Breeding for crown gall resistance:: Traditional and molecular approaches

Grapevine crown gall disease, induced mainly by Agrobacterium vitis, causes serious economic losses in several countries. Selection, breeding and genetic engineering of tolerant genotypes are alternative strategies for the effective and sustainable control of the disease. To this end, extensive studies were carried out in Hungary, South-Africa, in the United States and Germany to identify crown gall-tolerant rootstocks and genotypes for breeding resources. The results of these studies revealed that Vitis riparia cv. portalis, V riparia cv. Gloire de Montpellier, and several accessions of V amurensis, as well as their hybrids, responded to Agrobacterium infection with minimal or no tumor formation. V. amurensis inherited crown gall tolerance to its progenies as a single Mendelian trait. Further studies were performed to gain insight into the mechanisms that underlie tolerance. Genetic manipulation of grapevines for crown gall resistance may provide further possibilities to protect traditional varieties. These methods include the inactivation of plant genes that are essential for transformation by Agrobacterium T-DNA as well as introduction of foreign genes that prevent tumor formation. The application of these strategies may provide an efficient tool for engineering crown gall-tolerant grapes in the near future.