Seed 1-Cysteine Peroxiredoxin Antioxidants Are Not Involved in Dormancy, But Contribute to Inhibition of Germination during Stress

Abstract

Peroxiredoxins (Prx) are thiol-dependent antioxidants containing one (1-cysteine [-Cys]) or two (2-Cys) conserved Cys residues that protect lipids, enzymes, and DNA against reactive oxygen species. In plants, the 1-Cys Prxs are highly expressed during late seed development, and the expression pattern is dormancy related in mature seeds. We have expressed the Arabidopsis 1-Cys Prx AtPER1 in Escherichia coli and show that this protein has antioxidant activity in vitro and protects E. coli in vivo against the toxic oxidant cumene hydroperoxide. Although some 1-Cys Prxs are targeted to the nucleus, a green fluorescent protein-AtPER1 fusion protein was also localized to the cytoplasm in an onion epidermis subcellular localization assay. It has been proposed that seed Prxs are involved in maintenance of dormancy and/or protect the embryo and aleurone layer surviving desiccation against damage caused by reactive oxygen species. These hypotheses were tested using transgenic Arabidopsis lines overexpressing the barley (Hordeum vulgare) 1-Cys PER1 protein and lines with reduced levels of AtPER1 due to antisensing or RNA interference. We found no correlation between Prx levels and the duration of the after-ripening period required before germination. Thus, Prxs are unlikely to contribute to maintenance of dormancy. RNA interference lines almost devoid of AtPER1 protein developed and germinated normally under standard growth room conditions. However, seeds from lines overexpressing PER1 were less inclined to germinate than wild-type seeds in the presence of NaCl, mannitol, and methyl viologen, suggesting that Prx can sense harsh environmental surroundings and play a part in the inhibition of germination under unfavorable conditions.

The Peroxiredoxin and Glutathione Peroxidase Families in Chlamydomonas reinhardtii

“…The plastidial localization of 2-cys PRXs was confirmed experimentally in several organisms (Baier and Dietz 1997;Genot et al 2001;Kö nig et al 2002). 1-Cys PRXs harbor a nuclear bipartite signal allowing targeting to the nucleus and/or the cytosol (Stacy et al 1999;Haslekas et al 2003) while type II PRXs are found in several subcellular compartments. Arabidopsis type II PRXs AtPRXIIB, AtPRXIIC, and AtPRXIID are in the cytosol, AtPRXIIE is chloroplastic, and AtPRXIIF is targeted to mitochondria (Bréhélin et al 2003;Finkemeier et al 2005).…”

ZRF1 Chromatin Regulators Have Polycomb Silencing and Independent Roles in Development

“…Consistently, the atzrf1a atzrf1b and atbmi1a atbmi1b mutants show derepression of ABI3, CRU1/CRA1, CRU3, CHO1/AIL5, and PER1. These seed developmental genes have been demonstrated to negatively regulate seed germination (Parcy et al, 1994;Haslekås et al, 2003;Yamagishi et al, 2009). The AtBMI1b and AtRING1a proteins interact physically with the plant-specific PHD domain proteins of the ALFIN1-like (AL) family (Molitor et al, 2014).…”

Peroxiredoxins in Plants and Cyanobacteria

“…Stacy et al (166) could lateron classify both genes pBS128 from Brome grass and B15C from barley as 1-CysPrx. Recombinant expression of At-1-CysPrx decreases sensitivity of E. coli cells to cumene hydroperoxide (55). Green fluorescent proteinfusions with At-1-CysPrx are targeted to the nucleus as well as the cytosol.…”