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Update on the Maize Genome Sequencing Project
On September 20, 2002, the National Science Foundation (NSF) announced the launch of the Maize Genome Sequencing Project. The momentum for this endeavor has been building within the maize (Zea mays) genetics and larger plant science community for several years. Reasons for launching a concerted effort at this time are at least 4-fold. First, advances in DNA sequencing technology now allow faster sequencing at a lower cost than in the past. Second, new high-resolution, high-throughput DNA fingerprinting methods should yield a minimum clone set colinear with the genetic map of the maize genome. Third, promising approaches to preparing fractions of the maize genome enriched for genes have been developed. Fourth, comparative analyses of maize with rice (Oryza sativa) or Arabidopsis suggest that the genome sequences of these two species will not be sufficient to understand the precise details of maize gene content and expression. This Update reviews the project goals and the expected deliverables deriving from the two funded consortia.
WHY SEQUENCE MAIZE?
The cereals, including maize and rice, account for 70% of food production worldwide, and in addition, maize is an economically important crop in the United States. Maize is also the best-studied and most tractable genetic system among the cereals, making it the premier model system for studying this important group of crops, as well as other monocots. Although cereals are of economic importance and a greater understanding of their genes will have great impact, much interesting biology can also be learned from these species. For example, the recent diversification of the grasses makes them an ideal collective system for dissecting genetic control of morphological and genomic diversity (for review, see Kellogg, 2001). Comparative analyses of several cereal genomes, including maize, rice, sorghum (Sorghum bicolor), wheat (Triticum aestivum), and barley (Hordeum vulgare), have shown extensive conservation of gene content and order at the level of the overall genetic map (Gale and Devos, 1998).
However, local rearrangements often interfere with microsynteny, providing evidence for the differentiation of grass genomes (Tikhonov et al., 1999; Keller and Feuillet, 2000; Dubcovsky et al., 2001; Fu and Dooner, 2002; Li and Gill, 2002; Song et al., 2002). These rearrangements include tandem gene duplications, small inversions, and translocations of...