Decreased Levels of Thioredoxin o1 Influences Stomatal Development and Aperture but Not Photosynthesis under Non-Stress and Saline Conditions

Abstract

Salinity has a negative impact on plant growth, with photosynthesis being downregulated partially due to osmotic effect and enhanced cellular oxidation. Redox signaling contributes to the plant response playing thioredoxins (TRXs) a central role. In this work we explore the potential contribution of Arabidopsis TRXo1 to the photosynthetic response under salinity analyzing Arabidopsis wild-type (WT) and two Attrxo1 mutant lines in their growth under short photoperiod and higher light intensity than previous reported works. Stomatal development and apertures and the antioxidant, hormonal and metabolic acclimation are also analyzed. In control conditions mutant plants displayed less and larger developed stomata and higher pore size which could underlie their higher stomatal conductance, without being affected in other photosynthetic parameters. Under salinity, all genotypes displayed a general decrease in photosynthesis and the oxidative status in the Attrxo1 mutant lines was altered, with higher levels of H2O2 and NO but also higher ascorbate/glutathione (ASC/GSH) redox states than WT plants. Finally, sugar changes and increases in abscisic acid (ABA) and NO may be involved in the observed higher stomatal response of the TRXo1-altered plants. Therefore, the lack of AtTRXo1 affected stomata development and opening and the mutants modulate their antioxidant, metabolic and hormonal responses to optimize their adaptation to salinity.

Thioredoxin TRXo1 is involved in ABA perception via PYR1 redox regulation

“…In this sense, other redox post-translational modifications on specific amino acid residues in target proteins apart from Cys oxidation, such as S-nitrosylation, S-glutahionylation, persulfidation or Tyr nitration, are emerging as key regulators of signal transduction, allowing cell response under an imbalance of redox homeostasis. In this way, regulated proteins involved in different metabolic pathways are able to sense and transmit the imbalance occurring in response to biotic and abiotic stresses [ 15 , 21 , [56] , [57] , [58] ]. Related to ROS-induced modifications, a mild oxidative stress causes the oxidation of Cys residues in proteins to generate sulfenic forms or disulfide bridges, both reduced to –SH by different cellular reductants.…”

The emerging key role of reactive sulfur species in abiotic stress tolerance in plants

“…Overexpression of AtTrx‐h2 in Brassica napus promotes salt resistance (Ji et al, 2020), and overexpression of GhTRX134 in Arabidopsis likewise improves plant resistance to drought, salt, and oxidative stress (Elasad et al, 2020). Attrxo1 mutants also exhibit better adaptation to salt stress due to the modulation of antioxidant, metabolic, and hormonal responses (Sánchez‐Guerrero et al, 2021).…”

Genome‐wide analysis and transcriptional regulation of the typical and atypical thioredoxins in Arabidopsis thaliana

“…Further, At-trx-o1 T-DNA mutants have been used to unravel the regulatory mechanisms by which the mitochondrial TRX system regulates TCA cycle enzymes, photorespiration and mitochondrial electron transport pathways in vivo [57,58]. The lack of TRX-o1 impacts stomata development and aperture but not photosynthesis [59].…”

“…Salt stress provoked an accumulation of PsTRX-f, PsTRX-m1 and PsTRX-o1 transcripts [100,101]. Decreased amounts of AtTRX-o1 influence stomatal development and aperture under saline growth conditions [59]. Salinity induces an increase of TRX-h at transcriptional and post-transcriptional levels during germination and early seedling growth of wheat [102].…”