Specific and robust marker resources available for safflower breeding are scarce. The present research was aimed at developing a collection of genomic microsatellite (SSR) markers and to assess their informativeness. A genomic library enriched for AC-and AG-repeats was constructed from safflower DNA. Around 35% of the 768 clones that were isolated and sequenced contained SSR sequences. From these, 108 unique primer pairs were designed. The majority of the SSRs contained simple di-nucleotide motifs (77 of 108), most of them being perfect repeats (63 of 77). Reference allele length ranged from 95 to 414 bp, averaging 241.2 bp. The 108 SSRs were amplified in a set of ten safflower lines. From 88 SSR markers that amplified successfully, 64 of them detected polymorphism among the ten safflower lines genotyped. The number of alleles per locus ranged from 2 to 8 (mean value of 3.2), whereas heterozygosity ranged from 0.18 to 0.86 (mean value of 0.52). These genomic SSR markers will contribute to advance in safflower molecular breeding.

Sunflower (Helianthus annuus L.) seeds contain alpha-tocopherol as the major tocopherol derivative, which accounts for more than 900 g kg 21 total tocopherols. However, four sources of high gammatocopherol content (.850 g kg 21 ) have been developed. First studies on the lines LG-17 and T2100 concluded that the trait in both lines was determined by recessive alleles at the Tph2 locus. The objectives of the present research were (i) to conduct an allelic study on the other two lines, IAST-1 and IAST-540, (ii) to identify markers linked to the

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BackgroundTocopherols are natural antioxidants with both in vivo (vitamin E) and in vitro activity. Sunflower seeds contain predominantly alpha-tocopherol (>90% of total tocopherols), with maximum vitamin E effect but lower in vitro antioxidant action than other tocopherol forms such as gamma-tocopherol. Sunflower germplasm with stable high levels of gamma-tocopherol (>85%) has been developed. The trait is controlled by recessive alleles at a single locus Tph2 underlying a gamma-tocopherol methyltransferase (gamma-TMT). Additionally, unstable expression of increased gamma-tocopherol content in the range from 5 to 85% has been reported. The objective of this research was to determine the genetic basis of unstable expression of high gamma-tocopherol content in sunflower seeds.ResultsMale sterile plants of nuclear male sterile line nmsT2100, with stable high gamma-tocopherol content, were crossed with plants of line IAST-1, with stable high gamma-tocopherol content but derived from a population that exhibited unstable expression of the trait. F2 seeds showed continuous segregation for gamma-tocopherol content from 1.0 to 99.7%. Gamma-tocopherol content in F2 plants (average of 24 individual F3 seeds) segregated from 59.4 to 99.4%. A genetic linkage map comprising 17 linkage groups (LGs) was constructed from this population using 109 SSR and 20 INDEL marker loci, including INDEL markers for tocopherol biosynthesis genes. QTL analysis revealed a major QTL on LG 8 that corresponded to the gamma-TMT Tph2 locus, which suggested that high gamma-tocopherol lines nmsT2100 and IAST-1 possess different alleles at this locus. Modifying genes were identified at LGs 1, 9, 14 and 16, corresponding in most cases with gamma-TMT duplicated loci.ConclusionsUnstable expression of high gamma-tocopherol content is produced by the effect of modifying genes on tph2a allele at the gamma-TMT Tph2 gene. This allele is present in line IAST-1 and is different to allele tph2 present in line nmsT2100, which is not affected by modifying genes. No sequence differences at the gamma-TMT gene were found associated to allelic unstability. Our results suggested that modifying genes are mostly epistatically interacting gamma-TMT duplicated loci.

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