Independent Domestication of Two Old World Cotton Species.
Domesticated cotton species provide raw material for the majority of the world's textile industry. Two independent domestication events have been identified in allopolyploid cotton, one in Upland cotton (Gossypium hirsutum L.) and the other to Egyptian cotton (Gossypium barbadense L.). However, two diploid cotton species, Gossypium arboreum L. and Gossypium herbaceum L., have been cultivated for several millennia, but their status as independent domesticates has long been in question. Using genome resequencing data, we estimated the global abundance of various repetitive DNAs. We demonstrate that, despite negligible divergence in genome size, the two domesticated diploid cotton species contain different, but compensatory, repeat content and have thus experienced cryptic alterations in repeat abundance despite equivalence in genome size. Evidence of independent origin is bolstered by estimates of divergence times based on molecular evolutionary analysis of f7,000 orthologous genes, for which synonymous substitution rates suggest that G. arboreum and G. herbaceum last shared a common ancestor approximately 0.4-2.5 Ma. These data are incompatible with a shared domestication history during the emergence of agriculture and lead to the conclusion that G. arboreum and G. herbaceum were each domesticated independently.
Department of Ecology, Evolution and Organismal Biology, Iowa State University DuPont Pioneer, Johnston, IA.
Simon
S
Renny-Byfield
Plant and Wildlife Science Department, Brigham Young University.
Justin T
JT
Page
Plant and Wildlife Science Department, Brigham Young University.
Joshua A
JA
Udall
Institute for Genomics, Biocomputing and Biotechnology, Mississippi State University Department of Computer Science and Engineering, Mississippi State University.
William S
WS
Sanders
Institute for Genomics, Biocomputing and Biotechnology, Mississippi State University Department of Plant and Soil Sciences, Mississippi State University.
Daniel G
DG
Peterson
Institute for Genomics, Biocomputing and Biotechnology, Mississippi State University.
Mark A
MA
Arick
Department of Ecology, Evolution and Organismal Biology, Iowa State University.
Corrinne E
CE
Grover
Department of Ecology, Evolution and Organismal Biology, Iowa State University jfw@iastate.edu.
Jonathan F
JF
Wendel
D004171:Diploidy; D000071278:Domestication; D019143:Evolution, Molecular; D018745:Genome, Plant; D003368:Gossypium / Q000235:genetics*; D059014:High-Throughput Nucleotide Sequencing; D010802:Phylogeny; D011123:Polyploidy; D017422:Sequence Analysis, DNA
Gossypium; crop plants; genome size; molecular evolution; repetitive DNA