Iron Metabolism in Tomato and Watermelon Plants: Influence of Grafting

Abstract

Citrullus lanatus [Thomb.] Mansf var. F-90 were grafted onto the rootstock of Cucubirta maxima var. Dulce maravilla, and Lycopersicon esculentum var. Tmknvf₂ plants were grafted onto the rootstock of Lycopersicon esculentum var. TmKnvf₂. Ungrafted Citrullus lanatus [Thomb.] Mansf var. F-90 and Lycopersicon esculentum var. Tmknvf₂ were used as controls. Plants were grown under controlled conditions and fertilized constantly with macro- and micronutrients. The aim of the present study was to measure whether the variability in the nutritional status of iron (Fe) and the behavior of its main bioindicators in grafted plants is due to the vigor of the scion, or, on the contrary, to the influence of the rootstock. With this aim, we analyzed in the roots and leaves the concentrations of total and free Fe, as well as the enzymatic activities of Fe(III)-chelate reductase, peroxidase, catalase, aconitase, and ferro-superoxide dismutase. Results of this study indicate a contrary behavior, according to the two genotypes analyzed. In the grafted watermelon plants, the rootstock used (Cucubirta maxima var. Dulce Maravilla) augmented Fe uptake as well as the subsequent translocation of this micronutrient towards the shoot in relation to results for control (ungrafted watermelon plants). On the contrary, in the grafted tomato plants, although the rootstock var. TmKnvf₂ showed greater capacity for Fe uptake and accumulation than in control, these facts are not reflected in the shoots of var. RX-335, clearly signifying that the vigor of the scion predominated over the foliar control in terms of the nutritional state of Fe in the tomato plants, or else incompatibility between the different parts of the grafted tomato plants. Finally, all the bioindicators analyzed clearly reflected both the uptake and the nutritional status of Fe in the genotypes studied.

Keywords:

• Bioindicators
• Aco
• POD
• CAT
• FeSOD
• FeCH-R
• Genotype
• Graft
• Rootstock
• Scion