Britannica Sources used in this answer

How do the cambial tissues of a stock and scion form a graft union?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

tissue culture Tissue culture often requires sterile working conditions and thus is typically performed in a laminar flow cabinet (or tissue culture hood), which circulates filtered air to reduce the risk of culture contamination.

In horticulture, the formation of a graft union relies on the regeneration of tissue at the interface of the stock and scion. The process occurs through the following steps:

Intimate Association: The cambial tissues of both the stock and the scion must be placed in close contact. This is typically achieved by ensuring a snug fit, often secured by pressure from the stock itself, grafting tape, or other binding materials.12
Callus Formation: In response to the wounding caused by cutting, the cambium of both components produces masses of undifferentiated cells known as callus tissue. Warm temperatures (typically 27–30 °C or 80–85 °F) are often used to stimulate this growth.12
Interlocking and Union: The callus tissues from the stock and scion grow over the wounded surfaces and interlock. These cells eventually fuse, creating a living, continuous connection that allows the partners to grow as a single plant.12

While tissue culture is a separate laboratory technique used for propagation, the fundamental principle of graft union formation is the successful knitting of these callus tissues.12