Resistance analysis in grapefruit and mexican lime transformed with the p25 Citrus tristeza virus ge

In citrus tristeza management tolerant rootstocks have been used, but have less plasticity than C. aurantium, and crossprotection sometimes is overcome by more severe variants. An alternative may be transgenic plants with pathogenderived resistance PDR. To evaluate the conferred PDR with transgenesis plants of Citrus paradisi and C. aurantifolia, transformed via Agrobacterium tumefaciens and A. rhizogenes with the p25 gene of the Citrus tristeza virus (CTV), were multiplied in C. aurantium and C. volkameriana and inoculated by grafting and with Aphis gossypii using Mexican isolates of CTV to determine their resistance. The experimental design was completely randomized in a factorial arrangement with three replicates by treatment. The plant behavior, evaluated by real-time PCR with SYBR? Green for the p18 gene, indicated that 90 d after inoculation, the C. paradisi transgenics had lower virus concentration than those non-transformed, while C. aurantifolia allowed replication similar to non-transformed plants. Similar behavior was observed in vitro with the same materials. The analysis of results suggest a possible pathogen-derived resistance in the transgenic grapefruit lines evaluated.