Citrus has a wide genetic diversity and the group of mandarins is that which corresponds to the highest. In Brazil, citrus production is an important segment in the socio-economic structure, characterized as an important industrial activity, qualifying the country in recent decades as the world's largest producer of oranges and the largest producer and exporter of frozen concentrated juice. Currently, huanglongbing (HLB) disease, caused by the bacterium Candidatus spp Liberibacter, is the main threat of culture, which has not yet been found tolerant species. The traditional plant breeding has shown limitations to obtain new varieties of rootstock and scion, due to the discontinuity in the programs established and factors related to the complexity of the genre. In an attempt to overcome these barriers, the transformation is notable for allowing the introduction of foreign genes, which, besides reducing the time to obtain genetically improved material may primarily confer disease resistance in varieties of agronomic interest. Thus, the objective of the research project is the study of organogenesis in vitro of epicotyl and internodal segments of mandarin, under the influence of growth regulators BAP and obtaining transgenic plants from protoplasts, epicotyl segments and internode with the gene encoding the antibacterial peptide attacin A (attA), controlled by the promoters AtSUT2 and AtPhP2, aiming to direct gene expression in phloem. Plants identified as transgenic by PCR are acclimatized and subsequently transferred to house a greenhouse specifically for growing transgenic plants. Analysis of 'Southern blot' will be held on PCR positive plants acclimatized to confirm the integration and transcription of the transgene. The first regenerated transgenic lines will be inoculated with Candidatus Liberibacter asiaticus to assess the level of resistance.
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