Genetic diversity of alligator weed in China by RAPD analysis

Abstract

Random amplified polymorphic DNA (RAPD) was applied to analyze geneticdiversity of an invasive weedy species, alligator weed (Alternantheraphiloxeroides (Martius) Grisebach), collected from eight differentsites in southern China. Amplified by 108 RAPD primers, 391 bands wereidentified from samples collected from three of the eight sites withconsiderably large spatial intervals, but no genetic variation was detectedamong the samples. A total number of 196 RAPD fragments were amplified from allsamples collected in the eight sites by 31 primers that produced the mostconsistent results, but no genetic variation was detected within or betweenpopulations. The molecular data indicated extremely low genetic diversity in thealligator weed. Given the fact that the alligator weed is a serious invasiveweed, and widely found in China, we consider that the low genetic diversity ofthe alligator weed does not affect the success of its expansion in China, andlow genetic diversity does not necessarily lead to endangered status of a plantspecies. In addition, molecular evidence from this study suggests that thealligator weed in southern China might originate from a very few clones or evenonly from a single clone. Therefore, the rapid range expansion of the alligatorweed is most likely the result of a massive vegetative propagation since it wasintroduced in China.