ARS | Publication request: A Floral Homeotic Gene Key to the Domestication of Wheat.

Submitted to: Plant and Animal Genome VX Conference Abstracts
Publication Type: Abstract
Publication Acceptance Date: October 3, 2004
Publication Date: January 10, 2005
Citation: Faris, J.D., Simons, K.J., Fellers, J.P., Trick, H.N., Gill, B.S. 2005. A floral homeotic gene key to the domestication of wheat. Plant and Animal Genome Abstracts. p. 186.

Technical Abstract: The conversion of wild grasses into domesticated forms launched an agricultural revolution and the dawn of modern human civilization. In wheat, the Q gene is primarily responsible for domestication by governing traits that allow wheat to be harvested and threshed efficiently. Using a positional cloning approach, we isolated Q and found it to be a floral homeotic gene with similarity to the AP2 class of transcription factors. Ectopic expression analysis allowed us to observe both silencing and overexpression effects of Q. Transgenic plants exhibiting silencing of the transgene and endogenous Q genes mimicked the q phenotype. These plants were tall with long spikes, had fragile rachises and keeled tenacious glumes, and were not free-threshing. Transgenic plants expressing multiple copies of the transgene were short with compact heads, had tough rachises and round soft glumes, and were free-threshing. The number of expressed copies of the Q transgene was directly correlated with the degree of head compactness and plant height. These experiments also verified the pleiotropic influence that Q has on multiple domestication-related traits. Finally, comparative sequence analysis of the gene from five free-threshing (Q) species and seven non free-threshing (q) species, and orthologous sequences from maize, rice, and barley indicated that Q arose from a more primitive allele (q) through mutation.