ARS | Publication request: Molecular characterization of the AP2-like Q gene homoeoallele on chromosome 5D in hexaploid wheat

Submitted to: Plant and Animal Genome VX Conference Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: October 15, 2006
Publication Date: January 14, 2007
Citation: Zhang, Z., Simons, K.J., Faris, J.D. 2007. Molecular characterization of the AP2-like Q gene homoeoallele on chromosome 5D in hexaploid wheat. Plant and Animal Genome VX Conference Abstracts. p. 300.

Technical Abstract: The Q gene of wheat is responsible for many morphological traits associated with domestication. Q is located on wheat chromosome 5A and it is a member of the AP2 class of transcription factors. Genotypes harboring the q allele on chromosome 5A have speltoid spikes, which include non free-threshing seed, tough glumes, and other primitive characteristics. Homoeoalleles of Q exist on chromosomes 5B and 5D, but their functions are unknown. Here, we initiated the structural and functional characterization of the 5D homoeoallele of the Q gene (5Dq). Evaluation of deletion mutants indicated that 5Dq also contributes to the suppression of speltoid characters, but to a lesser degree than does the Q allele on 5A. The genomic sequence of 5Dq is 3,254 bp and is alternately spliced producing two transcriptional variants in spike tissue. One variant resulted from the splicing of ten exons that corresponded to the splicing structure of 5AQ/q alleles, and encodes a predicted protein of 452 amino acids. The other variant lacked the splicing of the first intron, which resulted in a frameshift that led to a stop codon within the first AP2 domain. Sequence alignments of 5AQ and 5Dq indicated that they shared 90 and 94% identity at the nucleic acid and amino acid levels, respectively. RT-PCR experiments indicated that 5Dq is expressed in immature spikes. Characterization of the q homoeoalleles will provide insights regarding polyploid gene regulation of genetic networks associated with domestication and morphology.