The Maize Sulfite Reductase Is Involved in Cold and Oxidative Stress Responses

Abstract

Sulfite reductase (SiR) functions in sulfate assimilation pathway. However, whether it is involved in stress response in crops is largely unknown. Here, the SiR ortholog from Zea mays (ZmSiR) was characterized. The recombinant ZmSiR protein was purified from E. coli. It exhibited sulfite-dependent activity and had strong affinity for sulfite. ZmSiR transcripts were markedly up-regulated by cold and methyl viologen (MV) treatments. Overexpression of ZmSiR complemented growth retardation phenotype of Arabidopsis atsir mutant. ZmSiR-overexpressing Arabidopsis plants were tolerant to severe SO2 stress and rescued the susceptible phenotype of the atsir. ZmSiR knock-down transgenic maize plants with 60% residual transcripts were more susceptible to cold or oxidative stress than wild-type. The severe damage phenotypes of the ZmSiR-compromised maize plants were accompanied by increases of sulfite and H2O2 accumulations, but less amounts of GSH. The qPCR analysis revealed that there was significantly altered expression of several key sulfur metabolism-related genes in ZmSiR-impaired maize lines under cold or MV stress. Particularly, ZmAPR2 expression was significantly elevated, suggesting that toxic sulfite accumulation in ZmSiR-impaired plants could be attributable to the reduced SiR coupled to increased ZmAPR2 expression. Together, our results indicate that ZmSiR is involved in cold and oxidative stress tolerance possibly by modulating sulfite reduction, GSH-dependent H2O2 scavenging, and sulfur-metabolism related gene expression. ZmSiR could be exploited for engineering environmental stress-tolerant varieties in molecular breeding of maize.

Regulation of Hydrogen Sulfide Metabolism by Nitric Oxide Inhibitors and the Quality of Peaches during Cold Storage

“…In plants, SiR, which functions in the sulfate assimilation pathway, can reduce sulfite to produce H 2 S, with ferredoxin as an electron donor. It is involved in cold and oxidative stress tolerance, possibly due to its modulation of sulfite reduction and GSH-dependent H 2 O 2 scavenging [54]. Exogenous NO significantly promoted the decrease of SiR activity in peaches, which could contribute to the low content of H 2 S in peaches treated with exogenous NO during cold storage.…”

A natural single‐nucleotide polymorphism variant in sulfite reductase influences sulfur assimilation in maize

“…The gene ZmSiR ( Zm00001d038625 ) exists as a single copy in the genome of maize (Xia et al ., 2018). To unravel the genetic architecture of the natural variation in the ZmSiR protein abundance, we performed GWAS in a maize association population consisting of 70 inbred lines (Yang et al ., 2011).…”

“…It is also reported in Arabidopsis that the variation in leaf sulfate content is regulated by an ATPS1 expression‐level polymorphism (Koprivova et al ., 2013). As a key step in the reductive sulfur assimilation pathway, the activity of SiR has been reported to be critical for plant growth and development in various plant species, including Arabidopsis (Khan et al ., 2010), tomato (Yarmolinsky et al ., 2014), and maize (Xia et al ., 2018). Because these studies used either transfer DNA mutagenesis or RNA interference to impair SiR transcription, we still lack an understanding about how naturally occurring genetic variations impact gene expression of SiR in natural plant populations.…”

“…For instance, it is known that GSH contributes to the protection of maize plants from chilling injury or cold hardening at low temperature (Kocsy et al ., 2001). Related to this, a recent study indicates that ZmSiR is involved in cold and other oxidative stress tolerance (Xia et al ., 2018). Meanwhile, sulfate was primarily assimilated in maize leaf bundle sheath and mesophyll cell and delivered to filling seeds (Kopriva & Koprivova, 2005; Xiang et al ., 2018).…”

Redox regulation of enzymes involved in sulfate assimilation and in the synthesis of sulfur-containing amino acids and glutathione in plants

“…In order to protect cells against sulfite toxicity, SIR expression is rapidly upregulated in Arabidopsis and tomato in response to higher sulfite content, and accordingly SIR activity increases ( Yarmolinsky et al, 2013 ). SIR transcripts are also upregulated after cold stress and methyl viologen treatment in maize ( Xia et al, 2018 ). Using proteomic approaches, SIR has been identified as a TRX target in wheat seeds ( Wong et al, 2004 ) and in Synechocystis ( Lindahl and Florencio, 2003 ).…”