Global gene expression of Candidatus Liberibacter asiaticus in different stages of development of the vector (Diaphorina citri).

Abstract

Citrus and it's sub products are one of the most important commodities of Brazil, however, since the discovery of Huanglongbing (HLB), in 2004, the sector has been suffering dramatic loses of production. The causal agents of this disease are gram-negative phloem-limited bacteria of Liberibacter genus. These bacteria spread systemically throughout the plant causing leaves and fruit abscission and promoting the plant death in a few years. Two species of bacteria occurs in Brazil: Candidatus Liberibacter asiaticus, which is present in all countries affected by HBL, with exception of African continent, and Candidatus Liberibacer americanus, endemic to Brazil. Candidatus Liberibacter africanus is another causal agent of HLB that is present in African continent only. In vitro isolation and culture of these species have been unsuccessful so far, which difficult their study. Psysilids insects are responsible for transmission of these bacteria and Diaphorina citri Kuwayama is the principal vector in America. Many studies have been developed with the aim of elucidating aspects of these pathosystem, primarily on plant-pathogen interactions and plant-insect interactions. However, studies on interaction of the pathogen and its insect vector are rare and recent. Thus, the objectives of this proposal is to identifiy differentially expressed genes of Ca. Liberibacter asiaticus in different development stages of D. citri in order to understand the genetic mechanism of interaction between the bacteria and the insect vector.