Defensive and secondary metabolism in plant tissue cultures, with special reference to nicotinamide, glutathione and oxidative stress

Abstract

The purpose of the presentation is to interconnect and illuminate certain parts of metabolism regarding stress signalling and defensive functions, including secondary metabolism in intact plants and plant tissue cultures. Increased cell/tissue levels of reactive oxygen species like H202, 0 2 and .OH and the metabolism of glutathione, are linked to defensive/secondary metabolism and tissue differentiation. Special attention is paid to nicotinamide. A hypothetical role of nicotinamide and its metabolites as stress signals is also put forward especially in connection with hypomethylation of DNA. A role of DNA hypomethylation, as a link between various types of stressors and the induction of plant defensive metabolism, is discussed. We suggest that nicotinamide or nicotinamide based substances may be of value within biotechnology for the production of valuable substances as well as for plant protection.

Metabolite profiling of symbiont and host during thermal stress and bleaching in a model cnidarian-dinoflagellate symbiosis

“…This compound is the precursor to the essential coenzymes nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP). These coenzymes facilitate many oxidation and reduction reactions in living cells, which include linking the TCA cycle and oxidative phosphorylation (Berglund and Ohlsson, 1995). In Symbiodinium, as in other primary producers, NADP + is a major acceptor of electrons in photosystem I, which in turn reduces the production of ROS (Takahashi and Murata, 2008).…”

“…In Symbiodinium, as in other primary producers, NADP + is a major acceptor of electrons in photosystem I, which in turn reduces the production of ROS (Takahashi and Murata, 2008). In higher plants, nicotinamide has been identified as a signal molecule of DNA damage and oxidative stress, which facilitates a number of defence-related metabolic reactions (Berglund, 1994;Berglund and Ohlsson, 1995). A similar defence and signalling mechanism may also function in the cnidarian-dinoflagellate symbiosis, though this awaits confirmation.…”

Anthraquinones production, hydrogen peroxide level and antioxidant vitamins in Morinda elliptica cell suspension cultures from intermediary and production medium strategies

“…The H 2 O 2 level in the P medium was ninefold and fourfold that in the M and G media, respectively. It has been suggested that oxidative burst and secondary metabolism are closely related (Berglund and Ohlsson 1995;Zhao et al 2001). Despite a high level of oxidative stress, application of the P medium strategy not only produced high cell growth and high AQ but also produced superior antioxidant vitamin levels.…”

UV‐B‐ and oxidative stress‐induced increase in nicotinamide and trigonelline and inhibition of defensive metabolism induction by poly(ADP‐ribose)polymerase inhibitor in plant tissue

“…It has been hypothesized that nicotinamide (NIC) and/or its metabolites nicotinic acid and N-methyl nicotinic acid (trigonelline; TRIG) may constitute a link between various types of stresses, especially stress causing DNA strand breaks, and the induction of defensive metabolism in eukaryotic cells [9][10][11][12]. An important source of NIC release in response to stress is the DNA strand break-activated eukaryotic enzyme poly(-ADP-ribose)polymerase (PADPRP) [13,14].…”