Gene expression analysis in sensitive and tolerant Citrus rootstocks under chlorotic conditions

Iron chlorosis is one of the major abiotic stresses affecting fruit trees and other crops in calcareous soils. The most evident symptoms are connected to a reduction in growth and yield and in the interveinal chlorosis of leaves. A custom CombiMatrix 90K microarray was used to identify candidate genes involved in the citrus response to iron deficiency stress, comparing Tarocco Scirè orange [Citrus sinensis (L.) Osbeck] grafted on two different rootstocks, Swingle citrumelo (C. paradisi × Poncirus trifoliata), high sensitive, and Carrizo citrange (C. sinensis × P. trifoliata), tolerant. RNA was extracted from roots of plants grown in two different soils, one volcanic (0% of active lime) used as control, and the other calcareous (10% of active lime). Root tips of two citrus rootstocks, Carrizo Citrange and Swingle Citrumelo, respectively tolerant and sensitive to iron deficiency, each grown in two different soil (volcanic, considered as a control with 0% of active lime, and chlorotic, with 10% of active lime) were analyzed. Three biological replicates were taken for each sample, resulting in a total of twelve observations.