Download - Maize

Compared with the genomes of other crops, single‐nucleotide polymorphism (SNP) frequency in maize is
high, with one SNP every 28–124 bp (Vroh Bi et al. 2006). Molecular characterization of >600 maize
inbred lines at CIMMYT has recently led to the discovery of SNP markers with no germplasm‐specific
biases and the identification of informative haplotypes (Lu et al. 2009; Yan et al. 2009). Based on
haplotype information, a versatile core set of inbreds that captures 90% of the haplotype diversity of the
entire panel has also been established. A maize database and resource for SNP discovery and trait
dissection, in which genotype and phenotype data can be accessed for diverse maize inbreds and
populations, has become available (Zhao et al. 2006). Strategies for formulating core collections using
passport, phenotypic, and molecular/biochemical data have been formulated at CIMMYT (Franco et al.
2006).
Researchable issues
Comprehensively characterizing the genetic richness and the phenotypic diversity of maize, and
identifying, by association mapping, novel, potentially useful alleles, haplotypes, allele
combinations, and donors for yield potential, tolerance to key abiotic/biotic‐stresses and
nutritional‐quality traits.
Identifying selection imprints and allele‐frequency clines across environmental gradients.
Establishing a pre‐competitive “commons” domain for delivery of diversity data and knowledge as
global public goods—which discourages intellectual property (IP) protection on raw materials and
basic knowledge required for maize breeding while encouraging the use of SI products for the
development of cultivars, irrespective of their IP status.
Leveraging top‐end information technology (IT) tools and expertise to design a researcher/breederoriented
web interface—for visualizing, querying, and mining trait, molecular, and geo‐referenced
passport data across the entire set of accessions in an integrated manner.
Mobilizing novel diversity into breeding programs: (1) via a pre‐breeding introgression pipeline that
assists maize breeders in the mobilization of novel alleles into their breeding programs; (2) by
strengthening/refining existing seed‐conservation and delivery operations.
Outputs
1. Phenotypic and molecular descriptions of conserved maize diversity generated and integrated with
geo‐referenced passport data, and packaged and delivered to the global maize community via a
researcher/breeder‐oriented MAIZE Diversity Portal.
An information‐rich data repository is made available on the web as a global public good, which
allows integrated queries of molecular, trait, and geo‐referenced passport data.
Identification of donors for internationally relevant priority traits:
o Biotic stresses: Diseases (e.g., maize streak virus, gray leaf spot, leaf blights, rusts, downy
mildews, banded leaf and sheat blight, stalk and ear rots, mycotoxins); Pests (e.g., stem
borers, maize weevil, large grain borer, nematodes); Striga
o Nutritional quality: Pro‐vitamin A, endosperm protein quality; kernel micronutrients
(especially zinc)
o Abiotic stresses: Drought, low N, high temperature, acidity/Al toxicity, waterlogging,
o Yield‐related traits
o High‐value specialty traits (e.g., oil)
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