Transcriptome reprogramming in the shoot apical meristem of CymRSV‐infected Nicotiana benthamiana plants associates with viral exclusion and the lack of recovery

Abstract

Summary In some plant–virus interactions plants show a sign of healing from virus infection, a phenomenon called symptom recovery. It is assumed that the meristem exclusion of the virus is essential to this process. The discovery of RNA silencing provided a possible mechanism to explain meristem exclusion and recovery. Here we show evidence that silencing is not the reason for meristem exclusion in Nicotiana benthamiana plants infected with Cymbidium ringspot virus (CymRSV). Transcriptome analysis followed by in situ hybridization shed light on the changes in gene expression in the shoot apical meristem (SAM) on virus infection. We observed the down‐regulation of meristem‐specific genes, including WUSCHEL (WUS). However, WUS was not down‐regulated in the SAM of plants infected with meristem‐invading viruses such as turnip vein‐clearing virus (TVCV) and cucumber mosaic virus (CMV). Moreover, there is no connection between loss of meristem function and fast shoot necrosis since TVCV necrotized the shoot while CMV did not. Our findings suggest that the observed transcriptional changes on virus infection in the shoot are key factors in tip necrosis and symptom recovery. We observed a lack of GLYCERALDEHYDE 3-PHOSPHATE DEHYDROGENASE (GAPDH) expression in tissues around the meristem, which likely stops virus replication and spread into the meristem.

Endogenous activated small interfering RNAs in virus‐infected Brassicaceae crops show a common host gene‐silencing pattern affecting photosynthesis and stress response

“…Cauliflower mosaic virus infection significantly affects diversity of endogenous small RNAs in A. thaliana, turnip, and oilseed rape Virus-infected plants usually show an uneven distribution of mosaic symptoms and yellowing of the leaves. The symptom pattern may vary among different plants and even on the same plant or the same symptomatic leaf, a phenomenon thought to be associated with heterogeneous virus-induced reprogramming of gene expression in infected tissues (Medzihradszky et al, 2019 Saunders et al, 1990). Based on the incidence of these symptoms, occurring approximately 20 dpi, turnip and OSR were classified as being highly sensitive and semi-sensitive to CaMV infection, respectively.…”

“…Virus‐infected plants usually show an uneven distribution of mosaic symptoms and yellowing of the leaves. The symptom pattern may vary among different plants and even on the same plant or the same symptomatic leaf, a phenomenon thought to be associated with heterogeneous virus‐induced reprogramming of gene expression in infected tissues (Medzihradszky et al ., 2019). Infections with CaMV typically generate mosaic symptoms in turnip and OSR.…”

Ecotype-specific blockage of tasiARF production by two different RNA viruses in Arabidopsis

“…Upon viral infection, the transcriptome of the infected host changes significantly [79][80][81][82][83]. The virus modulates the host environment in favor of its replication and spread, while the host tries to restrict the intruder and initiates an immune response.…”

Differential RNA-silencing and plasmodesmata callose deposition in leaves and stems of transgenic tobacco plants duringTobacco etch virusinfection recovery

“…Exclusion from tissues such as meristem has been attributed to RNA silencing and is considered a key step in viral recovery (31). Recent works provide evidence that silencing is not the reason for tissue exclusion of this response as DCL2/4-silenced plants infected with CymRSV were free of the virus at the meristem (32). Most of the literature describes recovery by specific components in the RNA silencing pathway rather than considering the global changes occurring in a plant during the recovery process.…”