Plant & Animal Genomes XIII Conference

January 15-19, 2005
Town & Country Convention Center
San Diego, CA

Sw4.1, The Major QTL For Seed Weight Variation In Tomato: Mapping And Characterization During Seed Development.

Cintia H. Orsi , Steven D. Tanksley

  Tomato Genetics Cooperative, Cornell University, 252 Emerson Hall, Ithaca, NY 14853-1901, USA

Sw4.1 was described in previous work as the major QTL for seed weight/size variation in tomato, explaining up to 54% of the variation between Lycopersicon esculetum (big seeds) and L. pimpinellifolium (small seeds). Genetic, developmental and association studies have been done to identify the gene and characterize the gene action. F2-population, derived from a cross between TA209 and TA2080 (NILs for Sw4.1 region), was used for high-resolution mapping with PCR-based markers (CAPS, dCAPS, deletion) in the Sw4.1 region of chromosome 4. The most significant marker explains 81% of the variation in seed length and 62% in seed weight. This marker was used for an association genetics study in wild accessions of L. esculentum var. cerasiforme . Polymorphism for this marker showed significant associations with seed weight, width, area and perimeter in these populations. Developmental studies of the Sw4.1 NILs reveal that the effects of the Sw4.1 QTL begin at 15 days after pollination (DAP; p<0.05). Eventual cloning of the Sw4.1 QTL should shed light on the evolutionary and molecular processes that have lead to increases in seed size associated with domestication.
*Supported by grants from USDA-NRI, NSF and Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq)-BRAZIL