Distribution Characteristics of TSWV Virions in Vascular Tissues of the Systemic Host Tobacco K326

In this study, the distribution of tomato spotted wilt virus(TSWV) in vascular tissues of systemic host tobacco K326 was observed by transmission electron microscopy (TEM) to analyze the long-distance transportation of TSWV. The results showed that vesicle-enveloped viral particles and nuclear capsid aggregates (NCA) were found in vessel elements. Vesicle-enveloped viral particles were found in vascular parenchyma cells, and there were more vesicles in cytoplasm than the CK. Vesicle-enveloped viral particles were found in companion cells, and a large number of vesicles with a diameter of about 120 nm were found in cytoplasm. At the same time, pathological changes in mitochondria were also found, including the expansion and disappearance of the mitochondrial stroma lamella. There was no viral particles in the sieve element, but vesicles with a diameter of about 80-200 nm were found in the sieve element. Our finding suggested that the TSWV virions are likely transported by xylem, and the TSWV vesicle-related complexes (VRC) may be transported by phloem.