Influence of anti- and prooxidants on rhizogenesis from hypocotyls of Mesembryanthemum crystallinum L. cultured in vitro

M Libik-Konieczny,Ż Michalec-Warzecha,M Kozieradzka-Kiszkurno,J Bizan,Z Miszalski,R Konieczny

doi:10.1007/s11738-017-2466-x

Abstract

The enrichment with antioxidants (glutathione or ascorbate) or prooxidants (alloxan, methylviologen, hydrogen peroxide) of root inducing medium significantly decreased rhizogenesis frequency (alloxan, hydrogen peroxide) or inhibited roots regeneration (ascorbate, methylviologen) during the in vitro culture of Mesembryanthemum crystallinum L. hypocotyls. The adventitious roots morphology, root hairs length and density, was also influenced. Changes in the rhizogenesis course were related to the differences in hydrogen peroxide concentration during following days of culture between explants exhibiting morphogenic potential and those without the ability to form adventitious roots. In explants with morphogenic potential, rhizogenesis induction was always accompanied by a high level of hydrogen peroxide followed by the decrease in H2O2 content in following days. In contrast, in the explants without regeneration potential, the level of hydrogen peroxide was increasing during the culture period. Activity patterns of superoxide dismutase (SOD) and guaiacol peroxidase (POX) in the following days of culture were similar in the explants exhibiting regeneration potential cultured on different media. Total activity of SOD decreased during initial days of culture and then increased due to the activation of additional SOD isoform described as MnSODII. The activity of POX was low during the rhizogenesis induction, and then increased during following days of culture; the increase was correlated with the decrease in hydrogen peroxide content. In the explants without the ability to regenerate roots, the total activity of SOD was low throughout the whole culture period, whereas the POX activity was significantly higher than in hypocotyls with regeneration potential. It might be concluded that the increase in hydrogen peroxide during initial stages of rhizogenesis and the induction of MnSODII are prerequisites for adventitious roots formation from hypocotyls of M. crystallinum, independently in the presence of anti- or prooxidant in the culture medium.

Highlights

Many factors influence induction and course of in vitro plants regeneration
Hypocotyls grown on root inducing medium (RIM) produced roots with the frequency of 90%
Differences in the morphology between roots produced on the control medium (RIM) and roots produced on the medium containing reduced glutathione (RIM ? GSH) was based on the production of slimmer roots characterized with less abundant root hairs (Table 1; Fig. 1)

Summary

Introduction

Many factors influence induction and course of in vitro plants regeneration. They include the explants properties, the chemical composition of the medium as well as physical culture conditions. It was found that class III heme peroxidases (POXs) in roots of Arabidopsis (Tsukagoshi et al 2010) control the balance of ROS between the cell proliferation and the cell elongation phase during induction of differentiation process This regulatory pathway functions independently of phytohormone signaling. We hypothesize that the shift of redox balance into the direction of ROS scavenging activity or ROS production activity might significantly influence the rhizogenesis course To verify this hypothesis we compared the activity of some antioxidant enzymes, endogenous H2O2 content, and we visualized the distribution of H2O2 in the hypocotyl explants cultured on the media containing auxin alone or in combination with different antioxidants (reduced glutathione, reduced ascorbate) or prooxidants (methylviologen, alloxan, hydrogen peroxide)

Materials and methods

Results

Discussion