Physiological, Environmental, and Molecular Factors Govern the Success of Grafting in Plants

Abstract Grafting is a common practice in horticulture used for the selection and maintenance of uniformity in specific desired plant traits. The extraordinary regenerative ability of grafted plants, where a scion is cut and joined with a rootstock to fuse and grow as a single, re-established plant, depends on numerous factors. In this review, we studied over 100 publications in an effort to summarize the reported pre-grafting factors (e.g., botanical relatedness, scion and rootstock quality, and grafting-techniques), as well as abiotic (e.g., environmental and cultural), and biotic (e.g., morphological, physiological, and genetic) factors that affect grafting success and plant re-establishment (i.e., graft compatibility and in-compatibility). For example, environmental factors affecting grafting success include season, dormancy periods of scion-source trees, temperature, light, and orientation towards sunlight, while cultural factors include various grafting and bud-forcing methods. The morphological factors described in the literature involve visual observations of phenotypic growth and development, morphological attributes, and the age of the plant. We focused on different studies of physiological factors, including anatomical and biochemical influences on grafting, such as the alignment of cambium tissues, leaf gas exchange, and the movement of water and ions/mineral elements. The reviewed genetic factors included basic molecular responses at the graft interface, movement of DNA, RNA, and proteins, as well as gene expression in response to grafting. Finally, the metabolic factors described in grafted plants include primary and secondary metabolites, phytohormones, and phenolic compounds. Through this comprehensive overview of these factors, we aim to provide readers with a basic understanding of their underlying role in grafting, potentially guiding decisions that could improve grafting success rates. Improving grafting success is one of the crucial first steps for the economic success of farmers or growers and to meet the global demand for food. The research on crop-specific mechanisms of grafting success including graft compatibility and incompatibility must continue to provide critical data and answers to unresolved questions on the subject.