Lemon production faces growing threats from citrus yellow vein clearing virus (CYVCV), a disease that causes vein necrosis, leaf drop, and significant yield losses. Despite recognizing the virus's basic genetic structure, little is known about how host plants can naturally defend themselves. Previous studies suggested some host proteins could interact with viral components, but comprehensive mechanisms remained elusive. Moreover, systemic acquired resistance (SAR), crucial for plant immunity, was mainly associated with bacterial and fungal threats, not viral infections. Based on these challenges, there is an urgent need to explore how specific genes or metabolic pathways might strengthen lemon plants' defenses against viral invasion.
A research team from the Citrus Research Institute at Southwest University published a study (DOI: 10.1093/hr/uhae287) on October 11, 2024, in Horticulture Research that reveals the antiviral role of the gene ClGDPD1 in Eureka lemon. The researchers demonstrated that ClGDPD1 interacts directly with the virus's coat protein (CP), enhances glycerophospholipid metabolism, and significantly elevates G3P accumulation, thereby boosting resistance to CYVCV. Their findings offer novel insights into the molecular mechanisms of citrus defense and highlight ClGDPD1 as a valuable target for future breeding programs aimed at developing virus-resistant lemon varieties.
The study showed that ClGDPD1 expression was highly upregulated upon CYVCV infection and localized to the membrane and endoplasmic reticulum, where it directly interacted with the virus's coat protein (CP). Through various molecular assays—including yeast two-hybrid, pull-down, BiFC, and luciferase imaging—the researchers confirmed the physical interaction between ClGDPD1 and CP. Overexpression of ClGDPD1 not only suppressed CP accumulation but also enhanced the expression of genes involved in glycerophospholipid metabolism, resulting in elevated levels of G3P and related metabolites such as GPDH, PLA2, and PC. Transgenic Eureka lemon plants overexpressing ClGDPD1 exhibited markedly reduced viral titers and only mild disease symptoms after viral challenge. Furthermore, exogenous glycerol treatments, which mimic G3P accumulation, similarly enhanced resistance, validating the protective role of G3P. Transcriptome profiling further indicated that defense pathways, such as MAPK signaling and systemic acquired resistance (SAR), were activated in ClGDPD1 transgenic lines. These results highlight ClGDPD1 as a critical regulatory hub connecting lipid metabolism to antiviral defense in citrus plants.
"Our study demonstrates that manipulating glycerophospholipid metabolism, specifically through ClGDPD1-mediated G3P accumulation, can effectively enhance lemon resistance to viral infection," said lead researcher Dr. Yan Zhou. "This discovery not only deepens our understanding of plant-virus interactions but also offers tangible strategies for developing virus-resistant citrus varieties. Moving forward, we plan to investigate how these findings can be applied in field conditions to mitigate yield losses caused by CYVCV and potentially other viral threats."
The findings offer practical solutions for combating citrus yellow vein clearing virus in commercial lemon orchards. By engineering or breeding lemon varieties with higher ClGDPD1 expression or by applying glycerol treatments to stimulate G3P accumulation, farmers could significantly reduce disease incidence and crop losses. Moreover, the study's insights into the relationship between lipid metabolism and systemic immunity could be extended to other fruit crops facing viral threats. This work also establishes a foundation for exploring glycerophospholipid metabolic engineering as a general strategy to enhance broad-spectrum disease resistance in plants, ultimately contributing to more sustainable and resilient agricultural systems.
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References
DOI
10.1093/hr/uhae287
Original Source URL
https://doi.org/10.1093/hr/uhae287
Funding information
This research was partially supported by China Agriculture Research System of MOF and MARA (CARS-26-05B) and Overseas Expertise Introduction Project for Discipline Innovation, Ministry of Education of the People's Republic of China (CN) (B18044).
About Horticulture Research
Horticulture Research is an open access journal of Nanjing Agricultural University and ranked number one in the Horticulture category of the Journal Citation Reports ™ from Clarivate, 2023. The journal is committed to publishing original research articles, reviews, perspectives, comments, correspondence articles and letters to the editor related to all major horticultural plants and disciplines, including biotechnology, breeding, cellular and molecular biology, evolution, genetics, inter-species interactions, physiology, and the origination and domestication of crops.