Phenolic metabolism in grafted versus nongrafted cherry tomatoes under the influence of water stress.

Use of grafts using rootstocks capable of palliating the effects of water stress can be a possible solution to reduce yield losses. For response to stress, plants can induce the metabolism of phenylpropanoids. The aim of the present work is to determine the response of reciprocal grafts made between one tolerant cherry tomato cultivar, Zarina, and a more sensitive cultivar, Josefina. The analysis of the phenylpropanoids pathway was carried out both enzymatically and metabolically. DAHP synthase, shikimate dehydrogenase, phenylalanine ammonium-lyase, cinnamate 4-hydroxylase, and 4-coumarate CoA ligase activities were determined, and characteristic metabolites from the pathway were measured by means of HPLC-MS. Growth in the grafts JosxZar and ZarxJos was not appreciably affected by stress. JosxZar had increased concentrations of phenolic compounds after water stress. This could be correlated with the greater activity of synthesis enzymes as well as a decrease in phenol-degrading enzymes. Phenolic metabolism is more influenced by the aerial part, and therefore it is concluded that the capacity of inducing tolerance in rootstocks depends on the genotype of the shoot.