentation > Experimentation
Crop Improvement
Divisions: Groundnut
Depositing User: Mr Arbind Seth
Date Deposited: 13 Oct 2012 08:25
Last Modified: 13 Oct 2012 08:25
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