Identification and characterization of protein biomarkers of sugarcane stress response under the action of Xanthomonas albilineans

Fabiana Aparecida Cavalcante Silva1,2, Cássio David Alves da Paz3, Greecy Mirian Rodrigues Albuquerque1, Carolina Elstein1, Rafael José Vilela de Oliveira1, Carlos Eduardo Alves2, James Correia de Melo1, Tercilio Calsa Junior4, Bianca Galúcio Pereira Araújo1

1. CETENE, Centro de Tecnologias Estratégicas do Nordeste; Av. Prof. Luiz Freire, 01 - Cidade Universitária, Recife - PE
2. UFRPE, Universidade Federal Rural de Pernambuco; Rua Dom Manuel de Medeiros, s/n - Dois Irmãos, Recife - PE
3. UPE, Universidade de Pernambuco; R. Arnóbio Marques, 310 - Santo Amaro, Recife - PE
4. UFPE, Universidade Federal de Pernambuco; Av. Prof. Moraes Rego, 1235 - Cidade Universitária, Recife - PE

Sugarcane (Saccharum spp.), a crop of major economic importance by producing commodities such as sugar and first- and second-generation biofuels, is affected by biotic and abiotic stressors. Among biotic factors, the leaf scald disease caused by the Gram-negative bacterium Xanthomonas albilineans (Xal) is particularly detrimental to yield. This pathogen reduces sugarcane productivity through asymptomatic initial colonization, facilitating its spread via contaminated planting material (“seed” cane, actually stem nodal segments) and leading to significant yield losses after symptoms emergence. This study investigated alterations in the sugarcane protein profile in response to X. albilineans infection, focusing on differential leaf proteome of the RB867515 commercial hybrid. The experiment was performed under controlled greenhouse conditions using the CTNXal29 Xal isolate. Total soluble proteins were extracted via phenolic method and analyzed through nUPLC-MS/MS. Spectral data processing and protein identification were performed using MaxQuant software, while statistical analysis and selection of differentially accumulated proteins (DAPs) (control vs. inoculated) were carried out in Perseus. Functional categorization (gene ontology, interactome) utilized ShinyGO, STRING, KEGG, UniProt, Panther, agriGO and RStudio. Out from a total of 413 identified proteins, 396 were differentially accumulated. From these, 214 were more abundant in control and 190 in the treated samples. In inoculated plants, a higher accumulation of proteins related to genetic information processing was observed, particularly proteins involved in miRNA production [A0A1D6EFA3; fold change (FC) 14.37], DNA methylation (B9EU39; FC -4.88) and genome repair (A0A3L6G452; FC 7.72). These findings suggest that X. albilineans infection modulate the sugarcane proteome, triggering an integrated stress response which seems to prioritize DNA repair and transcriptional regulation. The identified proteins serve as potential biomarkers to develop more tolerant varieties against Xal using precision genetic strategies, such as marker-assisted selection or gene editing. Additionally, this work highlights the value of proteomic and bioinformatic tools on studying sugarcane-pathogen interactions, supporting improved leaf scald control.

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