As the processing mechanism of all known potyviruses involves the activity of cysteine proteinases, we asked whether constitutive expression of a rice cysteine proteinase inhibitor gene could induce resistance against two important potyviruses, tobacco etch virus (TEV) and potato virus Y (PVY), in transgenic tobacco plants. Tobacco lines expressing the foreign gene at varying levels were examined for resistance against TEV and PVY infection. There was a clear, direct correlation between the level of oryzacystatin message, inhibition of papain (a cysteine proteinase), and resistance to TEV and PVY in all lines tested. The inhibitor was ineffective against tobacco mosaic virus (TMV) infection because processing of this virus does not involve cysteine proteinases. These results show that plant cystatins can be used against different potyviruses and potentially also against other viruses, whose replication involves cysteine proteinase activity.

A rapid and simple procedure is described for efficiently extracting intact RNA from mango (Mangifera indica L. cv. Manila) mesocarp, a tissue rich in polysaccharides. The RNA can be used for in vitro translation, northern blots, and cDNA synthesis. This method is applicable to other fleshy fruits rich in polysaccharides.

No abstract

Plant molecular farming: challenges and opportunities.