Multiple antiviral immunities were developed to defend against viral infection in hosts. RNA interference (RNAi)-based antiviral innate immunity is evolutionarily conserved in eukaryotes and plays a vital role against all types of viruses. During the arms race between the host and virus, many viruses evolve viral suppressors of RNA silencing (VSRs) to inhibit antiviral innate immunity. Here, we reviewed the mechanism at different stages in RNAi-based antiviral innate immunity in plants and the counteractions of various VSRs, mainly upon infection of RNA viruses in model plant Arabidopsis. Some critical challenges in the field were also proposed, and we think that further elucidating conserved antiviral innate immunity may convey a broad spectrum of antiviral strategies to prevent viral diseases in the future.

Transport inhibitor response 1/auxin signaling f-box proteins (TIR1/AFBs) play important roles in the process of plant growth and development as auxin receptors. To date, no information has been available about the characteristics of the TIR1/AFB gene family in Brassica juncea var. tumida. In this study, 18 TIR1/AFB genes were identified and could be clustered into six groups. The genes are located in 11 of 18 chromosomes in the genome of B. juncea var. tumida, and similar gene structures are found for each of those genes. Several cis-elements related to plant response to phytohormones, biotic stresses, and abiotic stresses are found in the promoter of BjuTIR1/AFB genes. The results of qPCR analysis show that most genes have differential patterns of expression among six tissues, with the expression levels of some of the genes repressed by salt stress treatment. Some of the genes are also responsive to pathogen Plasmodiophora brassicae treatment. This study provides valuable information for further studies as to the role of BjuTIR1/AFB genes in the regulation of plant growth, development, and response to abiotic stress.

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Salicylic acid (SA) is considered to be an endogenous signal molecule in plants, and it is related to many resistances in plants. In Arabidopsis, Non-expressor of pathogenesis-related gene1 (NPR1) mediates the expression of pathogenesis-related genes (PRs) and systemic acquired resistance (SAR) induced by SA. NPR1 is a key factor in SA signaling pathway, and the research shows that NPR1, NPR3 and NPR4 play a key role in SA mediated plant disease resistance. In this review, the interaction between NPR and transcription factors is discussed, and we also describe the progress of NPR in SA mediated SAR signal transduction pathway, likewise, we introduce the relationship between NPR1 and its paralogues NPR3/NPR4. This paper analyzes the research prospect of NPR as the intersection of multiple signal paths.

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