Multi-modal priming for plant stress resilience: Emerging agents and applications

Extreme weather events are taking a toll on global agriculture, slashing crop yields by nearly a quarter each year. This escalating volatility undermines food security, particularly as conventional protective measures struggle to keep up with the pace and complexity of environmental stressors. The limited scope of current plant priming strategies, which rely on a narrow set of conventional chemical elicitors, phytohormones, and basic hydro priming strategies, often lacks the flexibility to address multiple stress conditions simultaneously, highlighting an urgent call for the development of more robust and adaptable priming strategies and solutions. The current review fills this research-gap, and explores some lesser-known agents and well-established next-generation nano-based agents offering multi-layered protection by tapping into diverse yet synergistic biological pathways driving stress resilient agricultural practices. While arachidonic acids and synthetic analogues of ABA (abscisic acid) can recalibrate hormonal signalling, resulting in fine-tuned responses of plants under stress, SL/SL-mimics coordinate with other phytohormonal signalling cascades for effective modulation of root-shoot architectural dynamics for stress adaptation. Dual-release gastrotransmitter agents like NOSH-aspirin can release hydrogen sulfide and nitric oxide simultaneously, which are crucial gaseous signalling molecules involved in stress signalling and cellular resilience. Meanwhile, molecules like ebselen deliver localized antioxidant support, and ectoine, a naturally derived osmolyte, fortifies cell membranes against dehydration and salinity shocks. Adding another layer of nanomaterial-based priming, graphene oxide not only acts as a smart delivery vehicle for these agents but also confers protective properties of its own, whereas the intrinsic optical and ROS scavenging properties of carbon dots alongside their exceptional water dispersion and plant tissue penetration abilities make them desirable candidates in area of nanomaterial based screening of stress resilience in various plant species. Alongside these, an expanding library of small molecules is being engineered to intervene with surgical precision in plant metabolic pathways, targeting stress nodes without inhibiting growth. The immediate effectiveness as well as induction of long-lasting "stress memories" through epigenetic tuning and metabolomic reprogramming induced by such agents can train plants to remember and react faster to future threats, offering broader stress tolerance, reduced toxicity, and more targeted efficacy.