Mapping and analysis of quantitative trait loci for grain oil content and agronomic traits using AFLP and SSR in sunflower (Helianthus annuus L.)

Abstract

Crosses were made between two inbred lines of sunflower. Parents and 118 F(3) families were planted in the field in a randomized complete block design in two replications. Genetic control for some agronomical traits: grain weight by plant (GWP), 1,000-grain weight (TGW), percentage of oil in grain (POG) and sowing to flowering date (STF) was investigated in F(3) families and their parents. Genetic variability was observed among the 118 F(3) families for all the traits studied. Genetic gain was obtained when the best F(3) family, or the mean of 10% of the selected families was compared with the best parent for GWP, TWG and POG. Heritability was 0.23 for GWP, 0.55 for TGW, 0.57 for POG and 0.32 for STF. A set of 244 F(3) families from the same cross, including the above 118 mentioned families and their two parents, were screened with 276 AFLP and microsatellite markers and a linkage map was constructed based on 170 markers. Two putative QTLs for the GWP trait ( gmp), one QTL for TGW ( tgw), six QTLs for POG ( pog) and two for STF ( stf) were detected. The percentage of phenotypic variance explained by each QTL ranged from 2.6% to 70.9%. The percentage of total phenotypic variance explained was 50.7% for GWP, 5.4% for TGW, 90.4% for POG and 89.3% for STF. Although these regions need to be more-precisely mapped, the information obtained should help in marker-assisted selection.

Genetic Control of Storage Oil Synthesis in Seeds of Arabidopsis

“…With the advent of molecular markers and the development of quantitative trait loci (QTL) mapping procedures, genes that control storage lipid synthesis can be identified and marker-assisted selection used to move beneficial QTL alleles into elite agricultural genotypes in oilseed breeding programs (Lande and Thompson, 1990). QTL analyses of oil content have been made in a number of crops, including oilseed rape (Brassica napus; Ecke et al, 1995;Burns et al, 2003), soybean (Glycine max; Lee et al, 1996;Csanadi et al, 2001), maize (Zea mays; Alrefai et al, 1995), and sunflower (Helianthus annuus; Mokrani et al, 2002;Leon et al, 2003). An analysis of groat oil content in oats revealed the presence of a small number of QTLs and an association between the major QTL and the plastidic acetyl-CoA carboxylase gene (Kianian et al, 1999).…”

Genotypic variation and identification of QTLs for agronomic traits, using AFLP and SSR markers in RILs of sunflower (Helianthus annuus L.)

“…The genomic DNA of the RILs and their parents was isolated according to method of extraction and purification protocols presented by Fulton et al (1995). The AFLP procedure was conducted as reported by Mokrani et al (2002).…”

“…For the first QTL (stf-4-1), alleles having positive effects come from 'PAC-2' parent, whereas for the two others come from 'RHA-266''. Recently, two QTLs presenting 89% of TR 2 for this trait were identified by Mokrani et al (2002), but the lack of common markers make it difficult to compare the maps position of the QTLs. Six QTLs associated with growing degree days to flowering and photoperiod response are also reported .…”

“…SSRs, called microsatellites, are also used as molecular markers. Their polymorphisms have shown high efficiency and are used for genetic mapping, population and evolutionary studies, as well as for fingerprinting and pedigree analysis in different species (Plaschke et al 1995;Rongwen et al 1995;Guilford et al 1997;Tang et al 2002;Mokrani et al 2002). SSR markers are now recognized as an efficient molecular marker for giving information at single locus.…”

“…Starting a programme of markerassisted selection becomes possible after the identification of QTLs for traits of interest. QTLs controlling important traits such as in vitro regeneration parameters (Flores Berrios et al 2000a-c), grain weight per plant (GWP), 1,000-grain weight (TGW), percentage of oil in grain (POG) and STF date (Mestries et al 1998;Mokrani et al 2002;Leon et al 2003), resistance to downy mildew and black stem (Rachid Al-Chaarani et al 2002), tolerance to Sclerotinia sclerotiorum (Mestries et al 1998;Bert et al 2002), as well as resistance to Orobanche Race E (Tang et al 2003b) and physiological parameters (Hervé et al 2001) are detected in sunflower.…”