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Jim Holland
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My group is working on the genetic analysis of complex traits in maize and application of this knowledge to crop improvement. We work on the interface between emerging genomics technologies and complex phenotypes. Complex phenotypes are traits affected by numerous genes, environmental influences and interactions of genes and environments. These traits influence grain yield, ear rot resistances and even flowering time.

I call this research "phenomics," as the goal is a comprehensive understanding of how genes and environment interact to produce observable phenotypes.  We have recently moved toward this goal by providing the largest database ever available on genetic diversity in maize (Buckler et al. and McMullen et al., 2009).

We work in close collaboration with USDA-ARS groups at Ithaca, NY (Ed Buckler)and Columbia, MO (Mike McMullen and Sherry Flint-Garcia).   As a team, we developed the maize Nested Association Mapping (NAM) population, a set of 5,000 unique inbred lines representing a good sampling of maize genetic diversity.  Two new publications in Science (Buckler et al. and McMullen et al., 2009) report on the genetic structure of maize NAM population, implications for heterosis, and the genetic architecture of flowering time.

This is the world's largest, most comprehensive public genetic resource for complex trait mapping in any species. Seeds are publicly available at the USDA Genetics Maize Cooperation Stock Center in Illinois ( and genotype and phenotype information are publicly available at the project website,   The development of this population led to a "deep" mapping of many genes controlling flowering time and photoperiod variation in maize.   The work is being extended to understanding resistance to Southern Leaf Blight, in collaboration with Peter Balint-Kurti, also of the ARS Plant Science Research Unit in Raleigh

In addition, we conduct a classical breeding program for the improvement of resistance to Fusarium ear rot and mycotoxin contamination. We have bred lines that have improved ear rot resistance while maintaining yields. We also have a genetically-diverse population that is undergoing long-term selection to combining ear rot resistance, grain yield potential and lodging resistance.

Tapping into Corn's Tropical Diversity
(USDA-ARS News and Events, 2010)


Scientists Devise Efficient Way of Learning About Complex Corn Traits
(NC State University News Release, 2009)

Corn Research Unlocks Basis of Natural Diversity and Reveals Genetics of Flowering and Hybrid Vigor
(USDA-ARS News and Events, 2009)

ARS Produces Online Databases for Maize, Blueberries(USDA-ARS News and Events, 2008)