Shoot meristem tissue of tobacco inoculated with Cucumber mosaic virus is infected with the virus and subsequently recovers from infection by RNA silencing

Abstract

Distribution of Cucumber mosaic virus (CMV) in shoot meristem tissue of CMV-inoculated tobacco was successively analyzed with immunohistochemical microscopy and in situ hybridization. CMV signals were detected in the tissue at 7 days postinoculation (dpi), but then they decreased and disappeared after 14 dpi. Detailed observation confirmed CMV invasion of shoot apical meristem at 6-8 dpi. Short interfering RNA corresponding to CMV RNAs was first detected at 7 dpi and was detected up to 24 dpi. These results suggest that the shoot meristem tissue is infected with CMV but subsequently recovers from the infection by RNA silencing.

The 2b protein of cucumber mosaic virus is essential for viral infection of the shoot apical meristem and for efficient invasion of leaf primordia in infected tobacco plants

“…1a). These results correlated with the results of a previous study (Mochizuki & Ohki, 2004). In D2b-infected shoot meristem, large amounts of D2b vRNA were detected at 7 and 10 days p.i., but accumulation decreased from 14 to 18 days p.i.…”

“…Procedures for the preparation of shoot meristem and LP sections from inoculated tobacco plants, immunohistochemistry using anti-CMV IgG and in situ hybridization using a digoxigenin (DIG; Roche Diagnostics)-labelled RNA probe complementary to the conserved 39 untranslated region (39-UTR) sequence of the four CMV positive-sense RNAs (Saitoh et al, 1999) were conducted using methods described previously (Mochizuki & Ohki, 2004). The stained sections were examined with a BX-50 light microscope (Olympus).…”

“…Hybridization was performed using DIG-labelled, full-length CMV RNAs complementary to the CMV negative-sense RNAs transcribed from Pepo CMV clones (Saitoh et al, 1999). The procedures for hybridization and detection of signals were performed as described previously (Mochizuki & Ohki, 2004).…”

“…Because the expression of mosaic symptoms has been implicated in virus distribution in leaf primordia (LP) of infected plants (Hosokawa et al, 1990), we hypothesized that 2b mediates virus distribution in developing tissues, including the shoot apical meristem (SAM) and LP. We showed previously that Pepo could infect SAM cells, but the shoot meristem tissues recovered from the Pepo infection (Mochizuki & Ohki, 2004, 2005. Recently, a requirement for the 16K suppressor protein of tobacco rattle virus (TRV) for SAM invasion by TRV was reported (Martín-Hernández & Baulcombe, 2008).…”

Leaf Primordia-Free Shoot Apical Meristem Culture: A New Method for Production of Viroid-Free Plants

“…PTGS on cucumber mosaic virus (CMV) RNA was observed in virus-infected tobacco SAMs (Mochizuki and Ohki, 2004). Inoculated CMV successfully invaded SAMs and accumulated, the virus titer then decreased, and finally could not be detected by in situ hybridization.…”