title: Identification of QTLs associated with oil content and mapping FAD2 genes and their relative contribution to oil quality in peanut (Arachis hypogaea L.).
abstract: BACKGROUND
  Peanut is one of the major source for human consumption worldwide and its seed contain approximately 50% oil. Improvement of oil content and quality traits (high oleic and low linoleic acid) in peanut could be accelerated by exploiting linked markers through molecular breeding. The objective of this study was to identify QTLs associated with oil content, and estimate relative contribution of FAD2 genes (ahFAD2A and ahFAD2B) to oil quality traits in two recombinant inbred line (RIL) populations.
  
  
  RESULTS
  Improved genetic linkage maps were developed for S-population (SunOleic 97R × NC94022) with 206 (1780.6 cM) and T-population (Tifrunner × GT-C20) with 378 (2487.4 cM) marker loci. A total of 6 and 9 QTLs controlling oil content were identified in the S- and T-population, respectively. The contribution of each QTL towards oil content variation ranged from 3.07 to 10.23% in the S-population and from 3.93 to 14.07% in the T-population. The mapping positions for ahFAD2A (A sub-genome) and ahFAD2B (B sub-genome) genes were assigned on a09 and b09 linkage groups. The ahFAD2B gene (26.54%, 25.59% and 41.02% PVE) had higher phenotypic effect on oleic acid (C18:1), linoleic acid (C18:2), and oleic/linoleic acid ratio (O/L ratio) than ahFAD2A gene (8.08%, 6.86% and 3.78% PVE). The FAD2 genes had no effect on oil content. This study identified a total of 78 main-effect QTLs (M-QTLs) with up to 42.33% phenotypic variation (PVE) and 10 epistatic QTLs (E-QTLs) up to 3.31% PVE for oil content and quality traits.
  
  
  CONCLUSIONS
  A total of 78 main-effect QTLs (M-QTLs) and 10 E-QTLs have been detected for oil content and oil quality traits. One major QTL (more than 10% PVE) was identified in both the populations for oil content with source alleles from NC94022 and GT-C20 parental genotypes. FAD2 genes showed high effect for oleic acid (C18:1), linoleic acid (C18:2), and O/L ratio while no effect on total oil content. The information on phenotypic effect of FAD2 genes for oleic acid, linoleic acid and O/L ratio, and oil content will be applied in breeding selection.
authors.affiliation: US Department of Agriculture-Agricultural Research Service, Crop Protection and Management Research Unit, Tifton, GA, USA. m.pandey@cgiar.org.|International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Hyderabad, India. m.pandey@cgiar.org.|Department of Plant Pathology, University of Georgia, Tifton, GA, USA. m.pandey@cgiar.org.
authors.forename: Manish K
authors.initials: MK
authors.lastname: Pandey
authors.affiliation: US Department of Agriculture-Agricultural Research Service, Plant Genetic Resources Conservation Unit, Griffin, GA, USA. mingli.wang@ars.usda.gov.
authors.forename: Ming Li
authors.initials: ML
authors.lastname: Wang
authors.affiliation: US Department of Agriculture-Agricultural Research Service, Crop Protection and Management Research Unit, Tifton, GA, USA. lxqiao73@163.com.|Department of Plant Pathology, University of Georgia, Tifton, GA, USA. lxqiao73@163.com.|College of Life Science, Qingdao Agricultural University, Qingdao, China. lxqiao73@163.com.
authors.forename: Lixian
authors.initials: L
authors.lastname: Qiao
authors.affiliation: US Department of Agriculture-Agricultural Research Service, Crop Protection and Management Research Unit, Tifton, GA, USA. supingfeng1972@gmail.com.|Department of Plant Pathology, University of Georgia, Tifton, GA, USA. supingfeng1972@gmail.com.|College of Bioscience and Biotechnology, Qiongzhou University, Sanya, China. supingfeng1972@gmail.com.
authors.forename: Suping
authors.initials: S
authors.lastname: Feng
authors.affiliation: US Department of Agriculture-Agricultural Research Service, Crop Protection and Management Research Unit, Tifton, GA, USA. pkhera@uga.edu.|International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Hyderabad, India. pkhera@uga.edu.|Department of Plant Pathology, University of Georgia, Tifton, GA, USA. pkhera@uga.edu.
authors.forename: Pawan
authors.initials: P
authors.lastname: Khera
authors.affiliation: US Department of Agriculture-Agricultural Research Service, Crop Protection and Management Research Unit, Tifton, GA, USA. huixu@uga.edu.|Department of Plant Pathology, University of Georgia, Tifton, GA, USA. huixu@uga.edu.|Peanut Research Institute, Shandong Academy of Agricultural Sciences, Qingdao, China. huixu@uga.edu.
authors.forename: Hui
authors.initials: H
authors.lastname: Wang
authors.affiliation: US Department of Agriculture-Agricultural Research Service, Plant Genetic Resources Conservation Unit, Griffin, GA, USA. brandon.tonnis@ars.usda.gov.
authors.forename: Brandon
authors.initials: B
authors.lastname: Tonnis
authors.affiliation: US Department of Agriculture-Agricultural Research Service, Plant Genetic Resources Conservation Unit, Griffin, GA, USA. elle.barkley@ars.usda.gov.
authors.forename: Noelle A
authors.initials: NA
authors.lastname: Barkley
authors.affiliation: Department of Agronomy, University of Florida, Gainesville, FL, USA. wangjp@ufl.edu.
authors.forename: Jianping
authors.initials: J
authors.lastname: Wang
authors.affiliation: US Department of Agriculture-Agricultural Research Service, Crop Genetics and Breeding Research Unit, Tifton, GA, USA. corley.holbrook@ars.usda.gov.
authors.forename: C Corley
authors.initials: CC
authors.lastname: Holbrook
authors.affiliation: Department of Plant Pathology, University of Georgia, Tifton, GA, USA. spotwilt@uga.edu.
authors.forename: Albert K
authors.initials: AK
authors.lastname: Culbreath
authors.affiliation: International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Hyderabad, India. r.k.varshney@cgiar.org.
authors.forename: Rajeev K
authors.initials: RK
authors.lastname: Varshney
authors.affiliation: US Department of Agriculture-Agricultural Research Service, Crop Protection and Management Research Unit, Tifton, GA, USA. baozhu.guo@ars.usda.gov.|Department of Plant Pathology, University of Georgia, Tifton, GA, USA. baozhu.guo@ars.usda.gov.
authors.forename: Baozhu
authors.initials: B
authors.lastname: Guo
mesh_terms: D010367:Arachis / Q000201:enzymology / Q000235:genetics*; D001947:Breeding; D002874:Chromosome Mapping; D004843:Epistasis, Genetic; D044943:Fatty Acid Desaturases / Q000235:genetics*; D063427:Food Quality; D017343:Genes, Plant; D056726:Genetic Association Studies; D010938:Plant Oils / Q000378:metabolism*; D040641:Quantitative Trait Loci
chemical_list: D010938:Plant Oils; D044943:Fatty Acid Desaturases; C040448:delta-12 fatty acid desaturase