Genetic characterization of a red color morph of Euphorbia esula subsp. esula (Euphorbiaceae) in the floodplains of Saône (Eastern France)

Authors: AUGE, M - European Biological Control Laboratory (EBCL); BON, MC - European Biological Control Laboratory (EBCL); HARDION, L - Université De Strasbourg: Accueil; LE BOURGEOIS, T - Centro De Cooperation Internationale En Recherche Agronomique Pour Le Development (CIRAD); SFORZA, R - European Biological Control Laboratory (EBCL)

Submitted to: Botany
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/11/2016
Publication Date: 6/7/2016
Citation: Auge, M., Bon, M., Hardion, L., Le Bourgeois, T., Sforza, R. 2016. Genetic characterization of a red color morph of Euphorbia esula subsp. esula (Euphorbiaceae) in the floodplains of Saône (Eastern France). Botany. 10.1139/cjb-2016-0067.

Interpretive Summary: Leafy spurge is an important invasive alien weed in rangelands of the western USA. It has been a target of classical biological control, but it is not well known how vegetation management can interact with biological control agents to both control the invasive weed and improve harvest of forage grasses. Research was conducted in the native region of this weed in a semi-natural habitat in France that is managed for both mowing hay and cattle grazing to determine how to integrate mowing with biological control to both increase the harvest of uncontaminated hay and sustainably reduce the area of infestations. During the course of these studies a red variety of the plant was discovered, so genetic analysis was conducted to determine if this represented a genetically distinct type of plant, that might affect management decisions. The results indicate no reason to consider managing the red variety differently than the normal green one.

Technical Abstract: The invasive leafy spurge, Euphorbia esula L (Euphorbiaceae) is an The invasive leafy spurge, Euphorbia esula L (Euphorbiaceae) is an emerging weed in the floodplains of the Val de Saône France, that displaces native flora and desirable forage species by forming dense monotypic stands. It is considered toxic to cattle. While conducting research on integrated management of leafy spurge, we found two different morph colors: the common “green” variant and an uncommon "red" variant. We sequenced the plastid trnT-trnF region and counted the number of chromosomes of specimens of both color morphs. Results showed that both morphs share two of the three cpDNA haplotypes found in the studied area and both are hexaploids (2n=6x=60). These results suggest that the red morph is an environmental variant of E. esula subsp. esula, rather than being a genetically distinct variety. Our results indicated that leafy spurge populations in this region consist of a genetically diverse population structure composed of three cpDNA haplotypes, two of which are shared by the two color morphs.