Impact of SO₂ on Arabidopsis thaliana transcriptome in wildtype and sulfite oxidase knockout plants analyzed by RNA deep sequencing

Abstract

SummaryHigh concentrations of sulfur dioxide (SO 2 ) as an air pollutant, and its derivative sulfite, cause abiotic stress that can lead to cell death. It is currently unknown to what extent plant fumigation triggers specific transcriptional responses.To address this question, and to test the hypothesis that sulfite oxidase (SO) is acting in SO 2 detoxification, we compared Arabidopsis wildtype (WT) and SO knockout lines (SO-KO) facing the impact of 600 nl l À1 SO 2 , using RNAseq to quantify absolute transcript abundances. These transcriptome data were correlated to sulfur metabolism-related enzyme activities and metabolites obtained from identical samples in a previous study. SO-KO plants exhibited remarkable and broad regulative responses at the mRNA level, especially in transcripts related to sulfur metabolism enzymes, but also in those related to stress response and senescence. Focusing on SO regulation, no alterations were detectable in the WT, whereas in SO-KO plants we found up-regulation of two splice variants of the SO gene, although this gene is not functional in this line.Our data provide evidence for the highly specific coregulation between SO and sulfur-related enzymes like APS reductase, and suggest two novel candidates for involvement in SO 2 detoxification: an apoplastic peroxidase, and defensins as putative cysteine mass storages.

Impairment in Sulfite Reductase Leads to Early Leaf Senescence in Tomato Plants

“…Moreover, tomato and Arabidopsis RNA interference mutants lacking SO activity still exhibited significant residual sulfite oxidation (Eilers et al, 2001;Brychkova et al, 2007). The non-SO oxidation of sulfite was suggested to be initiated by ROS (Pfanz and Oppmann, 1991;Miszalski and Ziegler, 1992;Brychkova et al, 2012a;Hamisch et al, 2012). The decreased level of hydrogen peroxide, which was detected in the upper young leaves of SiR-impaired plants, could be a result of direct oxidation of sulfite to sulfate by hydrogen peroxide (Hänsch et al, 2006).…”

The mechanism of SO2‐induced stomatal closure differs from O3 and CO2 responses and is mediated by nonapoptotic cell death in guard cells

“…Taylor () proposed that plants obtained resistance to gaseous pollutants via “stress tolerance” and “stress avoidance” mechanisms, of which the first one involved capacity of plants to tolerate, assimilate, or buffer the harmful pollutant derivatives and the second mechanism involved the closing of stomata to avert pollutant absorption. Transcriptome analyses have disclosed the SO 2 detoxification process in plants, involving oxidative pathway in the peroxisomes (sulfite oxidase) and also plastid sulfur assimilation pathway localized in the chloroplasts (Brychkova et al, ; Considine & Foyer, ; Hamisch et al, ; Randewig et al, ). These findings explain the metabolic changes that take place in plant tolerance to nonphytotoxic levels of SO 2 .…”

“…Transcriptome analyses have disclosed the SO 2 detoxification process in plants, involving oxidative pathway in the peroxisomes (sulfite oxidase) and also plastid sulfur assimilation pathway localized in the chloroplasts (Brychkova et al, 2007;Considine & Foyer, 2015;Hamisch et al, 2012;Randewig et al, 2012). These findings explain the metabolic changes that take place in plant tolerance to nonphytotoxic levels of SO 2 .…”

Is white clover able to switch to atmospheric sulphur sources when sulphate availability decreases?

“…Studies with legumes have shown that phytotoxic effects of H 2 S and SO 2 are highly dependent on the species considered (Thomas et al, 1943;Maas et al, 1987). Toxicity of S gases also depends on atmospheric concentrations and physiological and environmental factors (Maas et al, 1987;De Kok et al, 2007;Hamisch et al, 2012). Studies with various plant species including legumes such as Trifolium pratense, Glycine max, and Phaseolus vulgaris have shown that SO 2 fumigation results in an increase in sulphate contents (Maas et al, 1987).…”