Isolation and characterization of the Δ12-fatty acid desaturase in peanut (Arachis hypogaea L.) and search for polymorphisms for the high oleate trait in Spanish market-type lines

Lopez, Y. and Nadaf, H.L. and Smith, O.D. and Connell, J.P. and Reddy, A.S. and Fritz, A.K. (2000) Isolation and characterization of the Δ12-fatty acid desaturase in peanut (Arachis hypogaea L.) and search for polymorphisms for the high oleate trait in Spanish market-type lines. Theoretical and Applied Genetics, 101 (7). pp. 1131-1138.

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An understanding of the molecular mechanisms that are responsible for increased oleic acid accumulation would open avenues to alter peanut fatty acid composition and allow detection of polymorphic regions which can be used for marker assisted selection (MAS). Δ12-Fatty acid desaturase (FAD) was isolated and characterized from genotypes having a low or high oleic to linoleic acid O/L ratio – genotypes, Tamspan 90 (T-90) and F435–2-2 (F435), respectively. Southern blots showed three to four copies per haploid genome, and no major differences in organization between the two parental lines. Approximately 3525 bp was isolated from both genotypes, including a genomic walk toward the promoter region. The Δ12-Fad contains a putative intron, the coding region at the 3′ end, and an open reading frame (ORF) of 1140 bp encoding 379 amino acids. Comparisons of the coding sequences from the high and low oleic acid genotypes revealed several single nucleotide polymorphisms (SNPs). Two polymorphisms appear to be associated with the high O/L trait. The first is an ”A” insertion 442 bp after the start codon. The ”A” insertion shifts the amino acid reading frame, probably resulting in a truncated, inactive protein and the loss of one of three histidine boxes believed to be involved in metal ion complexation required for the reduction of oxygen. Another polymorphism at 448 bp from the start codon results in an amino acid change. The region containing the polymorphisms was amplified from leaf tissue of several independently derived backcross lines (IDBLs). Most high O/L lines had either the ”A” insertion or the amino acid substitution.

Item Type: Article
Additional Information: The authors wish to thank Scott Senseman for technical support and guidance in managing the gas chromatography, Michael Baring for his assistance in planting and harvesting the plant material, Metinee Srivatanakul and Piyawit Bureekharm for their dedication and carefulness preparing individual seeds for oil analysis, Wendy Lacken for technical help and reviewing of the manuscript, and L.T. Kin, Rose Dowling, K. Renganayaki, Umesh K. Reddy, Josefina Alcalá, Carolina Rangel, and Thomas Bui for their guidance in the laboratory. This work was supported in part by The Texas Peanut Producers Board and The Peanut CRSP, and U.S. Agency for International Development, under grant no. DAN-4048-G-0041–00. The experiments performed for this publication comply with the current status of USA’s laws.
Uncontrolled Keywords: Arachis hypogaea L., Δ12-Fatty acid desaturase, Genomic sequences, Oleic peanut, Single nucleotide polymorphisms (SNPs)
Author Affiliation: Department of Soil and Crop Sciences, Texas A&M University,USA H.L. Nadaf, University of Agricultural Sciences,India
Subjects: Crop Improvement
Plant Physiology and Biochemistry > Plant Physiology
Divisions: Groundnut
Depositing User: Mr Arbind Seth
Date Deposited: 13 Oct 2012 08:03
Last Modified: 13 Oct 2012 08:03
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