Construction of physical maps for the sex-specific regions of papaya sex chromosomes

BMC Genomics

Research Article

Jiming Jiang¹  Wenli Zhang¹  Andrea R Gschwend²  Ray Ming²  Jan E Murray³  Jong-Kuk Na⁴  Jianping Wang⁵  Zdenek Kubat⁶  Cuixia Chen⁷  Paul H Moore⁸  Andrew H Paterson⁹  F Alex Feltus⁹  Rafael Navajas‒ Pérez^1,10  Qingyi Yu^1,11 

[1] Department of Horticulture, University of Wisconsin, 53706, Madison, WI, USA;Department of Plant Biology, University of Illinois at Urbana Champaign, 61801, Urbana, IL, USA;Department of Plant Biology, University of Illinois at Urbana Champaign, 61801, Urbana, IL, USA;Departamento de Genética, Facultad de Ciencias, Universidad de Granada, Granada Campus de Fuentenueva s/n, 18071, Spain;Department of Plant Biology, University of Illinois at Urbana Champaign, 61801, Urbana, IL, USA;Department of Agricultural Bio-resources, National Academy of Agricultural Science, RDA, 441-701, Suwon, Republic of Korea;Department of Plant Biology, University of Illinois at Urbana Champaign, 61801, Urbana, IL, USA;Department of Agronomy, University of Florida, 32610, Gainesville, FL, USA;Department of Plant Biology, University of Illinois at Urbana Champaign, 61801, Urbana, IL, USA;Laboratory of Plant Developmental Genetics, Institute of Biophysics, Academy of Sciences of the Czech Republic, Kralovopolska 135, CZ-612 65, Brno, Czech Republic;Department of Plant Biology, University of Illinois at Urbana Champaign, 61801, Urbana, IL, USA;Shandong Agricultural University, 271018, Tai’an, Shandong, China;Hawaii Agriculture Research Center, 96759, Kunia, HI, USA;Plant Genome Mapping Laboratory, University of Georgia, 30606, Athens, GA, USA;Plant Genome Mapping Laboratory, University of Georgia, 30606, Athens, GA, USA;Departamento de Genética, Facultad de Ciencias, Universidad de Granada, Granada Campus de Fuentenueva s/n, 18071, Spain;Texas AgriLife Research Center, 78596, Weslaco, TX, USA;

关键词: Bacterial artificial chromosome (BAC);    Carica papaya;    Sex chromosomes;    Sex determination;    Suppression of recombination;   

DOI  :  10.1186/1471-2164-13-176

 received in 2011-08-23, accepted in 2012-03-12,  发布年份 2012

来源: Springer

【 摘 要 】

BackgroundPapaya is a major fruit crop in tropical and subtropical regions worldwide. It is trioecious with three sex forms: male, female, and hermaphrodite. Sex determination is controlled by a pair of nascent sex chromosomes with two slightly different Y chromosomes, Y for male and Yh for hermaphrodite. The sex chromosome genotypes are XY (male), XYh (hermaphrodite), and XX (female). The papaya hermaphrodite-specific Yh chromosome region (HSY) is pericentromeric and heterochromatic. Physical mapping of HSY and its X counterpart is essential for sequencing these regions and uncovering the early events of sex chromosome evolution and to identify the sex determination genes for crop improvement.ResultsA reiterate chromosome walking strategy was applied to construct the two physical maps with three bacterial artificial chromosome (BAC) libraries. The HSY physical map consists of 68 overlapped BACs on the minimum tiling path, and covers all four HSY-specific Knobs. One gap remained in the region of Knob 1, the only knob structure shared between HSY and X, due to the lack of HSY-specific sequences. This gap was filled on the physical map of the HSY corresponding region in the X chromosome. The X physical map consists of 44 BACs on the minimum tiling path with one gap remaining in the middle, due to the nature of highly repetitive sequences. This gap was filled on the HSY physical map. The borders of the non-recombining HSY were defined genetically by fine mapping using 1460 F2 individuals. The genetically defined HSY spanned approximately 8.5 Mb, whereas its X counterpart extended about 5.4 Mb including a 900 Kb region containing the Knob 1 shared by the HSY and X. The 8.5 Mb HSY corresponds to 4.5 Mb of its X counterpart, showing 4 Mb (89%) DNA sequence expansion.ConclusionThe 89% increase of DNA sequence in HSY indicates rapid expansion of the Yh chromosome after genetic recombination was suppressed 2–3 million years ago. The genetically defined borders coincide with the common BACs on the minimum tiling paths of HSY and X. The minimum tiling paths of HSY and its X counterpart are being used for sequencing these X and Yh-specific regions.

【 授权许可】

Unknown   
© Na et al.; licensee BioMed Central Ltd. 2012. This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.