Exogenous Copper Application for the Elemental Defense of Rice Plants against Rice Leaffolder (Cnaphalocrocis medinalis)

Degradable mesoporous organosilicon nanoparticles coated with chitosan-Cu2+ complexes with dual stimulus-response for efficient prochloraz delivery

Accurate pesticide application enhances efficiency, reduces usage and minimizes environmental risks. This study employed amino-functionalized degradable mesoporous organosilicon nanoparticles (DMON-N) as a carrier, with chitosan (CS) acting as a capping agent. Chemical cross-linking of CS with Cu2+ through chelation promotes the formation of Cu2+-CS complexes. A pH/redox dual-responsive prochloraz (PRO) delivery system (Cu-CS@PRO-DMON, CCPD) was constructed and evaluated for its potential application in controlling rice sheath blight. The successful preparation of CCPD was confirmed through a series of physicochemical characterizations. The findings demonstrated that CCPD exhibited a high PRO loading capacity (29.09 %) and that PRO could be released from CCPD for an extended duration (up to 144 h) under the influence of acidity and glutathione promotion. Furthermore, CCPD demonstrated excellent wettability (measured contact angle: 63.52 ± 0.42°), adhesion (23.83 ± 2.59 mg/cm2) and resistance to rainfall washout on rice leaves. CCPD demonstrated superior antimicrobial efficacy to prochloraz technical (PRO TC) material and prochloraz emulsion in water (PRO EW). The biosafety assessment revealed that CCPD exhibited minimal acute toxicity to zebrafish, no discernible toxicological effects on human bronchial epithelial cells and no notable impact on rice.

Advances in the Involvement of Metals and Metalloids in Plant Defense Response to External Stress

Plants, as sessile organisms, uptake nutrients from the soil. Throughout their whole life cycle, they confront various external biotic and abiotic threats, encompassing harmful element toxicity, pathogen infection, and herbivore attack, posing risks to plant growth and production. Plants have evolved multifaceted mechanisms to cope with exogenous stress. The element defense hypothesis (EDH) theory elucidates that plants employ elements within their tissues to withstand various natural enemies. Notably, essential and non-essential trace metals and metalloids have been identified as active participants in plant defense mechanisms, especially in nanoparticle form. In this review, we compiled and synthetized recent advancements and robust evidence regarding the involvement of trace metals and metalloids in plant element defense against external stresses that include biotic stressors (such as drought, salinity, and heavy metal toxicity) and abiotic environmental stressors (such as pathogen invasion and herbivore attack). We discuss the mechanisms underlying the metals and metalloids involved in plant defense enhancement from physiological, biochemical, and molecular perspectives. By consolidating this information, this review enhances our understanding of how metals and metalloids contribute to plant element defense. Drawing on the current advances in plant elemental defense, we propose an application prospect of metals and metalloids in agricultural products to solve current issues, including soil pollution and production, for the sustainable development of agriculture. Although the studies focused on plant elemental defense have advanced, the precise mechanism under the plant defense response still needs further investigation.