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

Antonio Sánchez-Guerrero,Miquel Nadal,Igor Florez-Sarasa,Ana Jiménez,José G Vallarino,Francisca Sevilla,Miquel Ribas-Carbó,Alisdair R Fernie,Jaume Flexas,Sabrina De Brasi-Velasco

doi:10.3390/ijms22031063

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.

Highlights

Soil and water salinity are major threat to global food security since it is one of the most decisive environmental stresses affecting plant growth and productivity
Rosette diameter was similar in all genotypes (Figure 1A), the total leaf area was lower in the KO1 mutant than in wild type (WT) and KO2 plants (Figure 1B) and KO1 line displayed a higher number of leaves (Figure 1C)
Some differences have been previously reported between both KO lines in differfect the stress response and recent studies on KO Attrxo1 mutants grown in saent parameters, of growth and antioxidant components, metabolites, oxidative linity conditions have revealed a rolein for thistoTRXo1 indrought responding to this adverse stress parameters response salinity and Differences amongsitualines are not visualized as commented above, but the measurement of a high number of samples have shown some significant differences in growth parameters as leaf area/plant between KO1 and KO2 lines and in the number of leaves between WT and KO1 plants

Summary

Introduction

Soil and water salinity are major threat to global food security since it is one of the most decisive environmental stresses affecting plant growth and productivity. The response to salinity and other environmental stresses is frequently associated with an increase of reactive oxygen and nitrogen species (ROS, RNS) which can alter both, metabolite levels and cysteine thiols of proteins. These redox changes are an important and integral part in plant signaling elicited by specific stresses as well as in response to a change in energy balance [5,6]. Plant mitochondria play an important role in the salinity response by modifying the tricarboxylic acid (TCA) cycle, the electron transport pathways activity and the transport of metabolites across the inner mitochondrial membranes [9,10].

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Discussion

Conclusion