Analysis of genetic diversity in early introduced clones of rubber tree (Hevea brasiliensis) using RAPD and microsatellite markers

Genetic analysis in 53 early introduced clones of rubber tree (Hevea brasiliensis) collected from different areas in Southern Thailand was performed using RAPD (Random Amplified Polymorphic DNA) and microsatellite markers. Seventeen cultivated clones (34 samples) were also included to compare DNA patterns. DNA was isolated from leaf samples using CTAB buffer. One hundred and ninety two 10-base oligonucleotide primers for RAPD were first screened and 8 primers (OPB-17, OPN-16, OPR-02, OPR-11, OPZ-04, OPAD-01, OPAD-10 and OPAD-12) were chosen for genetic variation analysis in 87 individual plants. Seventy amplification fragments were obtained from the 8 primers with an average of 8.75 fragments for each primer. From all fragments 55 were polymorphic fragments (78.57%). One RAPD primer (OPAD-01) yielded a 700-bp fragment that was present only in the Tjir1 clone. Four microsatellite primer pairs (hmac4, hmct1, hmct5 and hmac5) produced a total of 44 amplified fragments with an average of 14.67 fragments per primer, of which 37 were polymorphic (84.09%) while hmac5 produced only monomorphic fragments. A phenogram showing genetic similarities among rubber trees was constructed based on the polymorphic bands of the RAPD and microsatellite analyses using UPGMA (Unweighted Pair-Group Method Using Arithmetic Average). Cluster analysis was performed by the NTSYS Version 2.1 program. The results from phenogram showed that the 87 rubber clones could be clustered into 6 groups with similarity coefficients ranging from 0.541-1.000. Cultivated clones revealed more narrow genetic diversity compared to the early introduced clones. The clustering was not correlated with the geographical location of the collected samples.