Abstract
Plant grafting is conducted for vegetative propagation in plants, whereby a piece of living tissue is attached to another tissue through establishment of cell–cell adhesion. Plant grafting has a long history in agriculture and has been applied to improve crop traits for thousands of years1. Plant grafting has mostly relied on the natural ability of a plant for wound healing. However, the compatibility of cell–cell adhesion typically limits graft combinations to closely related species2–4, and the mechanism by which cell–cell adhesion of injured tissues is established is largely unknown. Here, we show that a subclade of β-1,4-glucanases secreted into the extracellular region facilitates cell–cell adhesion near the graft interface. Nicotiana shows a propensity for cell–cell adhesion with a diverse range of angiosperms, including vegetables, fruit trees, and monocots, in which cell wall reconstruction was promoted in a similar manner to conventional intrafamily grafting5–7. Using transcriptomic approaches, we identified a specific clade of β-1,4-glucanases that is upregulated during grafting in successful graft combinations but not in incompatible grafts and precedes graft adhesion in inter- and intrafamily grafts. Grafting was facilitated with an overexpressor of the β-1,4-glucanase and, using Nicotiana stem as an interscion, we produced tomato fruits on rootstocks from other plant families. Our results demonstrate that the mechanism of cell–cell adhesion is partly conserved in plants and is a potential target to enhance plant grafting techniques.
