Comparative Genomics-based Identification and Functional Characterization of Key Genes Resisting Huanglongbing in Citrus

doi:10.13560/j.cnki.biotech.bull.1985.2025-0389

Abstract

Abstract:

Objective The identification of disease-tolerance genes is essential for breeding Huanglongbing (HLB)-resistant citrus germplasm. In order to elucidating the molecular mechanisms underlying citrus-Candidatus Liberibacter asiaticus (CLas) interactions, key HLB-resistant genes in Citrus spp. and closely-related plants were screened. Method Key genes in dieease-resistant materials were systematically identified using comparative genomics. Core differentially expressed genes (DEGs) were characterized through resistance-specific gene cluster analysis, conserved orthologous group identification, Gene Ontology (GO) enrichment, transcriptome profiling, and protein-protein interaction network analysis. Result Multiple HSP70 genes demonstrated significantly modulated expression patterns upon CLas infection among defense-related DEGs induced by the pathogen. The overexpression of HSP70 substantially enhanced citrus resistance against bacterial pathogens. Conclusion The defense-associated gene HSP70 positively regulates disease resistance to pathogens in citrus.

Key words: citrus, Huanglongbing, comparative genomics, disease tolerance, heat shock protein 70

HU Yan-an, DAI Xin-lyu, ZHONG Jiao-yan, LI Rui-min, HUANG Gui-yan. Comparative Genomics-based Identification and Functional Characterization of Key Genes Resisting Huanglongbing in Citrus[J]. Biotechnology Bulletin, 2025, 41(11): 282-292.

Figures/Tables 9

Fig. 1 Clustering analysis of gene families across 11 speciesProteins indicate the non-redundant protein sequences of each species. Clusters indicate the orthogroups (orthologous gene clusters) across species. Singletons indicate the single-copy gene clusters specific to each species

Fig. 2 Identification of common orthogroups in different species

Fig. 3 GO enrichment analysis of proteins in common orthogroups from HLB-resistant speciesA: Citrus australasica and C. hongheensis; B: C. ichangensis and C. hongheensis; C: C. mangshanensis and C. ichangensis

Fig. 4 Common orthogroups analysis from five HLB-resistant speciesA: Common orthogroups analysis; B: GO enrichment analysis; C: transmembrane domain analysis

Fig. 5 Analysis of gene family expansion and contraction

Fig. 6 GO enrichment analysis of expanded gene family in C. australasica

Fig. 7 Expression patterns of genes related to the expanded gene family in C. australasicaA: “Defense response” related genes; B: “phenylpropanoid metabolic process” related genes

Fig. 8 Constructing protein-protein interaction network of up-regulated HSP70 proteins

Fig. 9 Subcellular localization and disease resistance analysis of HSP70A: Subcellular localization of HSP70, scale bar=50 μm. B: Analysis of the disease resistance of overexpressed HSP70 to citrus canker. Used t-test for statistical significance analysis, *** denotes P<0.001

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