Jamily Maria de Almeida Silva¹, Larissa Nascimento da Silva¹, Mara Danielle Silva do Carmo², Tercilio Calsa Junior¹

The prickly pear (Opuntia spp., Cactaceae) holds economic importance in the Brazilian Semi-arid region due to its use as livestock feed, drought tolerance and its nutritional value in non-fibrous carbohydrates. The cultivation of this crop has been threatened by the armored scale (Diaspis echinocacti Bouché), an insect pest that extracts sap from the cladodes, causing tissue rot and, in severe cases, plant death. The lack of resistant varieties impairs the control of this insect. In this context, the identification of molecules associated with plant responses to armored scale attack may contribute to the identification and/or development of resistant varieties. In silico studies performed by the Laboratory of Plant Genomics and Proteomics (LGPP) indicated the involvement of TIFY9 protein in the prickly pear stress responses in through jasmonic acid (JA) mediated signaling, where the proteins JAR1, COI1, JAZ group (also studied by the research group) and MYC2 participate. The present study was developed to investigate, through in silico analysis, the conservation of JAR1, COI1 and MYC2 proteins in species of the genus Opuntia, in order to understand defense signaling pathways mediated by JA. The analyses were conducted from UniProt accessions of Arabidopsis thaliana JAR1 (Q9SKE2), COI1 (O04197) and MYC2 (Q39204), of . Using these sequences, BLASTp searches were performed at NCBI, restricted to the Opuntia genus (e-value <= 10^-5). Through the alignments, proteins with similarity equal to or greater than 40% were selected and the conserved domains were analyzed via CD-Search. The protein-protein interaction network was constructed using STRING. Orthologous proteins were identified in Opuntia streptacantha. For JAR1 results, five proteins showed significant similarity, all having the GH3 domain (known as an auxin-responsive promoter) along most of the protein sequence. For COI1, only one protein with 60% similarity was identified containing several characteristic domains of the reference protein, except the FBXL3_LRR domain, which confers specificity of binding to the substrate. The alignment of the MYC2 protein revealed high heterogeneity in amino acid residues and conserved domains positioning among the 16 proteins found. However, all sequences featured domains from the bHLH superfamily, characterized by the DNA-binding site. The analysis of the interaction network reinforced the functional interconnection among the studied proteins in the regulation of the defense response. In addition, COI1 and MYC2 interacted with all other proteins of the pathway and with each other, evidencing their central role in JA-mediated signaling. The in silico characterization of the proteins involved in JA-mediated signaling indicates their functional conservation in Opuntia spp., suggesting that mechanisms similar to those described in A. thaliana occur in prickly pear during the armored insect infestation. These findings can support breeding programs of this crop, since the identification and characterization of these proteins can favor the selection of varieties that are more tolerant and/or resistant to armored insect. Thus, future studies can investigate the regulation of the expression of these proteins for a better understanding of their role in mitigating agricultural losses caused by the pest.

Agradecimentos: Laboratory of Plant Genomics and Proteomics (LGPP), Instituto Agronômico de Pernambuco (IPA), Federal University of Pernambuco (UFPE) and Fundação de Amparo à Ciência e Tecnologia de Pernambuco (FACEPE).