Parasitism represents the most extreme interaction between plants. Despite our general understanding of how parasitism and the loss of photosynthesis affect autotrophy-related genes, we know nothing about the nuclear-encoded factors that are involved or affected by the transition to an obligate parasitic lifestyle and that play a major role in the functional adaptation to this extraordinary lifestyle in plants. We assume that functional adaptation is not only relevant for heterotrophic nutrient cycling but also for the adaptation to the newly indispensable biotic environment, the host system.
Using genome, transcriptome and proteome data of a variety of parasitic plants with different trophic specialization in an explicit phylogenetic framework, we aim to assess the series of genetic causes and consequences of the transition from autotrophy to a fully parasitic lifestyle. We will concentrate on the functional adaptation of the plastid organelle and its interaction with the nucleus. We will focus on eudicot parasitic lineages, particularly on dodders (Cuscuta, Convolvulaceae), broomrapes (Orobanchaceae) and mistletoes (Viscaceae), not only because of their importance as noxious agricultural pests, but also because all these lineages exhibit trophic transition series. Existing data from both groups will be compiled and supplemented with new data from field surveys during which physiological and ecological parameters will be gathered and plant material for further molecular characterization will be selected. The data will contribute significantly to unraveling the biology of parasitic plants at the molecular level. Besides its relevance for basic research and evolutionary biology, understanding the role of plastids in parasitic plants is of great importance for breeding of parasitic plant-resistant crops as part of an improvement of pest control strategies, which is one of the research areas in focus by several Horizon 2020 calls.