Progress In Understanding The Genomics Of Invasiveness In a Model Perennial Weed

Leafy spurge is an invasive perennial rangeland weed with multiple introductions into North America. Ecotypes introduced in the 1800’s from Eastern Europe populations have proven to be aggressive and invasive. Due to significant losses caused by leafy spurge (> $4 million dollars annually), resources have been available to study this weed. Consequently, numerous genomics tools have been developed to assist in studying this invasive perennial including an extensive high quality EST database and a 23,000 element microarray.  Here we report additional advances including the construction of a two BAC libraries with a total of 5X coverage of the 2.1 Gb leafy spurge genome, and full genome sequencing from 8 different libraries ranging in size from 200-800 bases using Illumina technologies. Additionally, we have utilized the microarrays to compare gene expression patterns in leaf tissue from four populations collected near Kiev in the Ukraine to four populations collected near Fargo ND. Plants were collected at the same time of day/year and were experiencing similar light and temperatures conditions at the time of collection. About 1349 genes were differentially expressed and gene set enrichment analysis indicated that plants from the Ukraine were expressing genes with ontologies associated with defense responses at a higher level than were plants growing in the US. Likewise, plants in the US were expressing genes with ontologies associated with carbon accumulation and growth at higher levels than the Ukrainian plants.