Understanding scion-rootstock interactions at the graft interface of grapevine
Abstract
In viticulture, grafting is used to facilitate grapevine cultivation in soils infected with phylloxera, a soil-dwelling insect pest introduced to Europe from America at the end of the 19th century. Successful grafting of plants is a complex biochemical and structural process that begins with an initial wound response, followed by callus formation and the establishment of a functional vascular system between the two grafting partners. Despite the importance of the scion-rootstock interface in viticulture, we know little of the processes involved in forming a successful graft union. Developments at the scion-rootstock interface of grapevine have been studied using a variety of techniques. Morphological developments have been studied using microscopy techniques and X-ray computed tomography, and xylem connectivity has been assessed by using a high- and low-pressure flow meter. Microarrays have been used to identify genes that are differentially expressed between the wood and graft interface tissues of homo-grafts (the same genotype grafted together) and at the graft interface between different scion-rootstock combinations (hetero-grafts). Primary and secondary metabolite profiling has also been done. An overview of the interdisciplinary approaches currently being used to piece together the puzzle of graft union formation in an important woody, perennial crop will be presented.