Identification of QTLs associated with oil content and mapping FAD2 genes and their relative contribution to oil quality in peanut (Arachis hypogaea L.).

Manish K Pandey,Pawan Khera,Baozhu Guo,Ming Li Wang,Brandon Tonnis,Lixian Qiao,Rajeev K Varshney,Suping Feng,Albert K Culbreath,C Corley Holbrook,Jianping Wang,Hui Wang,Noelle A Barkley

doi:10.1186/s12863-014-0133-4

Abstract

BackgroundPeanut 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.ResultsImproved 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.ConclusionsA 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.Electronic supplementary materialThe online version of this article (doi:10.1186/s12863-014-0133-4) contains supplementary material, which is available to authorized users.

Highlights

Peanut is one of the major source for human consumption worldwide and its seed contain approximately 50% oil
For the S-population, 206 mapped loci were distributed on 20 linkage groups (LGs) covering a total genome distance of 1780.6 cM and achieved a map density of 9.6 cM/loci
For the T-population, 378 loci were mapped onto 20 linkage groups covering a total map distance of 2487.4 cM with a map density of 7.0 cM/loci (Table 1, Additional files 3 and 4)

Summary

Introduction

Peanut is one of the major source for human consumption worldwide and its seed contain approximately 50% oil. In 2012, the global production was 41.18 m tons from an area of 24.70 m ha [1] It is one of the main oil crops of the world averaging about 50% oil content and it could be as low as less than 40% [2]. Fatty acid desaturase (FAD2) catalyzes the conversion of oleic acid to linoleic acid by adding a double bond to oleic acid [3] This enzyme is encoded by two homeologous genes, ahFAD2A and ahFAD2B, located on the A and B sub-genomes, respectively [4,5,6]. The mutant ahFAD2A gene had substitution (G:C to A:T) and ahFAD2B gene had insertion (A:T) of one base pair These mutations led to accumulation of more oleic acid (C18:1) and less linoleic acid (C18:2) making the peanut oil with high O/L ratio

Objectives

Methods

Results

Discussion

Conclusion