**1. Introduction**

Phytohormones are regulatory compounds produced in low concentrations and serve as chemical messengers to regulate various plant physiological and developmental processes. They also play essential roles in signal transduction pathways during stress response and regulate internal and external stimuli [1]. Phytohormones comprise five main groups, namely auxins (IAAs), cytokinins (CKs), abscisic acid (ABA), gibberellins (GAs) and ethylene (ET). Salicylates (SAs), jasmonates (JAs), brassinosteroids (BRs), strigolactones (SLs), polyamines, and some peptides represent new families of phytohormones.

Hormone actions form a signaling network and regulate various systems in plants. The interacting actions among hormone signal transduction cascades are called crosstalk [2, 3]. Phytohormones interact by activating a phosphorylation cascade or a common second mes‐ senger. Furthermore, several phytohormones interact together, forming a defense network against environmental stresses such as JA, SA, and ABA which play a crucial role in regulat‐ ing signaling pathways [3]. Understanding the crosstalk between these phytohormones and defense signaling pathways helps reveal new important targets for developing host resistance mechanisms [3, 4]. Here, the current work presents an overview and discusses recent pro‐ gresses of phytohormone roles and their crosstalk in plant development and stress tolerance.

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