ARS | Publication request: A Point Mutation Demonstrating the Pleiotropic Effects of the Domestication Gene Q in Hexaploid Wheat

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: October 8, 2008
Publication Date: January 14, 2008
Citation: Zhang, Z., Gill, B.S., Faris, J.D. 2008. A Point Mutation Demonstrating the Pleiotropic Effects of the Domestication Gene Q in Hexaploid Wheat. Plant and Animal Genome Conference XVII, p. 686

Technical Abstract: The Q gene is a major domestication gene in wheat because it confers the free-threshing character and pleiotropically influences many other crop-related agronomic traits. Q is a member of the APETALA2 (AP2) family of transcription factors. Here, we created a Q-disrupted mutant in the Triticum aestivum cv. Bobwhite (BW) to evaluate the function and pleiotropic effects of Q. Sequence analysis of the mutant revealed a point mutation within the first AP2 domain of the coding region. The level of transcription in the mutant (q) was significantly reduced compared to the wild type (Q). Consistent with previous reports, the comparison of wild type BW and the mutant indicated that Q influences plant height, spike emergence time, spike shape, rachis disarticulation, glume toughness, and threshability. However, in addition, the Q-disrupted mutant had fewer tillers and spikelets leading to reduced yield as compared to wild type BW. Cell morphology observations of the rachis and glumes revealed major differences in cell shape, arrangement and density, and abscission zone formation between the mutant and the wild type, which explained the underlying biological differences in glume architecture and threshability. Although mutations at brittle rachis (Br) and tough glume (Tg) genes led to first domestication of wheat, it was still a wild type crop plant. Our data show that it was the mutation that gave rise to the Q gene that contributed to modern plant type including square spike, increased yield and agronomic performance further substantiating Q as a “super” gene which nurtured the rise of modern human civilization.