Differentiation of two Pangasius species, Pangasius krempfi and Pangasius mekongensis using inter-simple sequence repeat markers

Abstract

Pangasius krempfi and Pangasius mekongensis belong to Pangasiidae family,which are widely distributed along the Mekong River and spend most of their life stages in the Mekong Delta. Compared to P. mekongensis, P. krempfi has higher economic value and has been cultured in recent years. However, these species can be misidentified because they are difficult to be dishtinguished at young stages (<10 grams) by morphological methods. Presently, applications of DNA markers are common in fish species identification with high efficiency and accuracy. This study applied Inter-sequence simple repeat (ISSR) to identify these two species based on species-specific bands. Samples were collected in Cu Lao Dung, Soc Trang province (11 samples/ species). DNA extracts from fish fins were amplified using primers screened from previous studies. PCR components and thermal cycles were optimized and adjusted depending on primers. Six primers with clear and species- specific were selected to analyze 11 samples/ species. Totally, 62 bands were detected ranging in size from 500 bp (ChiuSSR1, Micro11) to 2400 bp (ChiuSSR2) with 31 and 22 speciesspecific bands in P. mekongensis and P. krempfi, respectively. Nei’s genetic distance between P. krempfi and P. mekongensis was high at 74.2%, while their genetic identity was 25.8%. The results of this study provided a simple and quick tool for dentification of these two species, which is useful for aquaculture and future studies.