High atmospheric carbon dioxide-dependent alleviation of salt stress is linked to RESPIRATORY BURST OXIDASE 1 (RBOH1)-dependent H2O2 production in tomato (Solanum lycopersicum).

Changyu Yi,Kaiqian Yao,Huizi Li,Xiaojian Xia,Shuyu Cai,Jie Zhou,Jingquan Yu,Christine Helen Foyer,Yanhong Zhou,Kai Shi

doi:10.1093/jxb/erv435

Changyu Yi, Kaiqian Yao + Show 8 more

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https://doi.org/10.1093/jxb/erv435

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Abstract

Plants acclimate rapidly to stressful environmental conditions. Increasing atmospheric CO2 levels are predicted to influence tolerance to stresses such as soil salinity but the mechanisms are poorly understood. To resolve this issue, tomato (Solanum lycopersicum) plants were grown under ambient (380 μmol mol(-1)) or high (760 μmol mol(-1)) CO2 in the absence or presence of sodium chloride (100mM). The higher atmospheric CO2 level induced the expression of RESPIRATORY BURST OXIDASE 1 (SlRBOH1) and enhanced H2O2 accumulation in the vascular cells of roots, stems, leaf petioles, and the leaf apoplast. Plants grown with higher CO2 levels showed improved salt tolerance, together with decreased leaf transpiration rates and lower sodium concentrations in the xylem sap, vascular tissues, and leaves. Silencing SlRBOH1 abolished high CO2 -induced salt tolerance and increased leaf transpiration rates, as well as enhancing Na(+) accumulation in the plants. The higher atmospheric CO2 level increased the abundance of a subset of transcripts involved in Na(+) homeostasis in the controls but not in the SlRBOH1-silenced plants. It is concluded that high atmospheric CO2 concentrations increase salt stress tolerance in an apoplastic H2O2 dependent manner, by suppressing transpiration and hence Na(+) delivery from the roots to the shoots, leading to decreased leaf Na(+) accumulation.

Highlights

Crop productivity and food security are threatened by et al, 2012)
While biomass was reduced by growth in the presence of salt, the salt-induced reduction in biomass was Elevated CO2-induced salt stress tolerance | Page 5 of 14 significantly lower in plants grown with CO2 enrichment than under ambient CO2 conditions (Fig. 1A)
Stomatal conductance (Gs) values and transpiration rates (Tr) were lower in plants grown with CO2 enrichment than under ambient CO2 conditions, in the presence or the absence of salt stress (Supplementary Fig. S1)

Summary

Introduction

Crop productivity and food security are threatened by et al, 2012). atmospheric CO2 levels are likely to global climate change factors, such as projected temperature double by the end of this century (Solomon et al, 2007). Crop increases of more than 3.5 °C Due in part to rising sea levels and agricultural practices such as irrigation and fertilization. Greenhouse crops, which are often grown with elevated levels of CO2, can experience salinity because of frequent irrigation and fertilization, which are common practices in greenhouse agriculture. High atmospheric CO2 levels are likely to have a profound effect on oxidative signalling in plants, because of the suppression of photorespiration (Munne-Bosch et al, 2013). While many studies have focused either on plant responses to atmospheric CO2 enrichment or salt stress, there is a dearth of literature on plant responses to the combined effects of salinity and high CO2. High CO2 is known to induce salt tolerance (Yu et al, 2015) but the molecular and metabolic mechanisms that underpin this response are poorly understood

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