Comparative Analysis of genes involved in iron homeostasis in grapevine rootstocks characterized by contrasting tolerance to iron chlorosis

Iron chlorosis is an important nutritional disease that affects orchards and vineyards reducing quality and yield production. In soil, high calcareous conditions affect pH, raising it to sub-alkaline and alkaline levels and maintaining iron in an insoluble form as Fe3+. Chlorotic plants show abnormal photosynthesis and yellowing shoots. Nowadays the most used protection against iron chlorosis is grafting the varieties of economic interest on tolerant rootstocks. Genetic improvement of fruit trees plays an important role on the selection of iron chlorosis resistant rootstocks using breeding techniques. In grapevine, this selection is based on breeding varieties belonging to the V. vinifera species with non vinifera ones (i.e. wild American species). In grapevine, iron uptake and homeostasis are controlled by a mechanism known as “Strategy I”, characteristic of non-graminaceous plants and based on a system of iron reduction, soil acidification and transporters-mediated uptake. In this study, main Strategy I-genes involved in iron uptake were identified and analysed in two grapevine rootstocks characterized by different levels of tolerance and susceptibility to iron chlorosis. Expression analyses on selected genes under different iron-availability conditions revealed important differences which could explain the different degree of tolerance observed in the two genotypes under study.