An overview of grafting re-establishment in woody fruit species

The formation of a successful graft includes a series of biological steps involving immediate responses to the wound, such as callus and functional vascular system formation between graft partners. However, grafts are not always successful when different genotypes (plant species) are grafted, resulting in tissue union and regeneration problems—popularly known as graft incompatibility. Numerous studies on graft union formation and graft compatibility between scion–rootstock plants have tested several scientific hypotheses related to the physiological and molecular mechanisms underlying scion–rootstock union at the early and late growth stages following the grafting of herbaceous plants. However, due to long juvenile periods, long generation times, and large plant sizes, few studies have focused on the different growth stages of grafts using woody fruit plants due to inherent difficulties in their study. In the present review, a scientific analysis of existing studies promotes a discussion of scion–rootstock grafts. If such grafts exhibit a certain level of success in their re-establishment immediately following grafting, they are termed “graft compatible.” However, if the scion–rootstock union becomes graft incompatible immediately after grafting, this is called “incompatibility,” while “late graft incompatibility” occurs when the union dies within three to five years.