Glutathione provides antioxidative defence and promotes microspore-derived embryo development in isolated microspore cultures of triticale (\xd7\u2009Triticosecale Wittm.)

Iwona Żur,Franciszek Janowiak,Ewa Dubas,Jozsef Fodor,Monika Krzewska,Kamil Zieliński

doi:10.1007/s00299-018-2362-x

Abstract

Key messageDepending on the capability for stress adaptation, the role played by glutathione in microspore embryogenesis consists of both antioxidative activity and stimulation of embryo-like structure development.The efficiency of microspore embryogenesis (ME) is determined by the complex network of internal and environmental factors. Among them, the efficient defence against oxidative stress seems to be one of the most important. The present study confirms this hypothesis showing the positive effect of glutathione—the most abundant cellular antioxidant—on ME in isolated microspore cultures of triticale (× Triticosecale Wittm.). For the first time, low temperature (LT) pre-treatment of tillers was combined with the exogenous application of glutathione and associated with the total activity of low-molecular weight antioxidants, the endogenous content and redox status of glutathione, and the effectiveness of ME. The results indicate that efficient antioxidative defence is the first, although not the only, prerequisite for effective ME. In responsive genotypes, LT alone stimulated antioxidative defence and decreased cell redox status, which was associated with increased cell viability and high frequency (ca. 20%) of microspore reprogramming. Application of glutathione had no effect either on the microspore viability or on the initial number of embryogenic microspores. However, it increased the number of embryo-like structures, probably by stimulating the next phases of its development. In recalcitrant genotypes, the main role of glutathione seems to be its participation in cell protection from oxidative stress. However, even enhanced antioxidative activity, which sustained cell viability and increased the number of embryogenic microspores, was insufficient for efficient haploid/doubled haploid plant production. Evidently, there are still other defective elements in the complex network of factors that regulate the process of ME.

Highlights

The process of microspore embryogenesis (ME) is an alternative pathway of development, available for in vitro cultured immature pollen grains, which leads to the formation of haploid embryo-like structures (ELSs), able to regenerate haploids/doubled haploids (DHs)
The studied DH lines of winter triticale were selected from the mapping population ‘Saka 3006’ × ‘Modus’ derived using the method of distant crosses with maize (Wędzony 2003; Tyrka et al 2011)
The population composed of 90 DH was carefully examined in respect of its embryogenic potential by anther culture method and used as the model in our earlier studies focused on physiological, metabolomic and molecular aspects of ME (Żur et al 2012, 2014a, b, 2015; Krzewska et al 2012, 2015, 2017)

Summary

Introduction

The process of microspore embryogenesis (ME) is an alternative pathway of development, available for in vitro cultured immature pollen grains (microspores), which leads to the formation of haploid embryo-like structures (ELSs), able to regenerate haploids/doubled haploids (DHs). The. Plant Cell Reports (2019) 38:195–209 reason for this setback is the complexity and multifactorial nature of the process, which depends significantly on both endogenous and environmental factors and on an intricate network of their specific interactions. One of the most important components of stress tolerance is an effective antioxidative system composed of both enzymatic and low-molecular weight (LMW) antioxidants, protecting the cells from the effects of reactive oxygen species (ROS) generation (Mittler 2002). In several plant species gene-encoding enzymes involved in antioxidative defence [glutathioneS-transferase (GST), oxalate oxidase] were up-regulated in response to the treatment initiating ME (Vrinten et al 1999; Jacquard et al 2009; Sánchez-Díaz et al 2013; Żur et al 2014b). Increased accumulation of proteins typical for cell defence against oxidative stress (e.g., GST, l-ascorbate peroxidase) during ME induction was reported (Cordewener et al 2009; Uváčková et al 2012; Krzewska et al 2017)

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Conclusion