The genetic diversity of nine populations of Lemna, seven for Lemna gibba and two for L. minor was evaluated. The populations were collected from different water courses in the Nile Delta, Egypt; agricultural drainage, mixed (agricultural and industrial) drainage and irrigation canals. The genetic relationship among the examined populations was estimated based on recorded differences in SDS-PAGE profiles, five isozyme systems and ISSR fingerprinting. Construction of distance trees illustrating the genetic distance among the studied populations was performed using the UPGMA method. The results revealed a high level of inter and intra-species level of genetic diversity. The two species were delimited as two clusters at a distance of 1.52 in a UPGMA tree and Limna gibba populations were separated into two subclusters at a distance of 1.20 reflecting the samples collected from Kafr El-Sheikh were separated from those collected from Gharbia. Geographical distributions of the samples appear to have obvious influence on the genetic diversity of the studied populations.
Genetic diversity; ISSR; isozyme; SDS-PAGE; Lemnaceae