Genetic transformation of Citrus sinensis (L.) Osbeck for resistance to Candidatus Liberibacter ssp

Abstract

The citrus industry in Brazil has been affected by several diseases. Huanglongbing (HLB) is a citrus disease caused by endogenous sieve tube-restricted bacteria named Canditatus Liberibacter ssp that has caused serious problems to the crop. The genetic transformation represents an important tool that can be utilized in order to obtain disease resistance plants. A strategy to obtain transgenic plants resistance to phytopathogenic bacteria is based on the introduction of antimicrobial peptides genes. The objective of this work is to produce transgenic sweet orange plants 'Hamlin', 'Natal', 'Pera' and 'Valencia' expressing the antimicrobial peptide gene attacin A (attA) controlled by AtSUT2 and CsPP2 promoter in order to direct gene expression to phloem vessels. The genetic transformation will be performed with Agrobacterium tumefaciens, containing pCAMBIA 2201 with expression cassette. The experiments of genetic transformation will be performed with epicotyl segments as explants, collected from plantlets cultivated in vitro. The genetic transformation will be confirmed by PCR analysis and the PCR positive plantlets will be acclimatized and cultivated in specific greenhouse for transgenic plants. The confirmation of transgene integration and transcription will be performed by Southern and Northern analysis. The transgenic lines obtained will be evaluated for resistance to Candidatus Liberibacter asiaticus.