A first step in understanding an invasive weed through its genes: an EST analysis of invasive Centaurea maculosa

As an initial step towards understanding the molecular mechanisms by which plants become invasive, we have generated a normalized Expressed Sequence Tag (EST) library comprising seven invasive populations of Centaurea maculosa, an invasive aster in North America. Seventy-seven percent of the 4423 unique transcripts showed significant similarity to existing proteins in the NCBI database and could be grouped based on gene ontology assignments.The C. maculosa EST library represents an initial step towards looking at gene-specific expression in this species, and will pave the way for creation of other resources such as microarray chips that can help provide a view of global gene expression in invasive C. maculosa and its native counterparts. To our knowledge, this is the first published set of ESTs derived from an invasive weed that will be targeted to study invasive behavior. Understanding the genetic basis of evolution for increased invasiveness in exotic plants is critical to understanding the mechanisms through which exotic invasions occur.Invasive weeds are regarded as major threats to biodiversity because they can spread through communities, displacing or even eradicating native species. Over 25,000 invasive plant species have been documented in the United States, invading nearly 700,000 hectares per year, with a cost exceeding 34.5 billion dollars per year [1]. Multiple non-exclusive ecological hypotheses exist to explain plant invasion in new habitats [2]. The niche hypothesis suggests invaders are able to take advantage of unutilized resources in new environments [3]. The natural enemy release hypothesis suggests invaders escape their natural enemies when moving to new environments, allowing them to obtain high population densities [4]. The novel weapons hypothesis suggests that invaders come equipped with an arsenal of chemical weapons that are detrimental to the resident community of the invaded habitat [5]. The plant community in the invader's native habitat