Scientists find an enzyme that facilitates grafting between different family species

Their findings, published recently in the journalScience,have also shown that using tobacco as an intermediary, the upper part (scion) of a tomato plant grafted onto the lower part (rootstock) of aChrysanthemum morifolium(widely known as Florist's daisy) successfully bore fruit.

Grafting has been conducted for thousands of years for the propagation of fruits and vegetables, in which a productive scion is attached onto a rootstock that is resistant to diseases and environmental stresses. However, exactly how grafts are established has been unclear, and grafting is considered difficult between different family species.

A team of scientists from Nagoya University, Teikyo University, RIKEN, Chubu University, and GRA&GREEN Inc. (a start-up venture company from Nagoya University) recently conducted a study on grafting between different family species.

The team focused onNicotianain the Solanaceae family, because a previous study had shown that its scion can be grafted onto the rootstock ofArabidopsis thalianain the mustard family. The team conducted grafting experiments using plants of sevenNicotianaspecies and their partners from 84 species in 42 families. The results showed thatNicotiana, used as either scion or rootstock, succeeded in maintaining grafts for more than a month with 73 species in 38 families.

Next, the scientists examined the cellular mechanisms that enableNicotianato form grafts with plants from a wide range of families. They analyzed transcriptomes at graft junctions betweenNicotiana和Arabidopsis和hypothesized that the expression of β-1,4 glucanases secreted into the extracellular region is involved in cell wall digestion. In further experiments, when β-1,4 glucanases were overexpressed inArabidopsis,移植的附着力属性增强. Thus, they concluded that the expression of β-1,4 glucanases is a key in facilitating tissue adhesion of the grafts.

In addition, they conducted experiments to see whetherNicotianacan act as an intermediary in the grafting of different family species, by using a tomato scion and the rootstock of Florist's daisy,a garden plant resistant to environmental stress. About three months later, the tomato plant successfully produced a small fruit.

"UsingNicotianaas an intermediate, we also achieved other grafts in which the scion, interscion, and rootstock all belonged to different plant families," says Nagoya University bioscientist Michitaka Notaguchi, the corresponding author of this study.

"Our latest results regarding the key molecules involved, not just interfamily grafting itself, could help improve plant grafting techniques so that the variety of root systems available to aid crop production can be increased with minimal destruction of ecosystems."