Plant & Animal Genome IX Conference

Workshop: Compositae
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QTL MAPPING FOR GROWING DEGREE DAYS TO FLOWERING AND PHOTOPERIOD RESPONSE IN SUNFLOWER (Helianthus annuus L.)

¹ Advanta Semillas SAIC, Balcarce Research Station. CC: 30. (7620) Balcarce, Pcia. de Bs. As., Argentina.

² Dep. of Agronomy, Iowa State University, Ames, IA 50011-1010, USA.

³ Mar del Plata University, (7620) Balcarce, Pcia. de Bs. As., Argentina.

In sunflower, the number of days from emergence to flowering (DTF) is a complex trait determined by the genotype, environmental conditions and interactions. Photoperiod and temperature have major effects on DTF and are an important sources of GxE interaction. The objectives of this study were to locate quantitative trait loci (QTL) associated with growing degree days (GDD) to flowering and photoperiod (PP) response in a sunflower population. Two hundred thirty-five F2-generation plants and their F2:3 and F2:4 progenies were evaluated in six environments. Detection of QTL was facilitated with an RFLP map of 205 loci and composite interval mapping. Six QTL in linkage groups A,B,F,I,J, and L were associated with GDD to flowering and accounted for 76% of the genotypic variation in the mean environment. QTL in linkage groups A and B accounted for 72% of the genetic variation. QTL x Environment (QTLxE) interactions were highly significant for linkage groups A,B,F and J. QTL in linkage groups A and B were highly dependent on PP. Also, QTL mapping of the ratio of the GDD required by a progeny to flower at PP of 12.1 and 15.0 hours, defined as photoperiod response (PPR), suggested that alleles at QTL in linkage groups A and B were responsive to PP. QTL in linkage groups F and J showed QTL x E interaction but the LOD values were not associated with PP. The knowledge of how these QTL influence the GDD for flowering and how they interact with the environment will facilitate marker-assisted selection.