ARS | Publication request: Phenotypic characterization and molecular mapping of a twin seeded trait of sorghum (Sorghum bicolor L. Moench)

Submitted to: American Society of Plant Biologists Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: February 28, 2009
Publication Date: March 2, 2009
Citation: Burow, G.B., Franks, C.D., Hayes, C.M., Burke, J.J. 2009. Phenotypic characterization and molecular mapping of a twin seeded trait of sorghum (Sorghum bicolor L. Moench [abstract]. American Society of Plant Biologists Southern Section Annual Meeting.

Technical Abstract: Naturally occurring mutants which produce two seeds per fertile floret known as “twin-seeded” have been reported for many years in sorghum. However, details about the morphological and molecular nature of the trait are limited. To better understand twin-seeded trait and its subsequent role in grain yield, morphological characterization and molecular mapping studies were conducted using a mutant mapping population from a cross between KFS4023 (twin-seeded line) and BTx623 (single seeded inbred line. KFS4023 had two sessile, fertile pistils surrounded by six stamens in the fertile floret and was categorized as a floral organ number mutant. KFS4023 and the twin-seeded F2’s, F3’s, expressed the “embryo out” phenotype, where seeds are positioned with embryo in each caryopsis oriented opposite each other. The twin-seeded trait was dominant, segregating in 3:1 ratio. Molecular mapping using microsatellite markers indicated that the twin-seeded locus localized to chromosome 6 and is bordered by markers Xtxp219 and Xtxp95, corresponding to a 20.3 cM interval. These results open up avenues for future cloning of the twin seededness gene and new investigations into the practical application of the trait in sorghum breeding.