Exploring intermetallic synergy has allowed a series of alloy nanoparticles with prominent chemical–physical properties to be produced. However, precise alloying based on a maintained template has long been a challenging pursuit, and little has been achieved for manipulation at the atomic level. Here, a nanosystem based on M29(S-Adm)18(PPh3)4 (where S-Adm is the adamantane mercaptan and M is Ag/Cu/Au/Pt/Pd) has been established, which leads to the atomically precise operation on each site in this M29 template. Specifically, a library of 21 species of nanoclusters ranging from monometallic to tetrametallic constitutions has been successfully prepared step by step with in situ synthesis, target metal-exchange, and forced metal-exchange methods. More importantly, owing to the monodispersity of each nanocluster in this M29 library, the synergetic effects on the optical properties and stability have been mapped out. This nanocluster methodology not only provides fundamental principles to produce alloy nanoclusters with multimetallic compositions and monodispersed dopants but also provides an intriguing nanomodel that enables us to grasp the intermetallic synergy at the atomic level.

Karrikins are reported to stimulate seed germination, regulate seedling growth, and increase the seedling vigor in abiotic stress conditions in plants. Nevertheless, how karrikins alleviate abiotic stress remains largely elusive. In this study, we found that karrikin (KAR 1 ) could significantly alleviate both drought and salt stress in the important oil plant Sapium sebiferum. KAR 1 supplementation in growth medium at a nanomolar (nM) concentration was enough to recover seed germination under salt and osmotic stress conditions. One nanomolar of KAR 1 improved seedling biomass, increased the taproot length, and increased the number of lateral roots under abiotic stresses, suggesting that KAR 1 is a potent alleviator of abiotic stresses in plants. Under abiotic stresses, KAR 1 -treated seedlings had a higher activity of the key antioxidative enzymes, such as superoxide dismutase, peroxidase, catalase, and ascorbate peroxidase, in comparison with the control, which leads to a lower level of hydrogen peroxide, malondialdehyde, and electrolyte leakage. Moreover, the metabolome analysis showed that KAR 1 treatment significantly increased the level of organic acids and amino acids, which played important roles in redox homeostasis under stresses, suggesting that karrikins might alleviate abiotic stresses via the regulation of redox homeostasis. Under abiotic stresses, applications of karrikins did not increase the endogenous abscisic acid level but altered the expression of several ABA signaling genes, such as SNF1-RELATED PROTEIN KINASE2.3, SNF1-RELATED PROTEIN KINASE2.6, ABI3, and ABI5, suggesting potential interactions between karrikins and ABA signaling in the stress responses. Conclusively, we not only provided the physiological and molecular evidence to clarify the mechanism of karrikins in the regulation of stress adaptation in S. sebiferum but also showed the potential value of karrikins in agricultural practices, which will lay a foundation for further studies about the role of karrikins in abiotic stress alleviation in plants.

The concept of “graft-onto” has been exploited to facilitate nanocluster growth from Pt1Ag28 to Pt1Ag31.