|
Lodging may be defined as rupture of the stalk below ear level. This
phenomenon reduces yield 5-20% worldwide, raises drying costs, and
exacerbates problems of volunteer plants emerging the following
season. To address this issue, we have further elucidated the genetic
architecture of stalk strength in maize using the Nested Association
Mapping Population (NAM). Previous analyses of four biparental
populations of F_2:3 families by Flint-Garcia et al. (2003) revealed
the utility of rind penetrometer resistance (RPR) in phenotyping stalk
strength as well as the complexity of its genetic architecture.
Surveying the allelic diversity, and utilizing the statistical power and
marker density available in the twenty-five biparental populations of
NAM, we have sought to confirm and supplement earlier analyses by
implementing the same RPR phenotyping method. Current data from a
single evaluation environment have mapped eleven QTLs accounting for 30% of the phenotypic variance across the twenty-five recombinant inbred populations. All QTL are shared by more than four NAM populations and eight of the eleven possess a series of positive and negative alleles with respect to the B73. Future analyses to enhance our understanding of stalk strength include replicated evaluation and genome-wide association mapping of RPR to exploit historical recombination in NAM founders.
|
