Understanding the phytohormones biosynthetic pathways for developing engineered environmental stress-tolerant crops

Abstract

Plants are significantly subject of diverse environmental stresses. Abiotic stresses are mainly due to nonliving environmental factors such as drought, heat, cold, and salinity, whereas biotic stresses are mainly caused by other living organisms in the surrounding environment such as bacteria, fungi, viruses, nematodes, and insects. A long series of investigations has now developed beyond the doubt that major phytohormones such as auxins, cytokinins (CK), gibberellins (GAs), abscisic acid (ABA), ethylene (ET), brassinosteroids (BRs), salicylic acid (SA), jasmonates (JAs), and strigolactones and their biosynthetic and signaling pathways play central roles in integrating and coordinating the whole plant stress responses. Understanding the mechanisms and the biosynthetic pathways of different phytohormones that can enhance plant stress tolerance could lead to developing an environmental stress-tolerant crop through engineering the target phytohormones biosynthetic pathways. This chapter provides an overview on the relationships between different types of phytohormones and plant response to environmental stresses. We emphasize the significant contribution of transgenerational effects (maternal and epigenetic) on phytohormones biosynthesis. Additionally, the molecular mechanisms and regulation of phytohormones biosynthetic pathways are discussed in details. Omics and metabolic engineering prospective for developing environmental stress-tolerant crops are also highlighted.