Characterization of Proteins Involved in Chloroplast Targeting Disturbed by Rice Stripe Virus by Novel Protoplast–Chloroplast Proteomics

Abstract

Rice stripe virus (RSV) is one of the most devastating viral pathogens in rice and can also cause the general chlorosis symptom in Nicotiana benthamiana plants. The chloroplast changes associated with chlorosis symptom suggest that RSV interrupts normal chloroplast functions. Although the change of proteins of the whole cell or inside the chloroplast in response to RSV infection have been revealed by proteomics, the mechanisms resulted in chloroplast-related symptoms and the crucial factors remain to be elucidated. RSV infection caused the malformation of chloroplast structure and a global reduction of chloroplast membrane protein complexes in N. benthamiana plants. Here, both the protoplast proteome and the chloroplast proteome were acquired simultaneously upon RSV infection, and the proteins in each fraction were analyzed. In the protoplasts, 1128 proteins were identified, among which 494 proteins presented significant changes during RSV; meanwhile, 659 proteins were identified from the chloroplasts, and 279 of these chloroplast proteins presented significant change. According to the label-free LC–MS/MS data, 66 nucleus-encoded chloroplast-related proteins (ChRPs), which only reduced in chloroplast but not in the whole protoplast, were identified, indicating that these nuclear-encoded ChRPswere not transported to chloroplasts during RSV infection. Gene ontology (GO) enrichment analysis confirmed that RSV infection changed the biological process of protein targeting to chloroplast, where 3 crucial ChRPs (K4CSN4, K4CR23, and K4BXN9) were involved in the regulation of protein targeting into chloroplast. In addition to these 3 proteins, 41 among the 63 candidate proteins were characterized to have chloroplast transit peptides. These results indicated that RSV infection changed the biological process of protein targeting into chloroplast and the location of ChRPs through crucial protein factors, which illuminated a new layer of RSV–host interaction that might contribute to the symptom development.

Comparative proteomic analysis of Nicotiana benthamiana plants under Chinese wheat mosaic virus infection

“…In the current study, expression levels of acidic endochitinase Q from a significantly enriched MAPK signaling pathway was up-regulated over 48-fold following CWMV infection (Table 1 ), which indicated that the glyoxylate and dicarboxylate metabolism pathway played an important role in the response of N. benthamiana plants to CWMV infection. Plant RNA viral infections typically elicit leaf chlorosis, necrosis, plant stunting, and other symptoms, and leaf chlorosis frequently leads to decreased photosynthetic activity of the chloroplast [ 37 , 38 ]. The chlorophyll a/b proteins (CAB) from the photosynthesis antenna protein pathway are membrane proteins that are vital for capturing light energy by merging with pigment molecules for photosynthesis [ 39 ].…”

Comparative Proteomic Analysis of Nicotiana Benthamiana Seedings Under Chinese Wheat Mosaic Virus Infection

“…In our study, the expression level of acidic endochitinase Q from significantly enriched MAPK signaling pathway was up-regulated over 48-fold by CWMV infection (Table 1), which indicated that MAPK signaling pathway played an important role in the response of N. benthamiana to CWMV infection. Plant RNA viral infection usually leads to leaf chlorosis, necrosis, plant stunting or other symptoms, and leaf chlorosis is often consistent with decreased photosynthetic activity of the chloroplast [36,37]. The chlorophyll a/b proteins (CAB) from Photosynthesis -antenna proteins pathway are vital membrane proteins for the capture of light energy by combining with pigment molecules in photosynthesis [38].…”

The Bunyavirales: The Plant-Infecting Counterparts

“…Genes related to chlorophyll synthesis are predominantly suppressed by RGSV infection [ 84 ]. RSV infection also disturbs chloroplast targeting of host proteins [ 88 , 89 , 90 ], and the downregulation of chloroplast genes by RSV infection has been shown to be associated with chlorosis [ 86 ].…”