Something Fishy about Siamese Fighting Fish (Betta splendens) Sex: Polygenic Sex Determination or a Newly Emerged Sex-Determining Region?

Thitipong Panthum; Kitipong Jaisamut; Worapong Singchat; Syed Farhan Ahmad; Lalida Kongkaew; Wongsathit Wongloet; Sahabhop Dokkaew; Ekaphan Kraichak; Narongrit Muangmai; Prateep Duengkae; Kornsorn Srikulnath

doi:10.3390/cells11111764

Something Fishy about Siamese Fighting Fish (Betta splendens) Sex: Polygenic Sex Determination or a Newly Emerged Sex-Determining Region?

Cells. 2022 May 27;11(11):1764. doi: 10.3390/cells11111764.

Authors

Thitipong Panthum^{1

2

3}, Kitipong Jaisamut^{1

3}, Worapong Singchat^{1

3}, Syed Farhan Ahmad^{1

3

4}, Lalida Kongkaew^{1

3}, Wongsathit Wongloet^{1

3}, Sahabhop Dokkaew⁵, Ekaphan Kraichak^{1

6}, Narongrit Muangmai^{1

7}, Prateep Duengkae^{1

3}, Kornsorn Srikulnath^{1

2

3

4

8

9

10

11}

Affiliations

¹ Animal Genomics and Bioresource Research Unit (AGB Research Unit), Faculty of Science, Kasetsart University, Bangkok 10900, Thailand.
² Interdisciplinary Graduate Program in Bioscience, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand.
³ Special Research Unit for Wildlife Genomics (SRUWG), Department of Forest Biology, Faculty of Forestry, Kasetsart University, Bangkok 10900, Thailand.
⁴ The International Undergraduate Program in Bioscience and Technology, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand.
⁵ Department of Aquaculture, Faculty of Fisheries, Kasetsart University, Bangkok 10900, Thailand.
⁶ Department of Botany, Kasetsart University, Bangkok 10900, Thailand.
⁷ Department of Fishery Biology, Faculty of Fisheries, Kasetsart University, Bangkok 10900, Thailand.
⁸ Laboratory of Animal Cytogenetics and Comparative Genomics (ACCG), Department of Genetics, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand.
⁹ Center for Advanced Studies in Tropical Natural Resources, National Research University-Kasetsart University, Kasetsart University, (CASTNAR, NRU-KU, Thailand), Bangkok 10900, Thailand.
¹⁰ Center of Excellence on Agricultural Biotechnology (AG-BIO/PERDO-CHE), Bangkok 10900, Thailand.
¹¹ Amphibian Research Center, Hiroshima University, Kagamiyama, Higashihiroshima 739-8527, Japan.

Abstract

Fishes provide a unique and intriguing model system for studying the genomic origin and evolutionary mechanisms underlying sex determination and high sex-chromosome turnover. In this study, the mode of sex determination was investigated in Siamese fighting fish, a species of commercial importance. Genome-wide SNP analyses were performed on 75 individuals (40 males and 35 females) across commercial populations to determine candidate sex-specific/sex-linked loci. In total, 73 male-specific loci were identified and mapped to a 5.6 kb region on chromosome 9, suggesting a putative male-determining region (pMDR) containing localized dmrt1 and znrf3 functional sex developmental genes. Repeat annotations of the pMDR revealed an abundance of transposable elements, particularly Ty3/Gypsy and novel repeats. Remarkably, two out of the 73 male-specific loci were located on chromosomes 7 and 19, implying the existence of polygenic sex determination. Besides male-specific loci, five female-specific loci on chromosome 9 were also observed in certain populations, indicating the possibility of a female-determining region and the polygenic nature of sex determination. An alternative explanation is that male-specific loci derived from other chromosomes or female-specific loci in Siamese fighting fish recently emerged as new sex-determining loci during domestication and repeated hybridization.

Keywords: Betta splendens; DArTseq™; SNP; betta; sex determination.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Animals
Female
Fishes* / genetics
Genome / genetics
Genomics
Male
Sex Chromosomes / genetics
Sex Determination Analysis*

Grants and funding

This research was financially supported in part by the High-Quality Research Graduate Development Cooperation Project between Kasetsart University and the National Science and Technology Development Agency (NSTDA) awarded to K.S. and (6417400247) T.P.; the Thailand Science Research and Innovation through The Kasetsart University Reinventing University Program 2021 (3/2564) awarded to K.S. and T.P.; the e-ASIA Joint Research Program (no. P1851131) awarded to K.S. and W.S.; a grant from the National Science and Technology Development Agency (NSTDA) (NSTDA P-19-52238 and JRA-CO-2564-14003-TH) awarded to K.S. and W.S.; a postdoctoral researcher award at Kasetsart University awarded to S.F.A. and K.S. and the Office of the Ministry of Higher Education, Science, Research and Innovation. No funding source was involved in the study design, collection, analysis and interpretation of the data, writing the report, or the decision to submit the article for publication.