Grafting as a research tool.

Grafting as a means to connect different plant tissues has been enormously useful in many studies of long-distance signalling and transport in relation to regulation of development and physiology. There is an almost infinite number of pairwise graft combinations that can be tested, typically between two different genotypes and/or between plants previously exposed to different environmental treatments. Grafting experiments are especially powerful for unambiguous demonstration of spatial separation of source and target, including genetic complementation of mutant phenotypes across a graft union, direct detection of transmitted molecules in receiving tissue or vascular sap, and activation or suppression of molecular targets due to signal transmission. Although grafting has a long history in research, only in the past decade has it been applied extensively to the Arabidopsis model. This chapter compares the main Arabidopsis grafting methods now available and describes seedling grafting in detail. Information is also provided on grafting of other common research model species, together with outlines of some successful applications.