Impact of Ascorbate-Glutathione Cycle Components on the Effectiveness of Embryogenesis Induction in Isolated Microspore Cultures of Barley and Triticale.

Iwona Żur,Monika Krzewska,Przemysław Kopeć,József Fodor,Anna Nowicka,Katarzyna Juzoń,Franciszek Janowiak,Ewa Dubas,Agnieszka Janas,Ewa Surówka,Balázs Barna

doi:10.3390/antiox10081254

Abstract

Enhanced antioxidant defence plays an essential role in plant survival under stress conditions. However, excessive antioxidant activity sometimes suppresses the signal necessary for the initiation of the desired biological reactions. One such example is microspore embryogenesis (ME)—a process of embryo-like structure formation triggered by stress in immature male gametophytes. The study focused on the role of reactive oxygen species and antioxidant defence in triticale (×Triticosecale Wittm.) and barley (Hordeum vulgare L.) microspore reprogramming. ME was induced through various stress treatments of tillers and its effectiveness was analysed in terms of ascorbate and glutathione contents, total activity of low molecular weight antioxidants and activities of glutathione–ascorbate cycle enzymes. The most effective treatment for both species was a combination of low temperature and exogenous application of 0.3 M mannitol, with or without 0.3 mM reduced glutathione. The applied treatments induced genotype-specific defence responses. In triticale, both ascorbate and glutathione were associated with ME induction, though the role of glutathione did not seem to be related to its function as a reducing agent. In barley, effective ME was accompanied by an accumulation of ascorbate and high activity of enzymes regulating its redox status, without direct relation to glutathione content.

Highlights

Each stress that disturbs cellular homeostasis and oxygen metabolism leads to the generation of reactive oxygen species (ROS) and induces the so-called ‘oxidative stress’ [1].Effective antioxidant protection in cells is needed for survival under stress conditions, especially for plants that do not have the possibility of the ‘fight-or-flight’ response.ROS are no longer considered only the inevitable, toxic by-products of aerobic metabolism—their role proved to be essential in many life processes [1,2,3]
The number of microspores obtained from DH19 was significantly higher than that of DH28, whereas the process of microsporogenesis was effective in the studied barley cultivars, producing an average of 26,500 microspores per spike
The analysis of our data suggests that the very subtle, dynamic homeostasis between ROS production and scavenging determines the effectiveness of microspore reprogramming towards sporophytic development

Summary

Introduction

Each stress that disturbs cellular homeostasis and oxygen metabolism leads to the generation of reactive oxygen species (ROS) and induces the so-called ‘oxidative stress’ [1].Effective antioxidant protection in cells is needed for survival under stress conditions, especially for plants that do not have the possibility of the ‘fight-or-flight’ response.ROS are no longer considered only the inevitable, toxic by-products of aerobic metabolism—their role proved to be essential in many life processes [1,2,3]. Each stress that disturbs cellular homeostasis and oxygen metabolism leads to the generation of reactive oxygen species (ROS) and induces the so-called ‘oxidative stress’ [1]. Depending on the subtle and dynamic homeostasis between production and scavenging, ROS can be considered as life-threatening or life-saving molecules, and the latter possibility is based on their involvement in stress signalling and initiation of defence reactions. Our earlier studies [4,5] clearly showed that the initiation of microspore embryogenesis (ME) was associated with ROS generation. This is fully justified as the process—highly resembling zygotic embryo formation in planta, induced in immature male gametophyte cells in response to stress—involves very stressful procedures of anther or

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Conclusion