Cross-tolerance to abiotic stresses in halophytes: application for phytoremediation of organic pollutants

Abstract

Halopytes are plants able to tolerate high salt concentrations but no clear definition was retained for them. In literature, there are more studies that showed salt-enhanced tolerance to other abiotic stresses compared to investigations that found enhanced salt tolerance by other abiotic stresses in halophytes. The phenomenon by which a plant resistance to a stress induces resistance to another is referred to as cross-tolerance. In this work, we reviewed cross-tolerance in halophytes at the physiological, biochemical, and molecular levels. A special attention was accorded to the cross-tolerance between salinity and organic pollutants that could allow halophytes a higher potential of xenobiotic phytoremediation in comparison with glycophytes.

Priming-Mediated Tolerance to Biotic and Abiotic Stresses in Halophytes

“…Further, it improved resistance to drought and heavy metals in Sesuvium portulacastrum. Under low-to-moderate salinity conditions, salt priming was capable of improving salt tolerance in Distichlis spicata (Shiri et al 2015b). Priming is thought to improve the resistance of plants to abiotic stresses through the phenomenon of cross-tolerance.…”

“…Priming is thought to improve the resistance of plants to abiotic stresses through the phenomenon of cross-tolerance. This phenomenon is thought to happen due to oxidative stress tolerance since most of the injuries in plants are associated with oxidative damage at the cellular level (Shiri et al 2015b).…”

“…In our lab (unpublished study), we performed the first ever trial in halophytes, indicating that salt priming was capable of improving tolerance of C. maritima to pathogen stress of Alternaria alternata, whereby the photosynthetic metabolism was enhanced (Sghaier-Hammami et al 2020, unpublished data). This increase in the photosynthetic apparatus functioning may be explained by the presence of the phenomenon of cross-tolerance which enhanced the abundance of the protective proteins involved in photosynthesis activation and protein biosynthesis (Shiri et al 2015b). Hence, salt priming resulted in an improvement of defense against pathogen-induced oxidative stress (Sghaier-Hammami et al 2020; unpublished data).…”

“…These two systems are known to be implicated in the protection of the plant cells against ROS damage. Antioxidant enzymes include catalase (CAT), ascorbate peroxidase (APX), guaiacol peroxidase (GPOD), glutathione S-transferase (GST), GR, POX, GPX, SOD, and nonenzymatic antioxidants, like ascorbic acid (AsA), GSH, carotenoids, and tocopherols, among others, which work together to tightly control the level of ROS required for plant growth and development (Chen and Arora 2013;Hossain et al 2015;Shiri et al 2015b;Hossain et al 2018).…”

“…The simultaneous contamination of soil by high concentrations of soluble salts and heavy metals at the global level imposes serious threat to the human health and requires urgent solutions. Halophytes are very important plants in this regard since they can bear high soil salinity, alkalinity, and metal toxicities and they are costeffective (Shiri et al 2015b). Thus, they have a very high potential to desalinate and restore saline soils via phytoremediation besides wetland restoration.…”