As global climates shift, plants are increasingly exposed to biotic and abiotic stresses that adversely affect their growth and development, ultimately reducing agricultural productivity. To counter these stresses, plants produce secondary metabolites (SMs), which are critical biochemical and essential compounds that serve as primary defense mechanisms. These diverse compounds, such as alkaloids, flavonoids, phenolic compounds, and nitrogen/sulfur-containing compounds, act as natural protectants against herbivores, pathogens, and oxidative stress. Despite the well-documented protective roles of SMs, the precise mechanisms by which environmental factors modulate their accumulation under different stress conditions are not fully understood. This review provides comprehensive insights into the recent advances in understanding the functions of SMs in plant defense against abiotic and biotic stresses, emphasizing their regulatory networks and biosynthetic pathways. Furthermore, we explored the unique contributions of individual SM classes to stress responses while integrating the findings across the entire spectrum of SM diversity, providing a comprehensive understanding of their roles in plant resilience under multiple stress conditions. Finally, we highlight the emerging strategies for harnessing SMs to improve crop resilience through genetic engineering and present novel solutions to enhance agricultural sustainability in a changing climate.

Both biotic and abiotic stresses adversely affect plant growth and development, ultimately reducing agricultural productivity. Secondary metabolites (SMs) are essential compounds that contribute to plant survival by facilitating interactions with the environment. In response to both abiotic and biotic stresses, plants synthesize and accumulate SMs, which in turn trigger signaling pathways that lead to post-transcriptional modifications within plant cells. These changes activate a series of defense mechanisms that enhance the plant's resilience and adaptation to stress. SMs are instrumental in ensuring plant survival under challenging conditions by modulating the plant's defense systems to cope with environmental threats. Beyond their role in stress tolerance, SMs are also bioactive compounds with significant economic and health value. In this review, we explore the functions of various SMs, such as alkaloids, flavonoids, and phenolic acids in defense against abiotic and biotis stresses. Additionally, we discuss the potential of harnessing SMs in the genetic improvement of crop stress tolerance, highlighting their roles in advancing agricultural sustainability.

The rhizosphere plays a crucial role in plant growth and resilience to biotic and abiotic stresses, highlighting the complex communication between plants and their dynamic rhizosphere environment. Plants produce a wide range of signaling molecules that facilitate communication with various rhizosphere factors, yet our understanding of these mechanisms remains elusive. In addition to protein‐coding genes, increasing evidence underscores the critical role of microRNAs (miRNAs), a class of non‐coding single‐stranded RNA molecules, in regulating plant growth, development, and responses to rhizosphere stresses under diverse biotic and abiotic factors. In this review, we explore the crosstalk between miRNAs and their target mRNAs, which influence the development of key plant structures shaped by the belowground environment. Moving forward, more focused studies are needed to clarify the functions and expression patterns of miRNAs, to uncover the common regulatory mechanisms that mediate plant tolerance to rhizosphere dynamics. Beyond that, we propose that using artificial miRNAs and manipulating the expression of miRNAs and their targets through overexpression or knockout/knockdown approaches could effectively investigate their roles in plant responses to rhizosphere stresses, offering significant potential for advancing crop engineering.

The authors would like to make the following correction to their published paper