Molecular differentiation of two morphological variants of Gracilariasalicornia

摘要

Xia in 1986 combined Gracilaria salicornia, G. canaliculata (G. crassa), G. cacalia and G. minor into one species: G. salicornia. Two morphological variants of G. salicornia were collected from different localities in Malaysia. Variant A collected from Morib, Selangor grew on the roots of Avicennia. The samples showed absence of main axis; segmented constrictions throughout; cylindrical or slightly compressed thalli. Variant B was collected from the mudflats of Tanjung Tuan, growing on rocks, coral or forming mats on the mud. Plants showed absence of main axis; segments were not constricted throughout the plant (if present only slightly articulated at the upper part), branching was dichotomous or irregular; cylindrical or slightly compressed thalli. The technique of Random Amplified Polymorphic DNA analysis (RAPD) was used to investigate molecular characteristics of the two variants. Out of sixty Operon primers that were screened, four primers, OPA 1, OPA 10, OPA 11 and OPK 7 were able to give polymorphism. The fingerprints generated were stable and reproducible on repeated analysis. The DNA fingerprints generated were visually analysed and clustering analysis was carried out using GelCompar 4.0. The matrix of similarities was based on the Dice coefficients (S-D) and the cluster analysis was carried out using the unweighted pair group method using arithmetic averages (UPGMA). DNA analysis showed that two primers (OPA 01, CAGGCCCTTC and OPK 07, AGCGAGCAAG) were able to differentiate the two variants.