Host status and reaction of Arabidopsis thaliana ecotypes to infection by the northern root-knot nematode (Meloidogyne hapla)

A phenotypically and geographically diverse collection of 45 Arabidopsis th aliana ecotypes was evaluated for its reaction to the northern root-knot ne matode (Meloidogyne hapla) under greenhouse conditions. A significant ecoty pe effect was observed for both criteria used for host reaction assessment: namely, root-gall rating (RGR) and nematode reproductive index (RI). A non -host (non-galling) response was not detected in this germplasm collection. The majority of the ecotypes showed high degrees of RGR and RI. However, s ome medium-late maturing ecotypes such as 'CS-1540' and 'CS-6028' (both col lected in the UK) displayed high RGR but in association with very reduced R I.. The confirmation of A. thaliana as an experimental host of M. hapla and the identification of differential levels of response to infection by this endoparasitic nematode provides the opportunity for genetic and molecular characterization of a new set of plant genes expressed during plant-nematod e interaction. A. thaliana is the smallest and the best characterized genom e among plant species, which may facilitate gene isolation and cloning. Thi s may hasten transgenic transfer to economically important host plants of t he genetic factors controlling low RI levels identified in some A. thaliana ecotypes.