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Pandey SS, Li J, Oswalt C, Wang N. Dynamics of ' Candidatus Liberibacter asiaticus' Growth, Concentrations of Reactive Oxygen Species, and Ion Leakage in Huanglongbing-Positive Sweet Orange. PHYTOPATHOLOGY 2024; 114:961-970. [PMID: 38478730 DOI: 10.1094/phyto-08-23-0294-kc] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2024]
Abstract
Citrus Huanglongbing (HLB) caused by 'Candidatus Liberibacter asiaticus' (CLas) is the most devastating citrus disease worldwide. CLas induces systemic and chronic reactive oxygen species (ROS) production, which has been suggested to be a primary cause of cell death in phloem tissues and subsequent HLB symptoms. Mitigating oxidative stress caused by CLas using horticultural approaches has been suggested as a useful strategy to reduce HLB damages. To provide information regarding the application timing to mitigate ROS, we investigated monthly dynamics of CLas concentration, CLas-triggered ROS, and phloem cell death in the bark tissues of asymptomatic and symptomatic branches of HLB-positive Hamlin and Valencia sweet orange trees in the field. Healthy branches in the screenhouse were used as controls. CLas concentration exhibited significant variations over the course of the year, with two distinct peaks observed in Florida citrus groves-late spring/early summer and late fall. Within both Hamlin and Valencia asymptomatic tissues, CLas concentration demonstrated a negative correlation with the deviation between the monthly average mean temperature and the optimal temperature for CLas colonization in plants (25.7°C). However, such a correlation was not evident in symptomatic tissues of Hamlin or Valencia sweet oranges. ROS levels were consistently higher in symptomatic or asymptomatic branches than in healthy branches in most months. ROS concentrations were higher in symptomatic branches than in asymptomatic branches in most months. CLas triggered significant increases in ion leakage in most months for asymptomatic and symptomatic branches compared with healthy controls. In asymptomatic branches of Hamlin, a positive correlation was observed between CLas concentration and ROS concentrations, CLas concentration and ion leakage levels, as well as ROS and ion leakage. Intriguingly, such a relationship was not observed in Valencia asymptomatic branches or in the symptomatic branches of Hamlin and Valencia. This study sheds light on the pathogenicity of CLas by providing useful information on the temporal dynamics of ROS production, phloem cell death, and CLas growth, as well as provides useful information in determining the timing for application of antioxidants and antimicrobial agents to control HLB.
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Affiliation(s)
- Sheo Shankar Pandey
- Citrus Research and Education Center (CREC), Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL 33850, U.S.A
- Current affiliation: Life Sciences Division, Institute of Advanced Study in Science and Technology (IASST), Guwahati 781035, India
| | - Jinyun Li
- Citrus Research and Education Center (CREC), Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL 33850, U.S.A
| | - Chris Oswalt
- Institute of Food and Agricultural Sciences, University of Florida, Bartow, FL 33830, U.S.A
| | - Nian Wang
- Citrus Research and Education Center (CREC), Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL 33850, U.S.A
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Volpe HXL, Carmo-Sousa M, Luvizotto RAG, de Freitas R, Esperança V, Darolt JC, Pegoraro AAL, Magalhães DM, Favaris AP, Wulff NA, Miranda MP, Bento JMS, Leal WS. The greening-causing agent alters the behavioral and electrophysiological responses of the Asian citrus psyllid to a putative sex pheromone. Sci Rep 2024; 14:455. [PMID: 38172384 PMCID: PMC10764743 DOI: 10.1038/s41598-023-50983-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Accepted: 12/28/2023] [Indexed: 01/05/2024] Open
Abstract
The Asian Citrus Psyllid (ACP), Diaphorina citri, is a vector of the pathological bacterium Candidatus Liberibacter asiaticus (CLas), which causes the most devastating disease to the citrus industry worldwide, known as greening or huanglongbing (HLB). Earlier field tests with an acetic acid-based lure in greening-free, 'Valencia' citrus orange groves in California showed promising results. The same type of lures tested in São Paulo, Brazil, showed unsettling results. During the unsuccessful trials, we noticed a relatively large proportion of females in the field, ultimately leading us to test field-collected males and females for Wolbachia and CLas. The results showed high rates of Wolbachia and CLas infection in field populations. We then compared the olfactory responses of laboratory-raised, CLas-free, and CLas-infected males to acetic acid. As previously reported, CLas-uninfected males responded to acetic acid at 1 µg. Surprisingly, CLas-infected males required 50 × higher doses of the putative sex pheromone, thus explaining the failure to capture CLas-infected males in the field. CLas infection was also manifested in electrophysiological responses. Electroantennogram responses from CLas-infected ACP males were significantly higher than those obtained with uninfected males. To the best of our knowledge, this is the first report of a pathogen infection affecting a vector's response to a sex attractant.
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Affiliation(s)
- Haroldo X L Volpe
- Research and Development Department, Fund for Citrus Protection (Fundecitrus), Vila Melhado, Araraquara, São Paulo, 14807-040, Brazil
| | - Michele Carmo-Sousa
- Research and Development Department, Fund for Citrus Protection (Fundecitrus), Vila Melhado, Araraquara, São Paulo, 14807-040, Brazil
| | - Rejane A G Luvizotto
- Research and Development Department, Fund for Citrus Protection (Fundecitrus), Vila Melhado, Araraquara, São Paulo, 14807-040, Brazil
| | - Renato de Freitas
- Research and Development Department, Fund for Citrus Protection (Fundecitrus), Vila Melhado, Araraquara, São Paulo, 14807-040, Brazil
| | - Victoria Esperança
- Research and Development Department, Fund for Citrus Protection (Fundecitrus), Vila Melhado, Araraquara, São Paulo, 14807-040, Brazil
| | - Josiane C Darolt
- Research and Development Department, Fund for Citrus Protection (Fundecitrus), Vila Melhado, Araraquara, São Paulo, 14807-040, Brazil
| | - Abner A L Pegoraro
- Research and Development Department, Fund for Citrus Protection (Fundecitrus), Vila Melhado, Araraquara, São Paulo, 14807-040, Brazil
| | - Diego M Magalhães
- Department of Entomology and Acarology, Luiz de Queiroz College of Agriculture, University of São Paulo (USP), Piracicaba, São Paulo, 13418-900, Brazil
| | - Arodi P Favaris
- Department of Entomology and Acarology, Luiz de Queiroz College of Agriculture, University of São Paulo (USP), Piracicaba, São Paulo, 13418-900, Brazil
| | - Nelson A Wulff
- Research and Development Department, Fund for Citrus Protection (Fundecitrus), Vila Melhado, Araraquara, São Paulo, 14807-040, Brazil
| | - Marcelo P Miranda
- Research and Development Department, Fund for Citrus Protection (Fundecitrus), Vila Melhado, Araraquara, São Paulo, 14807-040, Brazil
| | - José Maurício S Bento
- Department of Entomology and Acarology, Luiz de Queiroz College of Agriculture, University of São Paulo (USP), Piracicaba, São Paulo, 13418-900, Brazil
| | - Walter S Leal
- Department of Molecular and Cellular Biology, University of California-Davis, Davis, CA, 95616, USA.
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