Abstract

Lepidium campestre (field cress) has been selected for domestication. It is proposed to be cultivated as a catch crop in a spring cereal and produce a seed oil of industrial quality the following year(s). This crop system will help to alleviate the problem of nutrient leaching from agricultural soils. The oil produce will provide an alternative to fossil oil in certain industrial applications. This thesis addresses the issues of seed dispersal, seed oil quality and also includes a field trial evaluation of L. campestre. A shoot regeneration protocol has been developed for L. campestre in order to enable a transformation procedure. The most important factors include a pretreatment on 2,4-D and a temporary starvation treatment. The combination of plant growth hormones in the regeneration medium was of little importance. For transformation, a number of factors for co-cultivation with Agrobacterium tumefaciens have been evaluated. So far, however, there has been little success. Microscopical studies on L. campestre fruits have identified a basic architecture as well as a dehiscence zone (DZ) that are important for seed dispersal. A gene controlling the development of the DZ, the INDEHISCENT, has been cloned from L. campestre. The function of the gene has been confirmed through functional complementation of the corresponding mutant, as well as RNAi down regulation, in A. thaliana. To modify the seed oil quality, the genes encoding two important enzymes, the FATTY ACID DESATURASE 2 and the FATTY ACID ELONGASE 1, have been cloned from L. campestre. The functions of these genes have been confirmed through functional complementation of the corresponding A. thaliana mutants. A three-year field trial with L. campestre undersown in spring barley demonstrated the high seed yield potential of this species. A positive effect on the barley yield was recorded when L. campestre was undersown with short row distance.