ROS scavenging and ion homeostasis is required for the adaptation of halophyte Karelinia caspia to high salinity

Abstract

The halophyte Karelinia caspia has not only fodder and medical value but also can remediate saline-alkali soils. Our previous study showed that salt-secreting by salt glands is one of main adaptive strategies of K. caspia under high salinity. However, ROS scavenging, ion homeostasis, and photosynthetic characteristics responses to high salinity remain unclear in K. caspia. Here, physio-biochemical responses and gene expression associated with ROS scavenging and ions transport were tested in K. caspia subjected to 100–400 mM NaCl for 7 days. Results showed that both antioxidant enzymes (SOD, APX) activities and non-enzymatic antioxidants (chlorogenic acid, α-tocopherol, flavonoids, polyamines) contents were significantly enhanced, accompanied by up-regulating the related enzyme and non-enzymatic antioxidant synthesis gene (KcCu/Zn-SOD, KcAPX6, KcHCT, KcHPT1, Kcγ-TMT, KcF3H, KcSAMS and KcSMS) expression with increasing concentrations of NaCl. These responses are beneficial for removing excess ROS to maintain a stable level of H2O2 and O2− without lipid peroxidation in the K. caspia response to high salt. Meanwhile, up-regulating expression of KcSOS1/2/3, KcNHX1, and KcAVP was linked to Na+ compartmentalization into vacuoles or excretion through salt glands in K. caspia. Notably, salt can improve the function of PSII that facilitate net photosynthetic rates, which is helpful to growing normally in high saline. Overall, the findings suggested that ROS scavenging systems and Na+/K+ transport synergistically contributed to redox equilibrium, ion homeostasis, and the enhancement of PSII function, thereby conferring high salt tolerance.

Characterization of HAK protein family in Casuarina equisetifolia and the positive regulatory role of CeqHAK6 and CeqHAK11 genes in response to salt tolerance

“…An earlier study by Li et al (2022) revealed that high salt tolerance was conferred by the synergistic contribution of ROS scavenging mechanisms and Na + /K + transport to redox balance and ion homeostasis. Overexpression of CeqHAK6 and CeqHAK11 increased the K + /Na + ratio and antioxidant enzyme activity of plants, which in turn reduced the accumulation of malondialdehyde, cations and H 2 O 2 due to membrane peroxidation, and finally achieved the purpose of protecting membrane structure and alleviating the damage caused by salt stress to the plants.…”

Metabolomics analysis unveils important changes involved in the salt tolerance of Salicornia europaea

“…When plants are exposed to a saline environment, ROS overgeneration disrupts the balance between ROS production and scavenging, inducing the oxidative damage of cells (Hao et al, 2021). Halophytes evolve a multifaceted antioxidant defense network to reduce ROS overgeneration under abiotic stress (Sirin and Aslım, 2019;Li et al, 2022). The phenylpropanoid pathway involves the biogenesis of diverse phenolic polymers, such as flavonoids and phenolic acids, which play important roles of ROS scavenging in plant defense against abiotic stresses (Liu et al, 2020;Li et al, 2021a).…”

NADPH oxidase-mediated reactive oxygen species, antioxidant isozymes, and redox homeostasis regulate salt sensitivity in maize genotypes

“…To produce salt-tolerant crops, we need to change our perspective and focus on traits that were ignored during the domestication of staple crops. These traits include keeping redox balance and signaling ROS mechanisms effectively, which are common in salt-tolerant plants [ 28 ].…”