ORIGINAL RESEARCH article
Front. Plant Sci.
Sec. Plant Pathogen Interactions
Volume 16 - 2025 | doi: 10.3389/fpls.2025.1627531
This article is part of the Research TopicUnraveling Molecular Mechanisms of Citrus Resistance to HuanglongbingView all 5 articles
The genetic architecture of gene expression regulation in a Citrus x Poncirus hybrid tolerant to Huanglongbing
Provisionally accepted
- 1University of California, Riverside, Riverside, United States
- 2U.S. Horticultural Research Laboratory, Agricultural Research Service, United States Department of Agriculture, Ft. Pierce, FL, Ft. Pierce, FL, United States
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Interspecific hybridization is a common and effective strategy for producing disease resilient citrus cultivars, including those with tolerance to Huanglongbing (HLB) disease. Several HLBtolerant cultivars have been developed through hybridization of mandarins (Citrus reticulata) with their wild relative Poncirus trifoliata. One such cultivar, 'US-897', exhibits robust tolerance to the bacteria causing HLB disease, Candidatus Liberibacter asiaticus (CLas). To explore the genetic architecture of the early transcriptional response to Candidatus Liberibacter asiaticus (CLas) infection in US-897, we performed transcriptomic analysis of the hybrid and its parents, 'Cleopatra' (C. reticulata) and 'Flying Dragon' (P. trifoliata). A haplotype-resolved genome for 'US-897' was generated using PacBio HiFi sequencing reads to support quantification of the expression of both the Citrus and Poncirus alleles. By profiling gene expression in this parentoffspring trio, we were able to determine the mode of inheritance for genes differentially expressed between parents ('Cleopatra' and 'Flying Dragon') and their interspecific hybrid ('US-897'), with the majority genes exhibiting non-additive patterns of gene expression inheritance.Additionally, analysis of allele-specific expression in the hybrid 'US-897' revealed the contribution of cis-versus trans-acting regulatory variants on genes with additive and nonadditive modes of inheritance. A strong correlation between differential expression between parents and allele-specific expression in 'US-897' suggests that cis-regulatory variation is a significant source of expression divergence between species. Finally, genes responsive to infection with CLas were identified to explore how gene regulation associated with tolerance to HLB was rewired between Citrus and its relative Poncirus.
Keywords: Citrus, Poncirus, Huanglongbing, Allele-specific expression (ASE), cis-regulation
Received: 12 May 2025; Accepted: 31 Jul 2025.
Copyright: © 2025 Diaz, Zayed, Ávila de Dios, Jiang, Bowman and Seymour. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Danelle K Seymour, University of California, Riverside, Riverside, United States
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