Tobacco Mosaic Virus: Factors influencing the Inhibition of Infection on Bean Leaves by Ribonuclease

Tobacco Mosaic Virus: Bean Infection Inhibition by Steapsin and Trypsin Compared with Ribonuclease

“…The findings support the following views: a) Steapsin, trypsin or RNase do not inhibit infection by enzymatic action on either the virus or the host leaf infection sites; b) Steapsin or trypsin inhibit TMV infection on bean leaves by physically coating the virus or infection sites and thus preventing virus contact with host infection site; c) RNase inhibits infection by host-site attachment to exclude virus attadiment, confirming another report (NENE and THORNBERRY 1970).…”

“…Results in figure 3 show that steapsin and trypsin were desorbed when the leaves were washed for more than one minute. RNase as reported earlier (NENE and THORNBERRY 1970) was not de-o MINUTES ' ^ '°s orbed even when the leaves were washed for ten minutes. This evidence shows Fig.…”

“…RNase inhibited strongly for the first 30 minutes then less so with time on a Iogio scale until no inhibition occurred at 1,000 mmutes, 16 hours, suggesting virus penetration into inoculated surface cells to the extent of escaping the inhlbitive enzyme protein. It was shown earlier THORNBERRY 1969, 1970) that RNase completely inhibits infection even when applied to the leaves by rubbing seven days before viral inoculation. It was of interest, therefore, to compare the behavior of steapsin and trypsin with RNase under similar conditions.…”

“…Thus, the findings might point up whether the proteins act enzymatically to inhibit infection. Ribonuclease (RNase) reported to inhibit infection by adsorption to leaf surface THORNBERRY 1969, 1970), served as an enzyme protein control. The findings indicate that steapsin and trypsin in inhibiting infection act by preventing virus contact with the host.…”