The role of tissue succulence in plant salt tolerance: an overview

Soil salinity seriously restricts agricultural production. Halophytes adapt to saline environments through several strategies, including leaf or stem succulence. Succulence is associated with the increase in cell size or leaf thickness and high water content per unit of surface area, allowing salts to be diluted within the succulent leaves or stems. The proposed mechanisms of NaCl-induced plant tissue succulence include acidification and subsequent induction of cell wall elasticity, increased water uptake, cell turgor pressure, Na+ partitioning in vacuoles, abundance of plasma membrane aquaporins, cell wall formation and extensibility, as well as up-regulation of certain genes (e.g., XTH and CEB1) that control cell expansion and cell wall modification. However, the information on the mechanism of succulence activated by salinity is limited. In this paper, the possible mechanism of salinity-induced succulence, and the role of succulence in plant salt tolerance, are discussed. Understanding the mechanisms that activate succulence in halophytes opens up new opportunities for plant breeding to increase salt tolerance and improve crop productivity in saline soils.