Zhenzhen Cai

Exudation: an expanding technique for continuous production and release of secondary metabolites from plant cell suspension and hairy root cultures

This review addresses methods of obtaining secondary metabolites from plant cell suspension and hairy root cultures and their exudates, particularly the physiological mechanisms of secondary metabolites release and trafficking. The efficiency for product recovery of metabolites can be increased by various methods, based on the principle of continuous product release into the cultivation medium. The most common methods for metabolite recovery are elicitation, influencing membrane permeability, and in situ product removal. The biosynthetic pathways can be influenced by cultivation conditions, transformation, or application of elicitors. The membrane permeability can be altered through the application of chemical or physical treatments. Product removal can be greatly increased through a two-phase system and the introduction of absorbents into the cultivation medium. In this review, we describe some improved approaches that have proven useful in these efforts.

Effects of pulsed electric field on secondary metabolism of Vitis vinifera L. cv. Gamay Fréaux suspension culture and exudates.

Plant cell cultures provide a large potential for the production of secondary metabolites. Through the application of different physical and chemical cell stress factors, we investigated the production of the secondary metabolites in plant cell cultures. The effects of pulsed electric field (PEF) and ethephon on growth and secondary metabolism, particularly anthocyanins and phenolic acids synthesis, were investigated by using suspension culture of Vitis vinifera L. cv. Gamay Fréaux as a model system. Anthocyanins were measured by spectrophotometer and extracellular phenolic acids were determined by high-performance liquid chromatography. The compounds were identified by liquid chromatography–mass spectrometry and nuclear magnetic resonance. After the treatments with PEF and ethephon, the concentrations of anthocyanins and phenolic acids in cell culture were higher than in the control, without loss of biomass. The combination of PEF treatment and ethephon improved secondary metabolites formation. Production levels of extracellular phenolic acids, 3-O-glucosyl-resveratrol were increased by PEF and ethephon treatments. The results show that PEF induced a defense response of plant cells and may have altered the cell/membrane’s dielectric properties. PEF, an external stimulus or stress, is proposed as a promising new abiotic elicitor for stimulating secondary metabolites biosynthesis in plant cell cultures.

Enhanced anthocyanins and resveratrol production in Vitis vinifera cell suspension culture by indanoyl-isoleucine, N-linolenoyl-l-glutamine and insect saliva

The effects of two synthetic elicitor indanoyl-isoleucine (In-Ile), N-linolenoyl-L-glutamine (Lin-Gln) and one biotic elicitor insect saliva (from Manduca sexta larvae) on plant cell cultures with respect to the induction of secondary metabolite production were investigated. Stimulated production of secondary metabolites, particularly anthocyanins in plant cells and phenolic acids in culture medium, was studied by using suspension culture of Vitis vinifera L. cv. Gamay Fréaux as a model system. In the treatments with In-Ile, the production of anthocyanins was enhanced 2.6-fold. In-Ile, Lin-Gln and saliva significantly elevated the accumulation of phenolic acids, particularly 3-O-glucosyl-resveratrol. The used elicitors did not suppress cell growth. Secondary metabolites were differently responsive to elicitation. 3-O-glucosyl-resveratrol was the predominant phenolic acid in V. vinifera cell culture, and its production was significantly stimulated by saliva, with 7.0-fold of the control level 24 h after treatment. The production of 4-(3,5-dihydroxy-phenyl)-phenol was significantly stimulated by In-Ile with 6.4-fold of the control level 24 h after treatment.

Chitosan or yeast extract enhance the accumulation of eight phenolic acids in cell suspension cultures of Malus × domestica Borkh

Summary The effects of chitosan or a yeast extract on the production of secondary metabolites and on the induction of plant defence responses in cell suspension cultures of Malus × domestica Borkh. were investigated. Chitosan or yeast extract enhanced the production of phenolic acids by 1.5-fold and by 2.0-fold after 3 d of culture following elicitor treatment, respectively, compared to untreated control cell suspension cultures. The production of specific phenolic acids responded differently to chitosan and to yeast extract. Among the dominant phenolic acids, the production of p-coumaric acid was stimulated by chitosan and by yeast extract up to 10.3-fold and 5.1-fold within 3 d, respectively, compared with the concentration in control cultures within 3 d. Chlorogenic acid concentrations were increased 2.7-fold within 3 d of culture by yeast extract treatment compared to the controls. There was no difference in the amount of phenolic acids released into the culture medium between control and elicitor-treated cultures, indicating that these elicitors had no effect on the release or transport of phenolic acids. In addition, phenylalanine ammonia-lyase (PAL) activity was reduced up to 33% by elicitation. While yeast extract maintained control levels of cell growth in culture, chitosan inhibited cell growth in culture by 72%.