GENETIC TRANSFORMATION OF CITRUS SINENSIS 'HAMLIN' WITH ATTACIN A DRIVEN BY A PHLOEM TISSUE-SPECIFIC PROMOTER FOR RESISTANCE TO CANDIDATUS LIBERIBACTER SPP.

Huanglongbing (HLB), associated to the bacteria Candidatus Liberibacter spp. which colonizes the phloem, is currently considered the most destructive citrus disease. Genetic transformation with genes that code for antibacterial peptides associated to phloem-specific promoters is considered an important strategy to control this disease. The objective of this work was to produce transgenic sweet orange plants expressing the attacin A gene, that codes the antibacterial peptide attacin A, associated (pCAtSuc2/attA-SP) or not with a signal peptide (pCAtSuc2/attA), driven by the Arabidopsis thaliana sucrose transporter 2 gene promoter (AtSuc2). Genetic transformation was performed with Citrus sinensis ‘Hamlin’, via Agrobacterium tumefaciens, using epicotyl segments as explants. Transgenic plants were identified by PCR analysis. The transgene integration and transcription were confirmed by Southern blot, Northern blot and RT-qPCR analyses. The results reported here confirmed the integration of the transgene, with 1 to 3 integration loci per event. The level of transgene transcription was higher in plants containing the gene construct pCAtSuc2/attA-SP. The plants will be propagated and analyzed for resistance to HLB.