Establishment of a photoautotrophic cell suspension culture of Arabidopsis thaliana for photosynthetic, metabolic, and signaling studies

Abstract

Plant cell suspension cultures have been used as model sys- tems to circumvent the problems associated with the analyses of a multi-factorial plant that is composed of multiple tissue and cell types exposed to diverse signals. A number of plant suspension cultures have proven to be valuable to study vari- ous topics including defense response, secondary metabolite formation, ion transport, gene regulation, and signal trans- duction (Roitsch and Sinha, 2002 and references therein). How- ever, most cultures reported to date, including the cultures from model species such as Arabidopsis (Christie and Jenkins, 1996), require the presence of sugar in the medium and are characterized by no or negligible photosynthetic activity (Roitsch and Sinha, 2002). For only a very limited number of species, such as Chenopodium rubrum, have true photoauto- trophic (PA) cultures been established (see references in Roitsch and Sinha, 2002). Such cultures combine the advan- tages of plant suspension cultures with carbon autotrophy and represent very powerful model systems for plant research. Unfortunately, for as-yet unknown reasons, it is very difficult to establish PA cultures (Widholm, 1992); hence, PA cultures from only a few crop species have been established. PA cul- tures have, however, been used to address various aspects of photosynthesis, herbicide effects, and secondary product formation from exclusively chloroplast localized pathways as well as in characterization of the metabolic changes occurring during the source–sink transition (Roitsch et al., 1995) and the coordinated regulation of primary metabolism and defense responses (Ehness et al., 1997). In parallel, a large number of mutant and transgenic Arabidopsis plants have been char- acterized with respect to their physiology, biochemistry, and molecular biology. That said, the establishment of a PA cell culture of Arabidopsis has, to date, proven elusive.