RAPD-PCR was performed using six random primers to identify the genetic diversity among six plant samples belong to two genera (Euphorbia and
Ricinus). The dendrogram, based on genetic distance, depict the relationship
among the investigated plant samples, separate clearly the six samples. The closest relationship was observed between E. geniculata and E. aphylla; and E. pulcherrima and E. peplus, while this relationship was quite separated between these
four samples and the other two samples E. cactus and R. communis. Fragments
generated by the six primers show a polymorphism ratio of 88.9%. Bands 3500
and 750 bp generated by primer OP-Z13, and also bands 2000, 1500, 1400, 1200,
1000, 720 and 550 bp generated by primer OP-A09 existing only in the plant
samples of E. geniculata and E. aphylla, which suggest that these bands can be
used as a positive molecular marker to identify these plant samples. Bands 2500,
1720, 1650, 1300, 950 and 250 bp generated by primer OP-A09, and band 1200
bp generated by primer OP-A20 and band 350 bp generated by primer OP-Z19
and band 250 bp generated by primer OP-Z17 were common in all plant samples
of family Euphorbiaceae. Moreover, band 430 bp generated by primer OP-Z17
was characterized for Ricinus communis and absent in other plants of genus Euphorbia. Also, band 2700 bp generated by primer OP-A20 and band 210 bp generated by primer OP-Z19 existing only in Euphorbia peplus. This study highlights the usefulness of RAPD assay for determining genetic variation in different
plant genera and for estimating genetic distances between different plant samples. Moreover, knowledge of genetic distance among genera and species, and
genetic diversity/structure within genera could be useful for conservation of genetic resources. Data presented here are the first report in Egypt of genetic variation inside genera Euphorbia and Ricinus described at the molecular level. We
consider this work as a first step in molecular characterization of genera Euphorbia and Ricinus, thus, it is recommended to extend the panel of samples and
primers in the future.