Potassium fluxes and reactive oxygen species production as potential indicators of salt tolerance in Cucumis sativus

Abstract

Salt stress, among other abiotic stresses, has a high impact on crop yield. Salt tolerance is a multifactorial trait that involves the ability of cells to retain K ions, regulate reactive O species (ROS) production, and synthesise new molecules to cope with osmotic stress. In the present work, two different cultivars of Cucumis sativus L. (cv. Parys, sensitive; cv. Polan, tolerant) were selected based on their germination capabilities under 100 mM NaCl. The capacity of these two cultivars to tolerate salt stress was analysed using several different physiological and genetic approaches. K+ fluxes from roots, as an immediate response to salinity, showed the higher ability of cv. Polan to maintain K+ compared with cv. Parys, according to the expression level of inward rectifying potassium channel 1 (AKT1). ROS production was also investigated in both cultivars and a higher basal ROS level was observed in cv. Polan than in cv. Parys. Concurrently, an increased basal level of respiratory burst oxidase homologue F (RBOHF) gene was also found, as well as a strong induction of the ethylene responsive factor 109 (ERF109) transcription factor after salt treatment in cv. Polan. Our data suggest that roots’ ability to retain K+, a higher level of RBOHF and a strong induction of ERF109 should all be considered important components for salt tolerance in C. sativus.

Melatonin improves rice salinity stress tolerance by NADPH oxidase‐dependent control of the plasma membrane K+ transporters and K+ homeostasis

“…These pharmacological and genetic results suggest that RBOH-mediated ROS acts as a downstream signal of melatonin to enhance K + retention in rice under salt stress. Consistent with this notion are previous reports that RBOH can improve salt stress tolerance by regulating K + homeostasis in several plant species (Huang et al, 2019;Lockhart, 2013;Ma et al, 2012;Redwan et al, 2016). Thus, melatonin enables initiation of NADPH-mediated transient ROS production without compromising intracellular K + homeostasis.…”

Physiological, biochemical, and antioxidant properties of two genotypes of Vicia faba grown under salinity stress

“…Salinity stress tolerance in plants is reportedly conferred by K + retention and Na + exclusion from the shoots (Shabala, 2017). Positive correlations between K + retention in plant tissues and salinity tolerance have been reported in wheat (Wu et al, 2015), alfalfa (Guo et al, 2016), cotton (Wang et al, 2016), mustard (Chakraborty et al, 2016), and cucumber (Redwan et al, 2016). Salt tolerant genotypes maintain high K + /Na + ratios under salinity stress; this has been reported by Wu et al, (2015) in barley and by Xiong et al, (2018) in melon.…”

HvAKT2 and HvHAK1 confer drought tolerance in barley through enhanced leaf mesophyll H+ homoeostasis

“…H 2 O 2 is an early response of K + deficiency and externally added H 2 O 2 was sufficient for the induction of the high-affinity K + uptake (Shin and Schachtman, 2004;Wang et al, 2017). Although there was no report on the correlation between AKT2 and HAK1 regulated K + homoeostasis and H 2 O 2 accumulation in plant drought tolerance, positive relationships between H 2 O 2 production and K + accumulation under salt stress were found for Arabidopsis, cucumber (Cucumis sativus) and pumpkin (Cucurbita moschata) (Huang et al, 2019;Ma et al, 2012;Redwan et al, 2016). For instance, it was demonstrated that higher salt tolerance in pumpkin is related to its higher K + uptake and H 2 O 2 accumulation in the root apex.…”