Caracterização de plantas transgênicas de Citrus sinensis com aumento na volatização de metil-salicilato e Resistência Sistêmica Adquirida no patossistema HLB

Abstract

Currently, Huanglongbing (HLB) has been considered the most devastating disease of citrus worldwide. In Brazil, the disease is caused by the bacterium Candidatus Liberibacter asiaticus (CLas), which colonizes the phloem vessels of citrus plants, causing severe symptoms in leaves and fruits. Naturally, the bacterium is transmitted by Diaphorina citri, which acquires CLas when feeding on infected plants and transmits it to healthy ones. The use of chemical pesticides has been widely used to control the vector, but with negative consequences for the environment, in addition to enhancing the development of resistant insects. Genetically modified plants have been studied as an alternative to mitigate the transmission of CLas. The SAMT gene encodes an enzyme that catalyzes the reaction of salicylic acid (SA) to a volatile signal known as methylsalicylate (MeSA), which is involved in the signaling pathway of the plant defense system, activating Systemic Acquired Resistance (SAR). Recently, SAMT overexpression has been shown to be involved in HLB resistance. However, the production of volatile MeSA can affect the behavior of the insect, acting as an attractant for plants. With this, for the development of the work using transgenic plants that overexpress the CsSAMT gene and present high levels of MeSA. Thus, we hypothesize that plants that overexpress the CsSAMT gene, by volatilizing Methyl salicylate, are more attractive to D. citri, but more resistant to HLB due to the activation of SA-mediated defense mechanisms. However, among the results obtained in our study, we concluded that the transformed plants that volatize MeSA were not more attractive to the insect vector, on the contrary, they were less preferred by them. And as for the resistance of the plants, after inoculation of the bacteria, no significant difference was observed in the colonization of CLas between the plants.