MOLECULAR IDENTIFICATION OF THE FOUR SPECIES OF THE GENUS PELTEOBAGRUS AND THE GENETIC ANALYSIS OF THEIR HYBRID

The genus Pelteobagrus is classified in Order Siluriformer, Family Siluridae, consisting of 4 species: P. fulvidraco, P.vachelli, P. nitidus and P. eupogon. They are similar in morphological characters,which are easily influenced by the geograph-ical regions and environments. Therefore, it is often difficult to identify them accurately at morphological level. It is necessary toresearch the genetic difference and identify them more distinctly.RAPD(Random Amplification of Polymorphic DNA) technique,as an important tool for genetic study, is widely used in identification of species. 20 random primers(S1-S20) were used to studythe RAPD patterns of 4 species of genus Pelteobagrus, 6(S1, S2, S5, S7, S8, S17) among which could be employed to identify the4 species.Each species bore a unique band with the primer S7 used to RAPD amplification, while the others did not. We alsostudied the phylogenet ic relationships of this 4 species based on the data obtained from RAPD analysis above, and found that thegenetic distance fluctuated at the point of 015000. The genetic distance values of P. fulvidraco and P. eupogon, P. vachelli andP. nitidus were the least, 014816 and 014017 respectively. The phylogenetic tree showed that P. fulvidraco and P. eupogon originatedfrom a common branch,while P. vachelli and P. nitidus from another one. That indicated that they were closer in relationship.To study difference between the RAPD patterns of parents and that of offspring, in addition, individuals of P. fulvidraco(a)and P. vachelli were hybridized, and a group of F1 offsprings were generated. We investigated the offspings by RAPD methodand found three types of genetic patterns: full overlapping, overlapping-variation and overlapping-faintness. This indicated theDNA polymorphism of F1 offspings was increased,which forecasted the possiblility of heterosis.