Plant cell and tissue cultivations are of growing interest for the production of structurally complex and expensive plant-derived products, especially in pharmaceutical production. Problems with up-scaling, low yields and high-priced process conditions result in an increased demand for models to provide comprehension, simulation, and optimization of production processes. In the last 25 years, many models have evolved in plant biotechnology; the majority of them are specialized models for a few selected products or nutritional conditions. In this article we review, delineate, and discuss the concepts and characteristics of the most commonly used models. Therefore, the authors focus on models for plant suspension and submerged hairy root cultures. The article includes a short overview of modeling and mathematics and integrated parameters, as well as the application scope for each model. The review is meant to help researchers better understand and utilize the numerous models published for plant cultures, and to select the most suitable model for their purposes.

Plant cell and tissue cultivations are of growing interest for the production of structurally complex and expensive plant-derived products, especially in pharmaceutical production. Problems with up-scaling, low yields and high-priced process conditions result in an increased demand for models to provide comprehension, simulation, and optimization of production processes. In the last 25 years, many models have evolved in plant biotechnology; the majority of them are specialized models for a few selected products or nutritional conditions. In this article we review, delineate, and discuss the concepts and characteristics of the most commonly used models. Therefore, the authors focus on models for plant suspension and submerged hairy root cultures. The article includes a short overview of modeling and mathematics and integrated parameters, as well as the application scope for each model. The review is meant to help researchers better understand and utilize the numerous models published for plant cultures, and to select the most suitable model for their purposes.

Die Biosynthese von Chlorophyll ist komplex und umfasst mehr als ein Dutzend enzymatische Schritte. Es ist nur allzu selbstverständlich, dass eine Deregulation der Chlorophyllsynthese globale Effekte auf die Zelle hat. Um diese Konsequenzen näher zu beleuchten, wurden Arabidopsis thaliana Pflanzen mit chemisch induzierter Deaktivierung von zwei Chlorophyllbiosynthesegenen (CHLH bzw. CHL27) erzeugt sowie photoautotophe Zellsuspensionskulturen von Arabidopsis thaliana hinsichtlich kurzzeitig induzierter Signalprozesse untersucht. Die Resultate verdeutlichen, dass durch Fehlregulationen innerhalb der Chlorophyllbiosynthese erzeugte reaktive Sauerstoffspezies die Transkriptionskontrolle kernkodierter Gene beeinflussen. Die Untersuchung eines enzymatischen Schrittes der Chlorophyllbiosynthese trat in dieser Arbeit in den Hauptfokus: Die Bildung des fünften, isozyklischen Ringes im Chlorophyllmolekül, katalysiert durch das bisher unzureichend erforschte Enzym Mg-Protoporphyrin-IX-monomethylester-Cyclase (Cyclase). Anhand von transgenen Cyanobakterien und Pflanzen sollte das noch unbekannte Gen ycf54 hinsichtlich seiner physiologischen Funktion in dem Cyclase-Enzymschritt analysiert werden. Das Fehlen von Ycf54 in Synechocystis sp. PCC6803 bzw. des homologen LCAA-Proteins in Nicotiana tabacum und Arabidopsis thaliana führt zu starken Cyclase-Substrat-Akkumulationen, verringerten Chlorophyllgehalten und reduzierten Ycf59- bzw. CHL27-Proteingehalten. Ein Mangel von Ycf54/LCAA beeinträchtigt daher die Funktionalität des Cyclase-Komplexes und scheint sich zudem interessanterweise auch auf die Stabilität photosynthetischer Antennenkomplexe auszuwirken. Mittels Pulldown-Assays konnte für Arabidopsis thaliana die direkte physikalische Interaktion zwischen LCAA und CHL27 bestätigt werden. Darüber hinaus sind erste Hinweise für die Ferredoxin-NADP-Reduktase als potenziellen Interaktionspartner gezeigt. / Synthesis of chlorophyll is a complex metabolic process and encompasses more than a dozen enzymatic reactions. It is self-evident that a deregulation of chlorophyll biosynthesis evokes global cellular impacts. To elucidate these consequences Arabidopsis thaliana plants with chemically inducible deactivation of two chlorophyll biosynthesis genes (CHLH and CHL27, respectively) were generated and photoautotrophic cell suspension cultures of Arabidopsis thaliana were used for short induced signal processes. The results illustrate that reactive oxygen species provoked by a deregulated chlorophyll synthesis affect the control of transcription of nuclear genes. The investigation of one enzymatic step of chlorophyll biosynthesis was placed as main focus: The formation of the isocyclic ring of the chlorophyll molecule catalyzed by the Mg protoporphyrin IX monomethyl ester cyclase (short: cyclase), an enzyme which is not fully investigated so far. The still unknown hypothetical chloroplast open reading frame (ycf) ycf54 should be analyzed concerning it’s physiological function in the enzymatic step of the cyclase using transgenic cyanobacteria and plants. Lack of Ycf54 in Synechocystis sp. PCC6803 and the homologous LCAA protein in Nicotiana tabacum and Arabidopsis thaliana, respectively, leads to chlorophyll deficiency, a strong accumulation of the cyclase substrate and reduced protein contents of Ycf59 and CHL27, respectively. A deficit of Ycf54/LCAA impairs the functionality of the cyclase complex and also might compromise the stability of photosynthetic antenna complexes. Using pull-down assays a direct physical interaction between LCAA and CHL27 could be confirmed. Additionally, first evidences for ferredoxin NADP reductase as a potential interaction partner was given.