Antioxidant activity and ROS tolerance in triticale (×Triticosecale Wittm.) anthers affect the efficiency of microspore embryogenesis

Abstract

To verify the hypothesis that cell redox status regulates the process of microspore embryogenesis (ME), reactive oxygen species (ROS) generation and the activity of enzymatic and non-enzymatic antioxidants were analyzed in eight doubled haploid lines of triticale with significant differences in embryogenic potential. The analyses were performed in anthers excised from freshly cut tillers (control) and from low temperature (LT) pre-treated tillers (3 weeks at 4°C) in which ME has been initiated. Significant associations between ME effectiveness and the variables studied were found. In control cultures, high superoxide dismutase (SOD) activity appeared crucial for microspore viability. On the other hand, positive though non-linear correlation between ME effectiveness and H 2 O 2 generation, and negative correlation with catalase (CAT) activity suggest that some threshold level of H 2 O 2 is important for successful ME initiation. LT tillers pretreatment significantly increased H 2 O 2 accumulation, which had a negative effect on ME effectiveness. However, even high level of H 2 O 2 did not endanger cell viability as long as the cells exhibited high activity of ROS-decomposing enzymes (SOD, CAT and POX). The ability to sustain antioxidative enzyme activity under cold stress in the dark was another important requirement for high effectiveness of ME, allowing for the generation of the signal initiating microspore reprogramming and simultaneously protecting the cells from the toxic effects of ROS production. The role of antioxidative enzymes cannot be replaced even by high activity of non-enzymatic antioxidants. In conclusion, genetically controlled but environmentally modified cell tolerance to oxidative stress seems to play an important role in triticale ME.

Identification of QTLs associated with albino plant formation and some new facts concerning green versus albino ratio determinants in triticale (×Triticosecale Wittm.) anther culture

“…The situation changes after LT tillers treatment, which stimulated antioxidative system activity (SOD, CAT, POX) in responsive DH lines whereas in recalcitrant genotypes increased SOD activity was accompanied with diminished CAT and POX activity ( _ Zur et al 2014). In this case positive correlation found between GR regeneration and low molecular weight antioxidant activities in cultures of responsive DH lines seems to be in agreement with data published by Asif et al (2013).…”

“…First, drastic change in detected associations observed as result of LT tillers treatment confirmed earlier hypothesis ( _ Zur et al 2014( _ Zur et al , 2015 that this stress factor stimulate androgenesis by affecting cellular redox status and hormonal balance (Baek and Skinner 2012;Bonnecarrere et al 2011;Guo et al 2006). Among ROS, H 2 O 2 seems to be directly involved in androgenesis initiation ( _ Zur et al 2014), proper AS formation and plant regeneration.…”

“…It is supposed that CAT is responsible for scavenging high amounts of H 2 O 2 especially during stress whereas POX enabling the fine modulation of its level in specific locations, probably for signalling purposes. Despite the facts that exogenous stress can drastically reduce the number of plastids in microspores (Caredda et al 2000) and that in plants chilling temperatures can reduce up to 90 % of chlorophyll content (Tewari and Tripathy 1998) all presented data together with significantly higher CAT activity detected in anthers isolated from freshly cut tillers of recalcitrant DH lines in comparison with responsive DH lines ( _ Zur et al 2014) suggest that some level of H 2 O 2 is important not only for microspore reprogramming but also for successful transition from a non-photosynthetic proplastid to a functional chloroplast. Similarly, Makowska and Oleszczuk (2014) concluded that stress is capable of reprogramming a microspores themselves but not necessarily the plastids.…”

“…Among ROS, H 2 O 2 seems to be directly involved in androgenesis initiation ( _ Zur et al 2014), proper AS formation and plant regeneration. Without LT, osmotic stress induced by anther isolation acts as the signal stimulating microspore reprogramming.…”

“…These data has been received from additional experiments in which the anthers of highly responsive and highly recalcitrant DH lines selected out from the described above mapping population of triticale were used to analyze the changes induced by androgenesis-triggering low temperature stress treatment (3 weeks at 4°C). As the analytical methods and majority of received data has been reported elsewhere ( _ Zur et al 2014( _ Zur et al , 2015, here only some results of correlation analysis between albino/green plant regeneration ability and analyzed traits are presented.…”