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Fine mapping of shattering locus Br2 reveals a putative chromosomal inversion polymorphism between the two lineages of Aegilops tauschii.
Theor Appl Genet. 2015 Apr; 128(4):745-55.TA

Abstract

KEY MESSAGE

This work laid the foundation for cloning of shattering gene Br2 and provided first line of evidence that two major Aegilops tauschii lineages are differentiated by an inversion polymorphism. Chromosome inversions often accompany population differentiation and capture local adaptation during speciation. Aegilops tauschii, the D-genome donor species of hexaploid wheat, consists of two genetically isolated lineages, L1 and L2, but little is known about the genetic mechanisms underlying the population differentiation in this diploid species. During fine mapping of the shattering gene Br2 using a large F2 population derived from a cross between TA1604 (an L1 accession) and AL8/78 (an L2 accession), we found contrasting patterns of crossover distribution in the Br2 interval and neighboring regions despite the high local gene synteny with Brachypodium distachyon and rice. Br2 was localized in a 0.08-cM interval, and 13 marker loci formed a block, where single-crossovers were completely suppressed, but double-crossovers were enriched with a recombination rate of ~11 cM/Mb. In contrast, in a neighboring region no double-crossover was recovered, but single-crossover rate reached 24 cM/Mb, which is much higher than the genome-wide average. This result suggests a putative inversion polymorphism between the parental lines in the Br2 region. Genotyping using the markers from the Br2 region divided a collection of 55 randomly sampled A. tauschii accessions into two major groups, and they are largely genetically isolated. The two groups correspond to the L1 and L2 lineages based on their geographic distribution patterns. This provides first evidence that inversions may underlie the evolution of A. tauschii lineages. The presence of inter-lineage inversions may complicate map-based cloning in A. tauschii and transfer of useful traits to wheat.

Authors+Show Affiliations

Department of Biology and Microbiology, South Dakota State University, Brookings, SD, 57007, USA.No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, U.S. Gov't, Non-P.H.S.

Language

eng

PubMed ID

25656150

Citation

Zhang, Zhengzhi, et al. "Fine Mapping of Shattering Locus Br2 Reveals a Putative Chromosomal Inversion Polymorphism Between the Two Lineages of Aegilops Tauschii." TAG. Theoretical and Applied Genetics. Theoretische Und Angewandte Genetik, vol. 128, no. 4, 2015, pp. 745-55.
Zhang Z, Zhu H, Gill BS, et al. Fine mapping of shattering locus Br2 reveals a putative chromosomal inversion polymorphism between the two lineages of Aegilops tauschii. Theor Appl Genet. 2015;128(4):745-55.
Zhang, Z., Zhu, H., Gill, B. S., & Li, W. (2015). Fine mapping of shattering locus Br2 reveals a putative chromosomal inversion polymorphism between the two lineages of Aegilops tauschii. TAG. Theoretical and Applied Genetics. Theoretische Und Angewandte Genetik, 128(4), 745-55. https://doi.org/10.1007/s00122-015-2469-1
Zhang Z, et al. Fine Mapping of Shattering Locus Br2 Reveals a Putative Chromosomal Inversion Polymorphism Between the Two Lineages of Aegilops Tauschii. Theor Appl Genet. 2015;128(4):745-55. PubMed PMID: 25656150.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Fine mapping of shattering locus Br2 reveals a putative chromosomal inversion polymorphism between the two lineages of Aegilops tauschii. AU - Zhang,Zhengzhi, AU - Zhu,Huilan, AU - Gill,Bikram S, AU - Li,Wanlong, Y1 - 2015/02/06/ PY - 2014/08/04/received PY - 2015/01/26/accepted PY - 2015/2/7/entrez PY - 2015/2/7/pubmed PY - 2015/5/20/medline SP - 745 EP - 55 JF - TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik JO - Theor Appl Genet VL - 128 IS - 4 N2 - KEY MESSAGE: This work laid the foundation for cloning of shattering gene Br2 and provided first line of evidence that two major Aegilops tauschii lineages are differentiated by an inversion polymorphism. Chromosome inversions often accompany population differentiation and capture local adaptation during speciation. Aegilops tauschii, the D-genome donor species of hexaploid wheat, consists of two genetically isolated lineages, L1 and L2, but little is known about the genetic mechanisms underlying the population differentiation in this diploid species. During fine mapping of the shattering gene Br2 using a large F2 population derived from a cross between TA1604 (an L1 accession) and AL8/78 (an L2 accession), we found contrasting patterns of crossover distribution in the Br2 interval and neighboring regions despite the high local gene synteny with Brachypodium distachyon and rice. Br2 was localized in a 0.08-cM interval, and 13 marker loci formed a block, where single-crossovers were completely suppressed, but double-crossovers were enriched with a recombination rate of ~11 cM/Mb. In contrast, in a neighboring region no double-crossover was recovered, but single-crossover rate reached 24 cM/Mb, which is much higher than the genome-wide average. This result suggests a putative inversion polymorphism between the parental lines in the Br2 region. Genotyping using the markers from the Br2 region divided a collection of 55 randomly sampled A. tauschii accessions into two major groups, and they are largely genetically isolated. The two groups correspond to the L1 and L2 lineages based on their geographic distribution patterns. This provides first evidence that inversions may underlie the evolution of A. tauschii lineages. The presence of inter-lineage inversions may complicate map-based cloning in A. tauschii and transfer of useful traits to wheat. SN - 1432-2242 UR - https://www.unboundmedicine.com/medline/citation/25656150/Fine_mapping_of_shattering_locus_Br2_reveals_a_putative_chromosomal_inversion_polymorphism_between_the_two_lineages_of_Aegilops_tauschii_ L2 - https://dx.doi.org/10.1007/s00122-015-2469-1 DB - PRIME DP - Unbound Medicine ER -