Physical and genetic structure of the maize genome reflects its complex evolutionary history.
Maize (Zea mays L.) is one of the most important cereal crops and a model for the study of genetics, evolution, and domestication. To better understand maize genome organization and to build a framework for genome sequencing, we constructed a sequence-ready fingerprinted contig-based physical map that covers 93.5% of the genome, of which 86.1% is aligned to the genetic map. The fingerprinted contig map contains 25,908 genic markers that enabled us to align nearly 73% of the anchored maize genome to the rice genome. The distribution pattern of expressed sequence tags correlates to that of recombination. In collinear regions, 1 kb in rice corresponds to an average of 3.2 kb in maize, yet maize has a 6-fold genome size expansion. This can be explained by the fact that most rice regions correspond to two regions in maize as a result of its recent polyploid origin. Inversions account for the majority of chromosome structural variations during subsequent maize diploidization. We also find clear evidence of ancient genome duplication predating the divergence of the progenitors of maize and rice. Reconstructing the paleoethnobotany of the maize genome indicates that the progenitors of modern maize contained ten chromosomes.
Arizona Genomics Institute, University of Arizona, Tucson, Arizona, United States of America.
Fusheng
F
Wei
Ed
E
Coe
William
W
Nelson
Arvind K
AK
Bharti
Fred
F
Engler
Ed
E
Butler
HyeRan
H
Kim
Jose Luis
JL
Goicoechea
Mingsheng
M
Chen
Seunghee
S
Lee
Galina
G
Fuks
Hector
H
Sanchez-Villeda
Steven
S
Schroeder
Zhiwei
Z
Fang
Michael
M
McMullen
Georgia
G
Davis
John E
JE
Bowers
Andrew H
AH
Paterson
Mary
M
Schaeffer
Jack
J
Gardiner
Karen
K
Cone
Joachim
J
Messing
Carol
C
Soderlund
Rod A
RA
Wing
D002874:Chromosome Mapping; D022202:Chromosomes, Artificial, Bacterial / Q000235:genetics; D032461:Chromosomes, Plant / Q000235:genetics; D016172:DNA Fingerprinting; D018744:DNA, Plant / Q000235:genetics; D002523:Edible Grain / Q000235:genetics; D019143:Evolution, Molecular; D020440:Gene Duplication; D015321:Gene Rearrangement; D018745:Genome, Plant; D012275:Oryza / Q000235:genetics; D010802:Phylogeny; D013045:Species Specificity; D003313:Zea mays / Q000235:genetics*
D018744:DNA, Plant