Quantitative Trait Loci for Tassel Traits in Maize

The inheritance of tassel traits in maize (Zea mays L.) is not well understood. This study was conducted to estimate the chromosomal location and magnitude of effect of major quantitative trait loci (QTL) affecting tassel branch angle (ANGLE), branches per tassel (BRANCH#), and tassel weight (TASSWT) in 200 S1 lines derived from a single F1 plant from a cross of Illinois High Oil (IHO) by Illinois Low Oil (Early Maturity) [ILO(EM)]. The restriction fragment length polymorphism (RFLP) genotypes of the 200 S1 lines were determined at 80 polymorphic loci. These lines were measured for ANGLE, BRANCH#, and TASSWT in replicated field trials during 1992 and 1993 at Urbana, IL. Composite interval mapping using selected markers as cofactors detected several QTL for each tassel trait. Six QTL located on chromosomes 2, 3, 5, 6, and 10 were significantly associated with ANGLE. They showed primarily dominant gene action and explained 43.1 and 50.7% of the phenotypic and genetic variance, respectively. Three QTL located on chromosomes 2, 4, and 7 were significantly associated with BRANCH#. They showed primarily additive gene action and explained 44.3 and 49.3% of the phenotypic and genetic variance, respectively. The QTL for BRANCH# on chromosome 7 explained 35.3% (R2) of the phenotypic variance. Seven QTL located on chromosomes 1, 2, 3, 4, and 7 were significantly associated with TASSWT. They showed primarily negative dominant gene action and explained 35.1 and 43.4% of the phenotypic and genetic variance, respectively. Most of the major QTL detected for these tassel traits were not associated with anthesis date (ANTH) in this population.