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SUMMARY:Unraveling a Transcriptional Network Involved in Maize Domesticati
 on - John Doebley\,  University of Wisconsin-Madison
DTSTART:20120315T160000Z
DTEND:20120315T170000Z
UID:TALK31565@talks.cam.ac.uk
CONTACT:Jill Harrison
DESCRIPTION:Maize is a domesticated form of a wild Mexican grass called te
 osinte.  The domestication of maize from teosinte occurred about 9\,000 ye
 ars ago.  As a result of human (artificial) selection during the domestica
 tion process\, dramatic changes in morphology arose such that maize no lon
 ger closely resembles its teosinte ancestor in ear and plant architecture.
  We have identified and analyzed three of the genes involved in these morp
 hological changes. First\, teosinte branched (tb1) is largely responsible 
 for the difference between the long branches of teosinte versus the short 
 branches of maize.  tb1 encodes a transcriptional regulator that functions
  as a repressor of branch elongation. Gene expression analysis indicates t
 hat the product of the teosinte allele of tb1 accumulates at about half th
 e level of the maize allele.  Fine-mapping experiments show that the diffe
 rences in phenotype and gene expression are controlled in part by an upstr
 eam transposon insertion that acts as an enhancer of gene expression. Seco
 nd\, teosinte glume architecture (tga1) is largely responsible for the for
 mation of a casing that surrounds teosinte seeds but is lacking in maize. 
  tga1 also encodes a transcriptional regulator\, however in this case a si
 ngle amino acid change represents the functional difference between maize 
 and teosinte.  This single amino acid change appears to convert the maize 
 allele into a transcriptional repressor of target genes. Third\, grassy ti
 llers (gt1) contributes to differences in plant architecture and encodes a
 n HD-ZIP transcription factor. Causative changes at gt1 appear to be compl
 ex\, involving multiple changes. tb1\, tga1 and gt1 are members of the sam
 e developmental network which regulates shade avoidance. This pathway was 
 a target of human selection during the domestication process.    
LOCATION:Department of Plant Sciences\, Large Lecture Theatre
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