Grapevine roots: the dark side
Résumé
Since the second half of the XIXth century, grapevine has been grown grafted worldwide to cope with Phylloxera. Consequently, the cultivated grapevine is a chimeric plant made from two genotypes which interact together. The result of this interaction must ensure a balanced functioning dedicated to fruit production in terms of quantity and quality. The rootstock acts as an interface between the edaphic environment and the scion, and is an important component of adaptation to environment. The rootstock is responsible for the uptake of water and minerals from the soil, feeding the aerial parts in exchange for a supply of carbon that is stored as reserves, or used to produce nutrients and growth regulators. Many signaling and regulating molecules, such as hormones and nucleic acids, are also exchanged between the two partners. Despite its importance, little is known about the root system and the grafting zone (rootstock-scion interface) in grapevine. Until recently the study of rootstocks received little attention from growers and the scientific community. New challenges, such as climate change, environmental issues, and yield limitations, have brought new light on the “dark side” of the grapevine. This paper reviews the main physiological processes involved in the functioning of roots and the graft interface. Key, challenging scientific issues as well as applied perspectives for the industry will be discussed.