This Article Full Text Full Text (PDF) Supplemental Research Data All Versions of this Article: gr.4249906v1 16/1/115    most recent Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Anderson, L. K. Articles by Gaut, B. S. Search for Related Content PubMed PubMed Citation Articles by Anderson, L. K. Articles by Gaut, B. S. Social Bookmarking                   What's this?

Letter

Uneven distribution of expressed sequence tag loci on maize pachytene chromosomes

¹ Department of Biology, Colorado State University, Fort Collins, Colorado 80523, USA ² Department of Ecology and Evolution, University of California, Irvine 92697-2525, California, USA

Examining the relationships among DNA sequence, meiotic recombination, and chromosome structure at a genome-wide scale has been difficult because only a few markers connect genetic linkage maps with physical maps. Here, we have positioned 1195 genetically mapped expressed sequence tag (EST) markers onto the 10 pachytene chromosomes of maize by using a newly developed resource, the RN-cM map. The RN-cM map charts the distribution of crossing over in the form of recombination nodules (RNs) along synaptonemal complexes (SCs, pachytene chromosomes) and allows genetic cM distances to be converted into physical micrometer distances on chromosomes. When this conversion is made, most of the EST markers used in the study are located distally on the chromosomes in euchromatin. ESTs are significantly clustered on chromosomes, even when only euchromatic chromosomal segments are considered. Gene density and recombination rate (as measured by EST and RN frequencies, respectively) are strongly correlated. However, crossover frequencies for telomeric intervals are much higher than was expected from their EST frequencies. For pachytene chromosomes, EST density is about fourfold higher in euchromatin compared with heterochromatin, while DNA density is 1.4 times higher in heterochromatin than in euchromatin. Based on DNA density values and the fraction of pachytene chromosome length that is euchromatic, we estimate that 1500 Mbp of the maize genome is in euchromatin. This overview of the organization of the maize genome will be useful in examining genome and chromosome evolution in plants.

³ Corresponding author.
E-mail lorinda.anderson{at}colostate.edu; fax (970) 491-0649.

[Supplemental material is available online at www.genome.org.]

CiteULike    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

				K. Fengler, S. M. Allen, B. Li, and A. Rafalski Distribution of Genes, Recombination, and Repetitive Elements in the Maize Genome Crop Sci., July 16, 2007; 47(S2): S-83 - S-95. [Abstract] [Full Text] [PDF]

				R. Bruggmann, A. K. Bharti, H. Gundlach, J. Lai, S. Young, A. C. Pontaroli, F. Wei, G. Haberer, G. Fuks, C. Du, et al. Uneven chromosome contraction and expansion in the maize genome Genome Res., October 1, 2006; 16(10): 1241 - 1251. [Abstract] [Full Text] [PDF]

				M. D. Yandeau-Nelson, B. J. Nikolau, and P. S. Schnable Effects of trans-acting Genetic Modifiers on Meiotic Recombination Across the a1-sh2 Interval of Maize Genetics, September 1, 2006; 174(1): 101 - 112. [Abstract] [Full Text] [PDF]

				C. J. Lawrence, T. E. Seigfried, H. W. Bass, and L. K. Anderson Predicting Chromosomal Locations of Genetically Mapped Loci in Maize Using the Morgan2McClintock Translator Genetics, March 1, 2006; 172(3): 2007 - 2009. [Abstract] [Full Text] [PDF]