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Sequence composition and genome organization of maize
Joachim Messing1, Arvind K Bharti, Wojciech M Karlowski
1Plant Genome Initiative at Rutgers, Waksman Institute, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA. messing@mbcl.rutgers.edu
Summary
Maize (corn) sequencing reveals approximately 59,000 genes, more than any other organism. This study provides insights into gene families and significant gene loss since its tetraploid ancestor.
Area of Science:
- Plant Genetics
- Genomics
- Molecular Biology
Background:
- Maize (Zea mays L. ssp. mays) is a vital crop and a model organism for plant genetics research.
- Understanding the maize genome's organization is crucial for crop improvement and fundamental biological studies.
- The maize genome is approximately 80% the size of the human genome.
Purpose of the Study:
- To gain global insight into the organization of the maize genome.
- To identify and characterize genes and transposable elements in maize.
- To understand the evolutionary history and gene content of the maize genome.
Main Methods:
- Sequencing the ends of large insert bacterial artificial chromosome (BAC) clones.
- Analyzing 307 Mb of cumulative sequence data.
- Utilizing ordered BAC clones for gene mapping and positional information.
Main Results:
- Repeat sequences constitute 58% of the analyzed maize genome, while genic regions comprise 7.5%.
- A conservative estimate predicts around 59,000 genes in maize, exceeding that of any other sequenced organism.
- Approximately one-third of maize genes appear to be organized in tandemly arrayed families.
- Significant gene loss has occurred since maize's tetraploidization, with fewer than half of the genes retaining two orthologous copies.
Conclusions:
- The maize genome is large and complex, with a high gene count and substantial repetitive elements.
- Positional information from BAC clones aids in understanding gene organization and family structures.
- Evidence suggests extensive gene loss and rediploidization following an ancient tetraploidization event in maize evolution.