Chromolaena odorata is a native of America and has become a noxious invader of the tropics and subtropics. Previous researches have been conducted on the genetic diversity of C. odorata, but some important questions remain unresolved. It is not clear whether low genetic diversity is a common feature of C. odorata across Asia where the species has a history of introduction of over 100 years. It is also uncertain as to whether hybridization occurred between genotypes from, presumably, different native sources of C. odorata during this long history of invasion in Asia. Finally, there remains a lack of clarity regarding the specific native locations and original genotypes of the species that were introduced to Asia.
Dr. LI Qiaoming of Xishuangbanna Tropical Botanical Garden (XTBG) and her colleagues used both maternally inherited chloroplast DNA (cpDNA) and biparentally inherited nuclear DNA (ITS and microsatellite loci) to investigate population genetic architecture and the phylogeographic haplotype network in C. odorata sampled across its range in Asia.
They aimed to determine whether C. odorata existed as a single invasive genotype in Asia, or as multiple lineages given the documented initiation of invasion from more than one site in Asia. They then attempted to trace the invasive routes and identify possible source locations of the invasion of C. odorata into Asia. They also discussed the possible mechanisms that might have promoted the successful invasion of C. odorata into Asia.
The presence of a single haplotype of cpDNA and ITS fragments, combined with one predominant multilocus genotype based on six microsatellite loci in samples spreading over a vast geographic area, indicated that C. odorata might exist as a single lineage in Asia. Their results suggested that the dominant genotype found in Asia was likely to be an invasive genotype that might be more invasive than others. Their results also suggested that it is likely that only one single introduction of C. odorata occurred in Asia, and that the most likely geographic origin of that introduction was Trinidad, Tobago and adjacent areas in the West Indies.
The Study entitled “Invasion genetics of Chromolaena odorata(Asteraceae): extremely low diversity across Asia” has been published online in Biological Invasions.
