Delimitation of wheat ph1b deletion and development of ph1b-specific DNA markers
We detected the deletion breakpoints of wheat ph1b mutant and the actual size of the deletion. Also, we developed ph1b deletion-specific markers useful for ph1b-mediated gene introgression and genome studies.
The Ph1 (pairing homoeologous) locus has been considered a major genetic system for the diploidized meiotic behavior of the allopolyploid genome in wheat. It functions as a defense system against meiotic homoeologous pairing and recombination in polyploid wheat. A large deletion of the genomic region harboring Ph1 on the long arm of chromosome 5B (5BL) led to the ph1b mutant in hexaploid wheat ‘Chinese Spring,’ which has been widely used to induce meiotic homoeologous recombination for gene introgression from wild grasses into wheat. However, the breakpoints and physical size of the deletion remain undetermined. In the present study, we first anchored the ph1b deletion on 5BL by the high-throughput wheat 90K SNP assay and then delimited the deletion to a genomic region of 60,014,523 bp by chromosome walking. DNA marker and sequence analyses detected the nucleotide positions of the distal and proximal breakpoints (DB and PB) of the ph1b deletion and the deletion junction as well. This will facilitate understanding of the genomic region harboring the Ph1 locus in wheat. In addition, we developed user-friendly DNA markers specific for the ph1b deletion. These new ph1b deletion-specific markers will dramatically improve the efficacy of the ph1b mutant in the meiotic homoeologous recombination-based gene introgression and genome studies in wheat and its relatives.
We thank members of the laboratories involved for their help to this research and Dr. Lili Qi for her critical review of the manuscript. This project is supported by Agriculture and Food Research Initiative Competitive Grant No. 2016-67014-24455 from the USDA National Institute of Food and Agriculture.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
- Giorgi B (1978) A homoeologous pairing mutant isolated in Triticum durum cv ‘Cappelli’. Mutat Breed Newsl 11:4–5Google Scholar
- Mello-Sampayo T, Canas AP (1973) Suppressors of meiotic chromosome pairing in common wheat. In: Sears ER, Sears LMS (eds) Proceedings of 4th international wheat genetics symposium, Univ. Missouri, Columbia, Missouri, August 6–11, pp 709–713Google Scholar
- Mello-Sampayo T, Lorente R (1968) The role of chromosome 3D in the regulation of meiotic pairing in hexaploid wheat. EWAC Newsl 2:16–24Google Scholar
- Morris R, Sears ER (1967) The cytogenetics of wheat and its relatives. In: Quisenberry KS, Reitz LP (eds) Wheat and wheat improvement, pp 19–87Google Scholar
- Sears ER (1952) Homoeologous chromosomes in Triticum aestivum. Genetics 37:624–631Google Scholar
- Upadhya MD, Swaminathan MS (1967) Mechanism regulating chromosome pairing in Triticum. Biol Zentralbl Suppl 86:239–255Google Scholar
- Zhang W, Zhang M, Zhu X, Chao S, Xu SS, Cai X (2015) Homoeologous pairing and molecular genotyping reveal new evolutionary evidence of wheat B genome (poster). Plant & Animal Genome XXIII, San Diego, CA, January 10–14, 2015Google Scholar
- Zhu X, Zhang W, Zhang M, Chao WS, Somo M, Ma GJ, Xu SS, Cai X (2014) Homoeologous recombination-based gene introgression and genome mapping in wheat (poster). Plant & Animal Genome XXII, San Diego, CA, January 11–15, 2014Google Scholar