Biochemical response of hybrid black poplar tissue culture (Populus × canadensis) on water stress

In this study, poplar tissue culture (hybrid black poplar, M1 genotype) was subjected to water stress influenced by polyethyleneglycol 6000 (100 and 200 mOsm PEG 6000). The aim of the research was to investigate the biochemical response of poplar tissue culture on water deficit regime. Antioxidant status was analyzed including antioxidant enzymes, superoxide-dismutase (SOD), catalase (CAT), guiacol-peroxidase (GPx), glutathione-peroxidase (GSH-Px), glutathione-reductase, reduced glutathione, total phenol content, Ferric reducing antioxidant power and DPPH radical antioxidant power. Polyphenol oxidase and phenylalanine-ammonium-lyase were determined as enzymatic markers of polyphenol metabolism. Among oxidative stress parameters lipid peroxidation, carbonyl-proteins, hydrogen-peroxide, reactive oxygen species, nitric-oxide and peroxynitrite were determined. Proline, proline-dehydrogenase and glycinebetaine were measured also as parameters of water stress. Cell viability is finally determined as a biological indicator of osmotic stress. It was found that water stress induced reactive oxygen and nitrogen species and lipid peroxidation in leaves of hybrid black poplar and reduced cell viability. Antioxidant enzymes including SOD, GPx, CAT and GSH-Px were induced but total phenol content and antioxidant capacity were reduced by PEG 6000 mediated osmotic stress. The highest biochemical response and adaptive reaction was the increase of proline and GB especially by 200 mOsm PEG. While long term molecular analysis will be necessary to fully address the poplar potentials for water stress adaptation, our results on hybrid black poplar suggest that glycine-betaine, proline and PDH enzyme might be the most important markers of poplar on water stress and that future efforts should be focused on these markers and strategies to enhance their concentration in poplar.

Effects of long-term salicylic acid pre-treatment on tomato ( Lycopersicon esculentum Mill. L.) salt stress tolerance: Changes in glutathione S-transferase activities and anthocyanin contents

The aim of the present study was to investigate the effect of salicylic acid (SA) pre-treatment on the salt stress acclimation of tomato plants ( Lycopersicon esculentum Mill. L. cv. Rio Fuego). The antioxidant defence and detoxifying capacity of the tissues were analysed by measuring the accumulation of soluble, non-enzymatic antioxidants (anthocyanins) and the activities of glutathione S-transferases (GSTs) at low (10 −7 M) and high (10 −4 M) SA concentrations in plants exposed to 100 mM NaCl. GSTs are a diverse group of enzymes that catalyse the detoxification of xenobiotics and other toxic organic compounds, and anthocyanins are among the few endogenous substrates that bind to GSTs and are sequestered to the vacuole. It was found that 10 −4 M SA pre-treatment improved the acclimation of tomato to high salinity. SA pre-treatments increased the accumulation of anthocyanins both in the presence and absence of 100 mM NaCl. The extractable GST activity of tissues increased under salt stress in young leaves and roots of the control and in plants pre-treated with 10 −4 M SA, while the extractable GST activity in these organs was reduced by 10 −7 M SA. It is suggested that elevated GST activity is a prerequisite for successful acclimation to high salinity in tomato plants pre-treated with SA, but it may also be a symptom of tissue senescence.

Influence of benzo[a]phenothiazines on the element content of two tobacco tissue cultures differing in hormone requirement

Cell proliferation and tumor formation are closely connected with hormone metabolism. We report the effect of four benzo[a]phenothiazines (12H-benzo[a]phenothiazine (1), 5-oxo-5H-benzo[a]phenothiazine (2), 10-methyl-12H-benzo[a]phenothiazine (3), and 6-hydroxy-5-oxo-5H-benzo[a]phenothiazine (4) on the growth and changes in the element compositions (Ca, Cl, Cu, I, K, Mg, Mn and Na) of auxin autotrophic and heterotrophic tobacco tissue cultures. The concentration levels of these ions were followed by means of reactor neutron activation analysis.

Effect of chlorpromazine and benzo[a]phenothiazines on heterotrophic auxin requiring and autotrophic auxin non-requiring tobacco tissue cultures

Chlorpromazine and four benzo[a]phenothiazines were tested on the growth and auxin level of auxin requiring heterotrophic and auxin non-requiring autotrophic tobacco tissue cultures originating from transgenic plants. The auxin content was followed by the expression of GUS reporter gene connected with auxin inducible mass promoter. The benzo[a]phenothiazines had a higher antiproliferative effect than chlorpromazine. The exogenous auxin non-requiring autotrophic callus was more sensitive than the auxin requiring heterotrophic callus (Based on the low GUS activity). The reduced growth of auxin autotrophic tissues may be due to the low endogenous auxin content.