**1. Introduction**

Plants cannot avoid the multiple abiotic stresses to which they are constantly exposed because of their sessile nature. Stresses like salinity, drought, cold and heat greatly hinder the growth and productivity of plants. Among those, soil salinity significantly affects crop output and growth all over the world [1]. It is estimated that by 2050, roughly 20% of agricultural land will be unproductive due to soil salinization, which will affect nearly 50% of agricultural land [2]. Salt stress occurs when there is too much Na+ in the soil solution, preventing plants from receiving water and nutrients from the soil. Na+ accumulation is harmful because it causes osmotic and ionic stresses that promote the formation of ROS, alter plant metabolism, and upset the balance of ions in the environment [3].

Based on their capacity to flourish in salty conditions, plants are divided into two main groups called glycophytes and halophytes. Since most cultivated plants are glycophytes, they cannot withstand salty environments with concentrations of more than 100 mM NaCl. In the case of cereals, rice (*Oryza sativa*) is classified as the least tolerant species, followed by durum wheat (*Triticum durum*), common wheat (*Triticum aestivum*), maize (*Zea mays*) and barley (*Hordeum vulgare*) which is considered as the most tolerant species [4].

A proper hormonal balance is required in plants in order to limit the potential negative impacts of environmental variables. Most phytohormones are know to play a major role in controlling plant growth and development as well as stress responses [5–8]. Thanks to their extensive range of functions and complex interplay, auxin and brassinosteroids (BRs) are considered as two of the phytohormones that hold the most promise for tailoring abiotic stress tolerance in crop plants [9, 10]. Many auxin-responsive genes have been demonstrated to be synergistically regulated by the interaction between BRs and auxin pathways [11]. Furthermore, through separate processes, auxin and BRs can stimulate root development and increase cell expansion [12]. This chapter attempts to offer new insights into our understanding of how auxin, BR and their interactions can support plants' ability to balance growth and salt stress tolerance (**Figure 1**).
