Differential induction of Orobanche seed germination by Arabidopsis thaliana

Parasitic plants. including the root holoparasites Orobanche spp., cause de vastating damage to crops worldwide. Arabidopsis thaliana (L. is widely use d an amenable model for the study of plant biology, including plant-pathoge n interactions. Bringing the two plants together in a controlled system wil l enable the study of the molecular and genetic basis involved in host-para sitic plant interactions and should provide tools for the detection of gene s responsible for incompatibility and resistance responses. The objective o f this study was to screen Arabidopsis lines for reduced germination of Oro banche seeds. A 96-cell well bioassay was developed to test the potential o f lines, ecotypes and mutants of Arabidopsis to induce germination of Oroba nche. Screening of 50 A. thaliana ecotypes did not reveal non-inducing ecot ypes. Screening of 13 000 A. thaliana fast neutron mutated M2 plants detect ed 94 non-inducing mutant plants of which 34 were rescued. self pollinated, and M3 seeds collected. M3 seedlings from five lines were reduced in their ability to induce germination. In a separate assay, we determined that the reduced germination rates corresponded with reduced distance from the root s at which germination occur red. While further studies are necessary to de termine the segregation of low germination phenotypes, these lines might pr ove useful for studying the genetic basis of variation in germination stimu lant production in A. thaliana. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.