Exogenous Salicylic Acid Modulates the Response to Combined Salinity-Temperature Stress in Pepper Plants (Capsicum annuum L. var. Tamarin).

Ginés Otálora,Francisco Del Amor,Jacinta Collado-González,María Piñero,Josefa López-Marín

doi:10.3390/plants9121790

Ginés Otálora, Francisco Del Amor + Show 3 more

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https://doi.org/10.3390/plants9121790

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Abstract

Growers in the cultivated areas where the climate change threatens the agricultural productivity and livelihoods are aware that the current constraints for good quality water are being worsened by heatwaves. We studied the combination of salinity (60 mM NaCl) and heat shock stress (43 °C) in pepper plants (Capsicum annuum L. var. Tamarin) since this can affect physiological and biochemical processes distinctly when compared to separate effects. Moreover, the exogenous application of 0.5 mM salicylic acid (SA) was studied to determine its impacts and the SA-mediated processes that confer tolerance of the combined or stand-alone stresses. Plant growth, leaf Cl− and NO3− concentrations, carbohydrates, and polyamines were analyzed. Our results show that both salinity stress (SS) and heat stress (HS) reduced plant fresh weight, and SA only increased it for HS, with no effect for the combined stress (CS). While SA increased the concentration of Cl− for SS or CS, it had no effect on NO3−. The carbohydrates concentrations were, in general, increased by HS, and were decreased by CS, and for glucose and fructose, by SA. Additionally, when CS was imposed, SA significantly increased the spermine and spermidine concentrations. Thus, SA did not always alleviate the CS and the plant response to CS cannot be directly attributed to the full or partial sum of the individual responses to each stress.

Highlights

Global warming is increasing the number, intensity, and duration of abiotic stress combinations worldwide, which impair crop growth, yield, and product quality [1]
The fresh weight values recorded for control plants were reduced by 20.4% and 32.4% when salinity or heat stress, respectively, was imposed, but salinity did not reduce the growth of plants already exposed to heat stress
The spraying of salicylic acid (SA) boosted the fresh weight of non-stressed plants (20.3%) and of heat-stressed plants (39.6%); this effect was clearly diminished with salinity alone or with the combined stress

Summary

Introduction

Global warming is increasing the number, intensity, and duration of abiotic stress combinations worldwide, which impair crop growth, yield, and product quality [1]. It has been suggested that each abiotic stress combination requires new research as it should be studied as an entirely new stress [3] Increases in both air temperature and the salinity of irrigation waters will be two of the major constraints to human food production in the coming years. Salinity is a serious concern, being an increasing problem in agriculture because of the competition of good-quality water from industry and the progressive salinization of aquifers and other water resources, especially in arid and semiarid regions. This scarcity of good-quality water is dramatically accentuated by the rainfall alterations provoked by climate change. Extreme temperatures associated with prolonged heatwaves impact more than 10% of land surfaces [5]

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