A lentinan-loaded hydrogel with core-shell structure induces broad-spectrum resistance against plant virus by activating the expression of CML30

Control of plant virus disease largely depends on the induced plant defense achieved by the external application of synthetic chemical inducers with the ability to modify defense-signaling pathways. However, most of the molecular mechanisms underlying these inducers remain unknown. Here, we developed a lentinan-loaded hydrogel with the core-shell structure and discovered how it protects plant from different virus infections. The hydrogel was synthesized by adding a chitosan shell on the surface of the sodium alginate-calcium ion-lentinan (LNT) hydrogel (SL-gel) to form CSL-gel. CSL-gel exhibits the capacity of prolonging the stable-release of lentinan and promoting calcium ions release. Application of CSL-gel on the root of plants significantly promotes plant growth and development and induces broad-spectrum resistance against TMV, TuMV, PVX and TRV. Furthermore, we found that the sustained release of calcium ions from the CSL-gel triggers the high expression of cal-modulin-like protein 30 (CML30), and silencing of CML30 enhances the susceptibility of tobacco to TMV. Our findings provide evidence that the novel and synthetic CSL-gel with the sustainable release of LNT and calcium ion strongly inhibits the plant virus infection. This study uncovers a novel mode of action by which CSL-gel with the stable release of calcium ion triggers CML30 expression.