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The phytohormone gibberellin (GA) is a vital plant signaling molecule that regulates plant growth and defense against abiotic and biotic stresses. To date, the molecular mechanism of the plant responses to viral infection mediated by GA is still undetermined. DELLA is a repressor of GA signaling and is recognized by the F-box protein, a component of the SCFSLY1/GID2 complex. The recognized DELLA is degraded by the ubiquitin-26S proteasome, leading to the activation of GA signaling. Here, we report that ageratum leaf curl Sichuan virus (ALCScV)-infected N. benthamiana plants showed dwarfing symptoms and abnormal flower development. The infection by ALCScV significantly altered the expression of GA pathway-related genes and decreased the content of endogenous GA in N. benthamiana. Furthermore, ALCScV-encoded C4 protein interacts with the DELLA protein NbGAI and interferes with the interaction between NbGAI and NbGID2 to prevent the degradation of NbGAI, leading to inhibition of the GA signaling pathway. Silencing of NbGAI or exogenous GA3 treatment significantly reduces viral accumulation and disease symptoms in N. benthamiana plants. The same results were obtained from experiments with the C4 protein encoded by tobacco curly shoot virus (TbCSV). Therefore, we propose a novel mechanism by which geminivirus C4 proteins control viral infection and disease symptom development by interfering with the GA signaling pathway. Author summary: Gibberellins (GAs) are plant hormones essential for many developmental processes in plants. Plant virus infection can induce abnormal flower development and influence the GA pathway, resulting in plant dwarfing symptoms, but the underlying mechanisms are still not well described. Here, we demonstrate that the geminivirus-encoded C4 protein regulates the GA signaling pathway to promote viral accumulation and disease symptom development. By directly interacting with NbGAI, the C4 protein interferes with the interaction between NbGAI and NbGID2, which inhibits the degradation of NbGAI. As a result, the GA signaling pathway is blocked, and the infected plants display symptoms of typical dwarfing and delayed flowering. Our results reveal a novel mechanism by which geminivirus C4 proteins influence viral pathogenicity by interfering with the GA signaling pathway and provide new insights into the interaction between the virus and host. [ABSTRACT FROM AUTHOR]

This paper presents a method based on Current Hoop Model for the analysis and design of induction coilgun. The cylindrically symmetric armature is subdivided into concentric hoops with diverse rectangular cross-sections, in each of which the current is assumed to be uniformly distributed. An equivalent analytical model considering mutual coupling of coils and armature hoops is constructed for dynamic simulation of the coilgun. Based on this model, the self- and mutual-inductances of exciting winding and hoops are calculated by Neumann method. The circuit equations are solved coupled with the equation of motion of projectile by using the Treanor method to ensure the convergence. Comparison between the experimental results and the numerical results simulated by Finite Element method (FEM) shows the validity of the presented simulation method for coilgun. The optimization of a six-stage coilgun is achieved by employing the genetic algorithm (GA). [ABSTRACT FROM AUTHOR]