Mechanical Sap Transmission of Geminiviruses

Mechanical sap transmission is the simplest, quickest, and most cost-effective method to transmit geminiviruses (and indeed any plant virus) from one plant to another. However, a significant number of geminiviruses, which are phloem-restricted in their hosts, are not transmitted in this form. For those geminiviruses which do invade the mesophyll, mechanical transmission is possible. The procedure consists of grinding virus-infected plant material (usually leaves) in a buffer solution and rubbing the plant sap onto the surface of the leaves of a healthy plant, which have been sprinkled with an abrasive powder. Injury to the epidermal cells (maximized by the presence of the abrasive powder) allows viral particles to enter the cell and initiate infection.