Identification of viral particles in the apoplast of Nicotiana benthamiana leaves infected by potato virus X

• Published in: Molecular plant pathology 2021-04, Vol.22 (4), p.456-464
• Main Authors: Hu, Shuzhen, Yin, Yueyan, Chen, Buyang, Lin, Qi, Tian, Yanzhen, Song, Xijiao, Peng, Jiejun, Zheng, Hongying, Rao, Shaofei, Wu, Guanwei, Mo, Xiaohan, Yan, Fei, Chen, Jianping, Lu, Yuwen
• Format: Article
• Language: English
• Subjects: Analysis; apoplast; coat protein; exosomes; Nucleic acids; potato virus X; Potatoes; viral particles
• ISSN: 1464-6722; 1364-3703
• DOI: 10.1111/mpp.13039

The apoplast is the extracellular space for signalling, nutrient transport, and plant–microbe interactions, but little is known about how plant viruses use the foliar apoplast. Proteomic analysis of the apoplasts isolated from potato virus X (PVX)‐infected Nicotiana benthamiana plants showed that the coat protein (CP) is the dominant viral component. The presence of the CP in the apoplast was confirmed by western blot, viral nucleic acid was detected by reverse transcription‐PCR and northern blot, and viral particles were observed by transmission electron microscopy (TEM). The apoplast from infected leaves was infectious if rubbed onto healthy leaves but not when infiltrated into them. The exosomes were separated from the apoplast fluid by high‐speed centrifugation and TEM showed that PVX particles were not associated with the exosomes. These results suggest that PVX virions are released to the N. benthamiana apoplast in a one‐way manner and do not share the bidirectional transport of exosomes. The presence of potato virus X (PVX) viral particles was identified in the leaf apoplast isolated from PVX‐infected Nicotiana benthamiana. This apoplast was infectious onto healthy leaves by rubbing them but not by infiltration.