Abstract:The grafting of excised hypocotyl segment of plant in sterile culture is described in which two explanted internodes are grafted together in sterile culture and then inserted between two agar surfaces and incubated under light. It imitates the normal physiological process, and is a controllable experimental system. Development of the graft union is similar to that observed in whole-plant graft unions, including a sequence of several distinct steps: initial cohesion of stock and scion; proliferation of callus at graft interface; symplastic interconnection of individual cells of graft partners by secondarily formed plasmodesmata; and vascular bridge formation. The process of development is regulated by plant hormones such as auxin and cytokinin. Clearly this system can be used as a powerful tool in demonstrating the mechanisms of graft formation and graft compatibility.