Genetic Diversity of Siamese Gourami from Sumatra, Java and Kalimantan for Selective Breeding of Fish Culture

Abstract

Siamese gourami (Trichogaster pectoralis) is a species of fish that was introduced from Thailand to Indonesia in 1934. Siamese gourami farming activities during the period 2008-2011 ranged between 2.82-12.36% of total aquaculture production annually. Meanwhile, Siamese gourami fishing activities has led to overfishing and environmental degradation that could threaten its sustainability. The development of fish farming should be done for Siamese gourami supported by the efforts of domestication. Population genetics database of Siamese gourami from natural and domesticated populations stocks are necessary to be evaluated for its genetic structure and potential based on genotype fitness potential, selection, genetic drift, and population genetic diversity genotypes and phenotypes characteristics of intra and interpopulation are very important informations as references for sustainable management of genetic resources in aquaculture activities and selective breeding efforts through selection and crossbreeding. The purpose of this study is to identify the genotypes and phenotypes diversity of 9 Siamese gourami populations from Sumatra, Java and Kalimantan island based on Random Amplified Polymorphism DNA (RAPD) and truss morphometric analysis. The significancy of this research was to provide the population genetics database of Siamese gourami for selection and development of fish farming and breeding strategies on Siamese gourami culture. Fish samples of Siamese gourami analysed were originating from the island of Sumatra (Jambi, Palembang, Lampung), Java (West Java, Central Java, East Java), and Kalimantan (West Kalimantan, Central Kalimantan and South Kalimantan). Thirty samples of each population were used for truss morphometric analysis and 10 samples of fin specimen for RAPD analysis. DNA extraction was conducted using Phenol-Chloroform, while the primers of DNA amplification consisted of OPC 01-20 and 01-20 OPA. The DNA amplification process was held by polymerize chain reaction (PCR) using the reaction composition of a total volume of 25 mL: DNA 2 mL, 2 mL with a concentration of 10 pmol primer, 12.5 mL KAPA2G Robust HotStart Ready Mix, and 21 mL H2O. The characterization of truss morphometric were measured using with reference the theory of Blezinsky and Doyle method (1987). Water quality parameters in fish sampling locations included temperature, pH and dissolved oxygen.Three Siamese gourami populations showed genetic diversity above 50% which were as natural population collected from East Java (65.62%), Lampung (59.37%) and Palembang (56.25%). While two populations that had lower genetic diversity were collected from West Java (31.25%) and West Kalimantan (21.87%). As domestication population, the population showed a relatively low genetic diversity, these were from Central Java (12.5%) and Jambi (6.25%). Similarly with the population from Central Kalimantan (9.37%) and South Kalimantan (6.25%) that were from nature population. Based on genetic distance dendrogram of nine Siamese gourami populations from Sumatra, Java, and Kalimantan illustrated that the populations from West Java and South Kalimantan is the most distant, while three populations from East Java, Lampung and Palembang formed a different group with six other populations. By morphometric characteristics, the coefficient of variance 16 truss morphometric characters ranged between 2.92-12.99%, and the similarity index of intrapopulation was generally below to 50% except the population from Central Java showed high uniformity index (73.3%) and population from West Kalimantan (66.7%). Based on the genotypic and phenotypic characteristics of nine Siamese gourami populations from Sumatra, Java, and Kalimantan, these could be concluded that Siamese gourami populations from East Java, Palembang and Lampung potential as genetic resource for sustainable breeding cultivation. The development of genetic resources of Siamese gourami is probably through hybridization between populations, for example doing merger of about two or more populations from nature having different genetic diversity or introduction of nature populations into farming populations to increase genetic diversity of cultivated population.