Maternal mismatches in farmed tilapia strains (Oreochromis spp.) in the Philippines as revealed by mitochondrial COI gene

Abstract

The introduction of genetically enhanced tilapia has significantly boosted the performance of Philippine aquaculture industry. While enhanced strains contribute to the increase in tilapia production, genetic characterization of present tilapia stocks is critical to maintain their quality and to ensure the genetic gains are sustained. To understand and determine the genetic relationship of the genetically enhanced strains produced in the Philippines, mitochondrial cytochrome oxidase subunit I (COI) gene using DNA barcoding approach was analyzed. Specimens representing 10 genetically enhanced strains (GIFT, FaST, GET-EXCEL, GST, SST, COLD, YY-male, GMT, Molobicus, and BEST), three red tilapia (Taiwan red, Florida red, and FAC-red), and two pure lines (initially identified as O. aureus and O. spilurus) were collected, sequenced, and identified using DNA barcoding. Results revealed that farmed tilapias consisted of four different Oreochromis species. As expected, COI could not distinguish individuals at the strain level but surprisingly, mismatch between the species of maternal origin and present-day offspring was observed. This particular result may pose a question on the genetic purity and integrity of the strains being distributed to farmers and suggests a re-evaluation of the effectiveness of major tilapia breeding centers in maintaining their stocks.

Keywords:

• Aquaculture
• breeding
• cytochrome oxidase subunit 1
• DNA barcoding
• tilapia

Acknowledgements

The authors express their utmost gratitude to the National Fisheries Research and Development Institute (NFRDI) and GFL-LABRATS, especially to JK Lacsamana, Ivane Pedrosa-Gerasmio and Angelli Asis-Egar who helped in the collection and processing of samples. The authors also like to thank the following people for providing assistance during the sample collection: Ma. Theresa Oclos-Tarampi and Jodecyl Danting of NFFTC; Joni Resultay and Dr. Westly Rosario of NIFTDC; Jovy Ann Valera and Dr. Rowena Romana-Eguia of SEAFDEC-AQD, Binangonan Station and the technical staff of BFAR-ROS, Compostella Valley.

Disclosure statement

The authors report that they have no conflicts of interest. The authors alone are responsible for the content and writing of this article.

Funding statement

This work was supported by a Department of Agriculture –Biotech Program grant BIOTECH-R1305.