Overcoming biotic and abiotic stresses in the Solanaceae through grafting: current status and future perspectives

This paper reviews the status of the use of grafting in two solanaceous crops of global importance, tomato and eggplant, for the control of biotic and abiotic stresses. Flooding and soil-borne diseases cause severe crop losses of tomato during the hot and wet summer months in the lowland tropics. Asian Vegetable Research and Development Center (AVRDC) recommended since 2003 the use of eggplant rootstocks VI046103 (EG195) and VI045276 (EG203) for grafting tomato scions to provide a high degree of tolerance and resistance against flooding, bacterial wilt, root-knot nematodes and other soil-borne diseases. These two eggplant rootstocks and the tomato rootstock VI043614 (Hawaii 7996) are widely used in Southeast and East Asia for successful tomato production in both the tropical lowlands and highlands, providing significant economic returns to farmers. Given the rapid evolution of plant pathogens that might cause a breakdown of the limited rootstocks currently available, as well as the challenges of other abiotic stresses such as salinity and supra-optimal temperatures, it is necessary to expand the search for new rootstocks and evaluate new rootstock-scion combinations. Breeding and evaluation of appropriate rootstocks is still a matter of trial and error because desired rootstock traits, especially for abiotic stresses, are quite complex and regulated by multiple genes. Physiological and genetic markers to guide the selection process are still lacking but are essential to fast-track the identification of rootstocks with multiple benefits. This review supports an initiative to upgrade grafting technology through evaluation of a new and wider range of rootstocks sourced from the AVRDC genebank.