The evolution of apical dominance in maize.
The domestication of crop plants has often involved an increase in apical dominance (the concentration of resources in the main stem of the plant and a corresponding suppression of axillary branches). A striking example of this phenomenon is seen in maize (Zea mays spp. mays), which exhibits a profound increase in apical dominance compared with its probable wild ancestor, teosinte (Zea mays ssp. parviglumis). Previous research has identified the teosinte branched1 (tb1) gene as a major contributor to this evolutionary change in maize. We have cloned tb1 by transposon tagging and show here that it encodes a protein with homology to the cycloidea gene of snapdragon. The pattern of tb1 expression and the morphology of tb1 mutant plants suggest that tb1 acts both to repress the growth of axillary organs and to enable the formation of female inflorescences. The maize allele of tb1 is expressed at twice the level of the teosinte allele, suggesting that gene regulatory changes underlie the evolutionary divergence of maize from teosinte.
Doebley
J
J
Department of Plant Biology, University of Minnesota, St Paul 55108, USA. jdoebley@maroon.tc.umn.edu
Stec
A
A
Hubbard
L
L
D000483:Alleles; D000595:Amino Acid Sequence; D001483:Base Sequence; D005075:Biological Evolution; D003001:Cloning, Molecular; D004251:DNA Transposable Elements; D018744:DNA, Plant; D019143:Evolution, Molecular; D017343:Genes, Plant; D008969:Molecular Sequence Data; D009154:Mutation; D010940:Plant Proteins / Q000235:genetics*; D006109:Poaceae / Q000235:genetics; D015183:Restriction Mapping; D003313:Zea mays / Q000235:genetics* / Q000254:growth & development
D004251:DNA Transposable Elements; D018744:DNA, Plant; D010940:Plant Proteins; C105292:TB1 protein, Zea mays