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Zuo S, Xu L, Zhang H, Jiang M, Wu S, Zhang LH, Zhou X, Wang J. FlgI Is a Sec-Dependent Effector of Candidatus Liberibacter asiaticus That Can Be Blocked by Small Molecules Identified Using a Yeast Screen. Plants (Basel) 2024; 13:318. [PMID: 38276775 PMCID: PMC10819201 DOI: 10.3390/plants13020318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Revised: 01/11/2024] [Accepted: 01/16/2024] [Indexed: 01/27/2024]
Abstract
Huanglongbing (HLB) is one of the most devastating diseases of citrus worldwide. The phloem-restricted bacterium Candidatus Liberibacter asiaticus (CLas) is considered to be the main pathogen responsible for HLB. There is currently no effective practical strategy for the control of HLB. Our understanding of how pathogens cause HLB is limited because CLas has not been artificially cultured. In this study, 15 potential virulence factors were predicted from the proteome of CLas through DeepVF and PHI-base searches. One among them, FlgI, was found to inhibit yeast growth when expressed in Saccharomyces cerevisiae. The expression of the signal peptide of FlgI fused with PhoA in Escherichia coli resulted in the discovery that FlgI was a novel Sec-dependent secretory protein. We further found that the carboxyl-terminal HA-tagged FlgI was secreted via outer membrane vesicles in Sinorhizobium meliloti. Fluoresence localization of transient expression FlgI-GFP in Nicotiana benthamiana revealed that FlgI is mainly localized in the cytoplasm, cell periphery, and nuclear periphery of tobacco cells. In addition, our experimental results suggest that FlgI has a strong ability to induce callose deposition and cell necrosis in N. benthamiana. Finally, by screening a large library of compounds in a high-throughput format, we found that cyclosporin A restored the growth of FlgI-expressing yeast. These results confirm that FlgI is a novel Sec-dependent effector, enriching our understanding of CLas pathogenicity and helping to develop new and more effective strategies to manage HLB.
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Affiliation(s)
| | | | | | | | | | | | - Xiaofan Zhou
- Integrative Microbiology Research Centre, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou 510642, China; (S.Z.); (L.X.); (H.Z.); (M.J.); (S.W.); (L.-H.Z.)
| | - Junxia Wang
- Integrative Microbiology Research Centre, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou 510642, China; (S.Z.); (L.X.); (H.Z.); (M.J.); (S.W.); (L.-H.Z.)
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2
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Dou S, Wang L, Fan D, Miao L, Yan J, He H. Classification of Citrus Huanglongbing Degree Based on CBAM-MobileNetV2 and Transfer Learning. Sensors (Basel) 2023; 23:5587. [PMID: 37420753 DOI: 10.3390/s23125587] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2023] [Revised: 06/11/2023] [Accepted: 06/13/2023] [Indexed: 07/09/2023]
Abstract
Citrus has become a pivotal industry for the rapid development of agriculture and increasing farmers' incomes in the main production areas of southern China. Knowing how to diagnose and control citrus huanglongbing has always been a challenge for fruit farmers. To promptly recognize the diagnosis of citrus huanglongbing, a new classification model of citrus huanglongbing was established based on MobileNetV2 with a convolutional block attention module (CBAM-MobileNetV2) and transfer learning. First, the convolution features were extracted using convolution modules to capture high-level object-based information. Second, an attention module was utilized to capture interesting semantic information. Third, the convolution module and attention module were combined to fuse these two types of information. Last, a new fully connected layer and a softmax layer were established. The collected 751 citrus huanglongbing images, with sizes of 3648 × 2736, were divided into early, middle, and late leaf images with different disease degrees, and were enhanced to 6008 leaf images with sizes of 512 × 512, including 2360 early citrus huanglongbing images, 2024 middle citrus huanglongbing images, and 1624 late citrus huanglongbing images. In total, 80% and 20% of the collected citrus huanglongbing images were assigned to the training set and the test set, respectively. The effects of different transfer learning methods, different model training effects, and initial learning rates on model performance were analyzed. The results show that with the same model and initial learning rate, the transfer learning method of parameter fine tuning was obviously better than the transfer learning method of parameter freezing, and that the recognition accuracy of the test set improved by 1.02~13.6%. The recognition accuracy of the citrus huanglongbing image recognition model based on CBAM-MobileNetV2 and transfer learning was 98.75% at an initial learning rate of 0.001, and the loss value was 0.0748. The accuracy rates of the MobileNetV2, Xception, and InceptionV3 network models were 98.14%, 96.96%, and 97.55%, respectively, and the effect was not as significant as that of CBAM-MobileNetV2. Therefore, based on CBAM-MobileNetV2 and transfer learning, an image recognition model of citrus huanglongbing images with high recognition accuracy could be constructed.
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Affiliation(s)
- Shiqing Dou
- College of Geomatics and Geoinformation, Guilin University of Technology, Guilin 541006, China
- Ecological Spatiotemporal Big Data Perception Service Laboratory, Guilin University of Technology, Guilin 541006, China
| | - Lin Wang
- College of Geomatics and Geoinformation, Guilin University of Technology, Guilin 541006, China
- Ecological Spatiotemporal Big Data Perception Service Laboratory, Guilin University of Technology, Guilin 541006, China
| | - Donglin Fan
- College of Geomatics and Geoinformation, Guilin University of Technology, Guilin 541006, China
- Ecological Spatiotemporal Big Data Perception Service Laboratory, Guilin University of Technology, Guilin 541006, China
| | - Linlin Miao
- College of Geomatics and Geoinformation, Guilin University of Technology, Guilin 541006, China
- Ecological Spatiotemporal Big Data Perception Service Laboratory, Guilin University of Technology, Guilin 541006, China
| | - Jichi Yan
- College of Mechanical and Control Engineering, Guilin University of Technology, Guilin 541006, China
| | - Hongchang He
- College of Geomatics and Geoinformation, Guilin University of Technology, Guilin 541006, China
- Ecological Spatiotemporal Big Data Perception Service Laboratory, Guilin University of Technology, Guilin 541006, China
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Wu F, Liu L, Fox EGP, Deng X, Xu M, Zheng Z, Li X, Fu J, Zhu H, Huang J, Deng T. Physiological Variables Influenced by ' Candidatus Liberibacter asiaticus' Infection in Two Citrus Species. Plant Dis 2023:PDIS08221747RE. [PMID: 36399004 DOI: 10.1094/pdis-08-22-1747-re] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
'Candidatus Liberibacter asiaticus' is the bacterium associated with the citrus disease known as huanglongbing (HLB). This study evaluated the influence of 'Ca. L. asiaticus' infection on a number of key plant physiological variables concerning photosynthesis, cell integrity, reactive oxygen species scavengers' activity, and osmoregulation of two different species of citrus-the pomelo Citrus maxima and the mandarin C. reticulata 'Tankan'-relative to their measured 'Ca. L. asiaticus' infection load. Results indicated that all measured physiological variables except soluble sugar were affected by increased 'Ca. L. asiaticus' infection titers, wherein the variety C. maxima proved overall more resistant than C. reticulata. 'Ca. L. asiaticus' infection was linked in both plants to decrease in chlorophyll concentration, cell membrane permeability, and malondialdehyde, as well as increased free proline and starch contents. Chlorophyll fluorescence measurements taken 9 months after grafting the mandarin C. reticulata with 'Ca. L. asiaticus' scions revealed a significant decrease in the photosynthesis variables maximum photochemical quantum yield of photosystem II (PSII), effective photochemical quantum yield of PSII, and coefficient of photochemical fluorescence quenching assuming interconnected PSII antennae, whereas nonphotochemical fluorescence quenching increased significantly; C. maxima plants, on the other hand, did not show significant differences until the 12th month from infection exposure. The variables superoxide dismutase, catalase, peroxidase, and soluble protein initially increased and later decreased. In addition, progression of 'Ca. L. asiaticus' replication in both citrus species was accompanied by rapid changes in three reactive oxygen species scavenging enzymes in C. maxima, while the pattern was different in C. reticulata. We hypothesize that the observed interspecific differences in physiological change are related to their relative resistance against 'Ca. L. asiaticus' infection. These results provide a scaffold for better describing the pathogenesis, selecting the most resistant breeds, or even validating pertaining omics research; ultimately, these detailed observations can facilitate the diagnosis of 'Ca. L. asiaticus' infection.
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Affiliation(s)
- Fengnian Wu
- School of Life Sciences and Food Engineering, Hanshan Normal University, Chaozhou 521041, China
| | - Lihui Liu
- Guangxi Key Laboratory of Biology for Crop Diseases and Insect Pests/Plant Protection Research Institute, Guangxi Academy of Agricultural Sciences, Nanning 530007, China
| | - Eduardo G P Fox
- Programa de Pós-Graduação em Ambiente e Sociedade (PPGAS), Universidade Estadual de Goiás (UEG), Goiás 75860-000, Brazil
| | - Xiaoling Deng
- Citrus Huanglongbing Research Laboratory, South China Agricultural University, Guangzhou 510642, China
| | - Meirong Xu
- Citrus Huanglongbing Research Laboratory, South China Agricultural University, Guangzhou 510642, China
| | - Zheng Zheng
- Citrus Huanglongbing Research Laboratory, South China Agricultural University, Guangzhou 510642, China
| | - Xiuhong Li
- School of Life Sciences and Food Engineering, Hanshan Normal University, Chaozhou 521041, China
| | - Jiawei Fu
- School of Life Sciences and Food Engineering, Hanshan Normal University, Chaozhou 521041, China
| | - Hui Zhu
- School of Life Sciences and Food Engineering, Hanshan Normal University, Chaozhou 521041, China
| | - Jianjian Huang
- School of Life Sciences and Food Engineering, Hanshan Normal University, Chaozhou 521041, China
| | - Tiejun Deng
- Guangxi Key Laboratory of Biology for Crop Diseases and Insect Pests/Plant Protection Research Institute, Guangxi Academy of Agricultural Sciences, Nanning 530007, China
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Du J, Wang Q, Shi H, Zhou C, He J, Wang X. A prophage-encoded effector from "Candidatus Liberibacter asiaticus" targets ASCORBATE PEROXIDASE6 in citrus to facilitate bacterial infection. Mol Plant Pathol 2023; 24:302-316. [PMID: 36692022 PMCID: PMC10013806 DOI: 10.1111/mpp.13296] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2022] [Revised: 01/03/2023] [Accepted: 01/03/2023] [Indexed: 05/21/2023]
Abstract
Citrus huanglongbing (HLB), associated with the unculturable phloem-limited bacterium "Candidatus Liberibacter asiaticus" (CLas), is the most devastating disease in the citrus industry worldwide. However, the pathogenicity of CLas remains poorly understood. In this study, we show that AGH17488, a secreted protein encoded by the prophage region of the CLas genome, suppresses plant immunity via targeting the host ASCORBATE PEROXIDASE6 (APX6) protein in Nicotiana benthamiana and Citrus sinensis. The transient expression of AGH17488 reduced the chloroplast localization of APX6 and its enzyme activity, inhibited the accumulation of reactive oxygen species (H2 O2 and O2 - ) and the lipid oxidation endproduct malondialdehyde in plants, and promoted the proliferation of Pseudomonas syringae pv. tomato DC3000 and Xanthomonas citri subsp. citri. This study reveals a novel mechanism underlying how CLas uses a prophage-encoded effector, AGH17488, to target a reactive oxygen species accumulation-related gene, APX6, in the host to facilitate its infection.
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Affiliation(s)
- Jiao Du
- National Citrus Engineering Research CenterCitrus Research Institute, Southwest UniversityChongqingChina
- Fruit Tree and Melon Information Research CenterZhengzhou Fruit Research Institute, Chinese Academy of Agricultural SciencesZhengzhouChina
| | - Qiying Wang
- National Citrus Engineering Research CenterCitrus Research Institute, Southwest UniversityChongqingChina
| | - Hongwei Shi
- National Citrus Engineering Research CenterCitrus Research Institute, Southwest UniversityChongqingChina
| | - Changyong Zhou
- National Citrus Engineering Research CenterCitrus Research Institute, Southwest UniversityChongqingChina
| | - Jun He
- National Citrus Engineering Research CenterCitrus Research Institute, Southwest UniversityChongqingChina
| | - Xuefeng Wang
- National Citrus Engineering Research CenterCitrus Research Institute, Southwest UniversityChongqingChina
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Li J, He P, He P, Li Y, Wu Y, Lu Z, Li X, Yang Y, Wang Y, Guo J, Munir S, He Y. Potential of citrus endophyte Bacillus subtilis L1-21 in the control of Candidatus Liberibacter asiaticus in Asian citrus psyllid, Diaphorina citri. Pest Manag Sci 2022; 78:5164-5171. [PMID: 36114796 DOI: 10.1002/ps.7134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 08/08/2022] [Accepted: 08/18/2022] [Indexed: 06/15/2023]
Abstract
BACKGROUND Asian citrus psyllid (ACP), also known as Diaphorina citri, is the natural vector of Candidatus Liberibacter asiaticus (CLas), which is responsible for Huanglongbing (HLB), a devastating citrus disease. Previously, the pathogen was successfully excluded from diseased citrus plants by using the indigenous endophyte Bacillus subtilis L1-21. However, the pathogen elimination and colonization potential of B. subtilis L1-21 in the carrier vector ACP, as well as the recruitment of native microbial communities of psyllid in the presence of endophytes, are still unknown. RESULTS Initially, we suggested that endophyte L1-21 reduced the CLas copies in ACP from 6.58 × 106 to 5.04 × 104 per insect after 48 h, however, the pathogen copies remained stable in the negative control. The endophyte was stable for 48 h after application. Among the bacterial genera those highlighted in ACP were Candidatus Liberibacter, Pseudomonas, Candidatus Profftella, Methylobacterium-Methylorubrum, Pantoea, Curtobacterium, Wolbachia, Actinomycetospora, and Bacillus. Interestingly, B. subtilis L1-21 easily colonizes the midgut of ACP but cannot be detected in eggs. When ACP with endophyte L1-21 was allowed to feed on new citrus leaves, the highest colonization was observed. We also found that psyllids carrying endophyte L1-21 after feeding on citrus leaves reduced the CLas copies in leaves on the 0, 3rd and 5th day from 8.18 × 10,4 2.6 × 10,3 and 0 pathogen copies/g fresh midvein, respectively. CONCLUSIONS We propose that B. subtilis L1-21 is a native endophyte in citrus and psyllid, which efficiently reduces the CLas pathogen in both citrus and psyllids, provides a more protective effect by increasing the number of cultivable endophytes, and successfully colonizes the midgut of ACP. © 2022 Society of Chemical Industry.
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Affiliation(s)
- Jian Li
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan Agricultural University, Kunming, China
| | - Pengfei He
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan Agricultural University, Kunming, China
| | - Pengbo He
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan Agricultural University, Kunming, China
| | - Yongmei Li
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan Agricultural University, Kunming, China
| | - Yixin Wu
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan Agricultural University, Kunming, China
| | - Zhanjun Lu
- College of Life Sciences, Gannan Normal University, Ganzhou, China
| | - Xingyu Li
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan Agricultural University, Kunming, China
| | - Yongchao Yang
- College of Biological and Agricultural Sciences, Honghe University, Mengzi, China
| | - Yuehu Wang
- Key Laboratory of Economic Plants and Biotechnology, Kunming Institute of Botany, Chinese Academy of Sciences (CAS), Kunming, China
| | - Jun Guo
- Institute of Tropical and Subtropical Cash Crops, Yunnan Academy of Agricultural Sciences, Baoshan, China
| | - Shahzad Munir
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan Agricultural University, Kunming, China
| | - Yueqiu He
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan Agricultural University, Kunming, China
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Hu Y, Meng Y, Yao L, Wang E, Tang T, Wang Y, Dai L, Zhao M, Zhang HE, Fan X, Luo L, Xiang W, Zhang Z. Citrus Huanglongbing correlated with incidence of Diaphorina citri carrying Candidatus Liberibacter asiaticus and citrus phyllosphere microbiome. Front Plant Sci 2022; 13:964193. [PMID: 36466264 PMCID: PMC9716883 DOI: 10.3389/fpls.2022.964193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Accepted: 10/05/2022] [Indexed: 06/17/2023]
Abstract
In China, citrus Huanglongbing (HLB) disease is caused by the Candidatus Liberibacter asiaticus bacterium, which is carried by the Asian citrus psyllid Diaphorina citri Kuwayama. It was hypothesized that the epidemic of the HLB may related with the rate of bacterium presence in the insect vector and bacterium content in plant tissues, as well as the phyllosphere microbe communities changes. This study systematically analyzed the presence or absence of Ca. L. asiaticus in citrus tree leaves and in the insect vector D. citri over a 6-year period using real-time PCR. In addition, changes in the number of bacteria carried by D. citri over 12 months were quantified, as well as the relationship between the proportion of D. citri carrying Ca. L. asiaticus and the proportion of plants infected with Ca. L. asiaticus were analyzed. Results showed that the proportion of D. citri carrying bacteria was stable and relatively low from January to September. The bacteria in citrus leaves relatively low in spring and summer, then peaked in December. The proportion of D. citri carrying bacteria gradually declined from 2014 to 2019. The proportion of D. citri carrying Ca. L. asiaticus showed a significant positive correlation with the proportion of diseased citrus. The phyllosphere bacterial and fungal communities on the healthy citrus leaf were significantly different with the disease leaf in April and December. Pathogenic invasions change the citrus phyllosphere microbial community structure. It could be summarized that citrus Huanglongbing correlated with incidence of Diaphorina citri carrying Candidatus Liberibacter asiaticus and citrus phyllosphere microbiome.
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Affiliation(s)
- Yang Hu
- Department of Tree Breeding, Zhejiang Academy of Forestry, Hangzhou, China
| | - Youqing Meng
- Zhejiang Provincial General Station of Plant Protection, Quarantine and Pesticide Management, Hangzhou, China
| | - Liangjin Yao
- Department of Tree Breeding, Zhejiang Academy of Forestry, Hangzhou, China
| | - Enguo Wang
- Department of Plant Protection, Zhejiang Linhai Agricultural Technology Extension Center, Taizhou, China
| | - Tao Tang
- Hunan Plant Protection Institute, Hunan Academy of Agricultural Science, Changsha, China
| | - Yunsheng Wang
- College of Plant Protection, Hunan Agricultural University, Changsha, China
| | - Liangying Dai
- College of Plant Protection, Hunan Agricultural University, Changsha, China
| | - Mingping Zhao
- Plant Protection and Quarantine Station, Bureau of Agriculture and Rural Affairs of Jianghua Yao Autonomous County, Yongzhou, China
| | - Hong-en Zhang
- School of Mathematical, Nankai University, Tianjin, China
| | - Xiaoyan Fan
- Institute of Environmental Biotechnology, Graz University of Technology, Graz, Austria
| | - Luyun Luo
- School of Advanced Agriculture and Bioengineering, Yangtze Normal University, Chongqing, China
| | - Wei Xiang
- Hunan Crop Research Institute, Hunan Academy of Agricultural Science, Changsha, China
| | - Zhuo Zhang
- Hunan Plant Protection Institute, Hunan Academy of Agricultural Science, Changsha, China
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De Francesco A, Lovelace AH, Shaw D, Qiu M, Wang Y, Gurung F, Ancona V, Wang C, Levy A, Jiang T, Ma W. Transcriptome Profiling of ' Candidatus Liberibacter asiaticus' in Citrus and Psyllids. Phytopathology 2022; 112:116-130. [PMID: 35025694 DOI: 10.1094/phyto-08-21-0327-fi] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
'Candidatus Liberibacter asiaticus' (Las) is an emergent bacterial pathogen that is associated with the devastating citrus huanglongbing (HLB). Vectored by the Asian citrus psyllid, Las colonizes the phloem tissue of citrus, causing severe damage to infected trees. So far, cultivating pure Las culture in axenic media has not been successful, and dual-transcriptome analyses aiming to profile gene expression in both Las and its hosts have a low coverage of the Las genome because of the low abundance of bacterial RNA in total RNA extracts from infected tissues. Therefore, a lack of understanding of the Las transcriptome remains a significant knowledge gap. Here, we used a bacterial cell enrichment procedure and confidently determined the expression profiles of approximately 84% of the Las genes. Genes that exhibited high expression in citrus include transporters, ferritin, outer membrane porins, specific pilins, and genes involved in phage-related functions, cell wall modification, and stress responses. We also found 106 genes to be differentially expressed in citrus versus Asian citrus psyllids. Genes related to transcription or translation and resilience to host defense response were upregulated in citrus, whereas genes involved in energy generation and the flagella system were expressed to higher levels in psyllids. Finally, we determined the relative expression levels of potential Sec-dependent effectors, which are considered as key virulence factors of Las. This work advances our understanding of HLB biology and offers novel insight into the interactions of Las with its plant host and insect vector.
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Affiliation(s)
- Agustina De Francesco
- Department of Microbiology and Plant Pathology, University of California, Riverside, CA 92521, U.S.A
| | - Amelia H Lovelace
- The Sainsbury Laboratory, Norwich Research Park, NR4 7UH, United Kingdom
| | - Dipan Shaw
- Department of Computer Science and Engineering, University of California, Riverside, CA 92521, U.S.A
| | - Min Qiu
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China
| | - Yuanchao Wang
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China
| | - Fatta Gurung
- Citrus Center, Department of Agriculture, Agribusiness and Environmental Sciences, Texas A&M University-Kingsville, Weslaco, TX 78599, U.S.A
| | - Veronica Ancona
- Citrus Center, Department of Agriculture, Agribusiness and Environmental Sciences, Texas A&M University-Kingsville, Weslaco, TX 78599, U.S.A
| | - Chunxia Wang
- Citrus Research and Education Center, University of Florida, Lake Alfred, FL 33850, U.S.A
| | - Amit Levy
- Citrus Research and Education Center, University of Florida, Lake Alfred, FL 33850, U.S.A
| | - Tao Jiang
- Department of Computer Science and Engineering, University of California, Riverside, CA 92521, U.S.A
| | - Wenbo Ma
- Department of Microbiology and Plant Pathology, University of California, Riverside, CA 92521, U.S.A
- The Sainsbury Laboratory, Norwich Research Park, NR4 7UH, United Kingdom
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Zhang LH, Ren SL, Su ZQ, Xu PP, Ou D, Wang LJ, Sang W, Qiu BL. Impact of Huanglongbing Pathogen Infection on the Amino Acid Composition in Both Citrus Plants and the Asian Citrus Psyllid. Front Physiol 2021; 12:777908. [PMID: 34955890 PMCID: PMC8703012 DOI: 10.3389/fphys.2021.777908] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Accepted: 11/11/2021] [Indexed: 11/30/2022] Open
Abstract
The Asian citrus psyllid (ACP) Diaphorina citri is the main vector of the pathogen Candidatus Liberibacter asiaticus (CLas), which is the causal agent of citrus Huanglongbing disease. Feeding by both ACP nymphs and adults on host plants allows them to obtain nutrition. Therefore, the nutritional content within the plant phloem is of much importance for the development and reproduction of ACP. The infection by pathogenic microbiomes may affect the amino acid contents of their host plants and then indirectly affect the biology of sap-feeding insects. In this study, we investigated the amino acid contents and their proportions in both CLas-infected and CLas-free citrus plants, ACP adults, and also in honeydew produced by ACP nymphs. Results showed that infection by CLas had a large impact on the amino acid species and proportion in all the tested target plants, ACP adults, and in the honeydew of ACP nymphs. The content of total amino acids in CLas-infected citrus was much higher than that of CLas-free citrus. However, CLas infection significantly reduced the proportion of essential amino acids (EAAs) in these plants. When feeding on CLas-infected citrus plants, ACP adults absorbed less total amino acids than those adults feeding on healthy plants, but the proportion of EAAs was significantly higher when they fed on CLas-infected citrus plants. The proportion of EAAs also significantly increased in the honeydew secreted by ACP nymphs that fed on CLas-infected citrus plants. However, EAA detection in the honeydew of ACP nymphs indicated that the utilization rate of EAAs by CLas positive ACP nymphs was reduced. Our study has revealed that CLas infection significantly affects the contents, proportion, and utilization efficiency of different amino acids in citrus plants, ACP adults, and nymphs, leading to a developmental pattern of ACP that is more conducive to CLas transmission.
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Affiliation(s)
- Li-He Zhang
- Chongqing Key Laboratory of Vector Insects, College of Life Sciences, Chongqing Normal University, Chongqing, China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, China
- Guangdong Laboratory of Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, China
| | - Su-Li Ren
- Airport Management College, Guangzhou Civil Aviation College, Guangzhou, China
| | - Zheng-Qin Su
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, China
| | - Pei-Ping Xu
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, China
| | - Da Ou
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, China
| | - Li-Jun Wang
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, China
| | - Wen Sang
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, China
| | - Bao-Li Qiu
- Chongqing Key Laboratory of Vector Insects, College of Life Sciences, Chongqing Normal University, Chongqing, China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, China
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Li X, Ruan H, Zhou C, Meng X, Chen W. Controlling Citrus Huanglongbing: Green Sustainable Development Route Is the Future. Front Plant Sci 2021; 12:760481. [PMID: 34868155 PMCID: PMC8636133 DOI: 10.3389/fpls.2021.760481] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Accepted: 10/06/2021] [Indexed: 05/12/2023]
Abstract
Huanglongbing (HLB) is the most severe bacterial disease of citrus crops caused by Candidatus Liberibacter spp. It causes a reduction in fruit yield, poor fruit quality, and even plants death. Due to the lack of effective medicine, HLB is also called citrus "AIDS." Currently, it is essential for the prevention and control of HLB to use antibiotics and pesticides while reducing the spread of HLB by cultivating pathogen-free seedlings, removing disease trees, and killing Asian citrus psyllid (ACP). New compounds [e.g., antimicrobial peptides (AMPs) and nanoemulsions] with higher effectiveness and less toxicity were also found and they have made significant achievements. However, further evaluation is required before these new antimicrobial agents can be used commercially. In this review, we mainly introduced the current strategies from the aspects of physical, chemical, and biological and discussed their environmental impacts. We also proposed a green and ecological strategy for controlling HLB basing on the existing methods and previous research results.
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Affiliation(s)
- Xue Li
- MOE Key Laboratory of Laser Life Science, Institute of Laser Life Science, Guangzhou, China
- Guangdong Provincial Key Laboratory of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou, China
| | - Huaqin Ruan
- State Key Laboratory of Biocontrol and Guangdong Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Chengqian Zhou
- Neuroscience Laboratory, Hugo Moser Research Institute at Kennedy Krieger, Baltimore, MD, United States
| | - Xiangchun Meng
- Key Laboratory of South Subtropical Fruit Biology and Genetic Resource Utilization (MOA), Guangzhou, China
- Key Laboratory of Tropical and Subtropical Fruit Tree Research, Guangzhou, China
- Institute of Fruit Tree Research, Guangdong Academy of Agricultural Science, Guangzhou, China
| | - Wenli Chen
- MOE Key Laboratory of Laser Life Science, Institute of Laser Life Science, Guangzhou, China
- Guangdong Provincial Key Laboratory of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou, China
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10
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Fang F, Guo H, Zhao A, Li T, Liao H, Deng X, Xu M, Zheng Z. A Significantly High Abundance of " Candidatus Liberibacter asiaticus" in Citrus Fruit Pith: in planta Transcriptome and Anatomical Analyses. Front Microbiol 2021; 12:681251. [PMID: 34177866 PMCID: PMC8225937 DOI: 10.3389/fmicb.2021.681251] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Accepted: 05/10/2021] [Indexed: 11/20/2022] Open
Abstract
Huanglongbing, a highly destructive disease of citrus, is associated with the non-culturable phloem-limited α-proteobacterium "Candidatus Liberibacter asiaticus" (CLas). The distribution patterns of CLas in infected plant are variable and not consistent, which make the CLas detection and characterization more challenging. Here, we performed a systemic analysis of CLas distribution in citrus branches and fruits of 14 cultivars. A significantly high concentration of CLas was detected in fruit pith (dorsal vascular bundle) of 14 citrus cultivars collected at fruit maturity season. A 2-year monitoring assay of CLas population in citrus branches of "Shatangju" mandarin (Citrus reticulata Blanco "Shatangju") revealed that CLas population already exhibited a high level even before the appearance of visual symptoms in the fruit rind. Quantitative analyses of CLas in serial 1.5-cm segments of fruit piths showed the CLas was unevenly distributed within fruit pith and tended to colonize in the middle or distal (stylar end) regions of pith. The use of CLas-abundant fruit pith for dual RNA-seq generated higher-resolution CLas transcriptome data compared with the leaf samples. CLas genes involved in transport system, flagellar assembly, lipopolysaccharide biosynthesis, virulence, stress response, and cell surface structure, as well as host genes involved in biosynthesis of antimicrobial-associated secondary metabolites, was up-regulated in leaf midribs compared with fruit pith. In addition, CLas infection caused the severe collapse in phloem and callose deposition in the plasmodesmata of fruit pith. The ability of fruit pith to support multiplication of CLas to high levels makes it an ideal host tissue for morphological studies and in planta transcriptome analyses of CLas-host interactions.
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Affiliation(s)
- Fang Fang
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou, China
| | - Hengyu Guo
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou, China
| | - Anmin Zhao
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou, China
| | - Tao Li
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou, China
| | - Huihong Liao
- Horticulture Research Institute, Guangxi Academy of Agricultural Sciences, Nanning, China
| | - Xiaoling Deng
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou, China
| | - Meirong Xu
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou, China
| | - Zheng Zheng
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou, China
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11
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Zheng Y, Guo J, Deng X, Zheng Z. Genome Sequence Resource of ' Candidatus Liberibacter asiaticus' Strain Myan16 from Myanmar. Plant Dis 2021; 105:1162-1164. [PMID: 33044146 DOI: 10.1094/pdis-08-20-1841-a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
'Candidatus Liberibacter asiaticus,' an uncultured α-proteobacterium, is associated with citrus huanglongbing (HLB, yellow shoot disease), a destructive disease threatening citrus production worldwide. Here, we reported the draft genome sequence of 'Ca. L. asiaticus' strain Myan16 from an HLB-affected lime tree in Myitkyina, Kachin State, Myanmar. The strain Myan16 genome is 1,229,102 bp with an average G+C content of 36.4%, along with a circular prophage: P-Myan16-2 (36,303 bp, type 2). This is the first genome sequence of a 'Ca. L. asiaticus' strain from Myanmar, which will enrich the current 'Ca. L. asiaticus' genome sequence database and facilitate HLB epidemiology research in Asia and world.
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Affiliation(s)
- Yongqin Zheng
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou, China
| | - Jun Guo
- Institute of Tropical and Subtropical Cash Crops, Yunnan Academy of Agricultural Sciences, Baoshan, Yunnan, China
| | - Xiaoling Deng
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou, China
| | - Zheng Zheng
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou, China
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12
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Wang Y, Kondo T, He Y, Zhou Z, Lu J. Genome Sequence Resource of ' Candidatus Liberibacter asiaticus' from Diaphorina citri Kuwayama (Hemiptera: Liviidae) in Colombia. Plant Dis 2021; 105:193-195. [PMID: 32729808 DOI: 10.1094/pdis-06-20-1249-a] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
'Candidatus Liberibacter asiaticus' (CLas) is an unculturable phloem-restricted α-proteobacterium associated with huanglongbing (HLB). Here, we provide the genome sequence of CLas strain CoFLP1 from its insect vector Diaphorina citri (Hemiptera: Liviidae) collected in the department of La Guajira, Colombia. The CoFLP1 strain is composed of 1,231,639 bp with G+C 36.5% content. This study reports the first CLas genome sequence from Colombia, which will add to CLas genome resources and help to elucidate our understanding of the introduction pathway of HLB in South America.
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Affiliation(s)
- Yanjing Wang
- College of Agriculture and Food Sciences, Zhejiang Agriculture & Forestry University, Lin'an, Zhejiang 200300, China
| | - Takumasa Kondo
- Corporación Colombiana de Investigación Agropecuaria (AGROSAVIA), Laboratorio de Entomología, Centro de Investigación Palmira, Colombia
| | - Yurong He
- Department of Entomology, South China Agricultural University, Guangzhou, Guangdong 510642, China
| | - Zhuohuai Zhou
- College of Agriculture and Food Sciences, Zhejiang Agriculture & Forestry University, Lin'an, Zhejiang 200300, China
| | - Jinming Lu
- College of Forestry and Biotechnology, Zhejiang Agriculture & Forestry University, Lin'an, Zhejiang 200300, China
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13
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Abstract
'Candidatus Liberibacter asiaticus' (Las) is an unculturable α-proteobacterium associated with citrus huanglongbing (HLB), a devastating disease currently threatening the citrus industry worldwide. Here, we present the genome sequence of Las strain TaiYZ2 from an HLB-affected pomelo tree in Hat Yai district, Songkhla Province, Thailand. The TaiYZ2 genome is composed of 1,230,623 bp with G+C content of 36.4%. This is the first Las genome sequence from Thailand, which will enrich current Las genome resource and facilitate HLB research and management.
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Affiliation(s)
- Tao Li
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou, China
| | - Narit Thaochan
- Pest Management Biotechnology and Plant Physiology Laboratory, Faculty of Natural Resources, Prince of Songkla University, Hat Yai, Songkhla, Thailand
| | - Jiaquan Huang
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou, China
- San Joaquin Valley Agricultural Sciences Center, Agricultural Research Service, United States Department of Agriculture, Parlier, California, U.S.A
| | - Jianchi Chen
- San Joaquin Valley Agricultural Sciences Center, Agricultural Research Service, United States Department of Agriculture, Parlier, California, U.S.A
| | - Xiaoling Deng
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou, China
| | - Zheng Zheng
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou, China
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14
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Zhang M, Yang C, Powell CA, Avery PB, Wang J, Huang Y, Duan Y. Field Evaluation of Integrated Management for Mitigating Citrus Huanglongbing in Florida. Front Plant Sci 2019; 9:1890. [PMID: 30766544 PMCID: PMC6365889 DOI: 10.3389/fpls.2018.01890] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Accepted: 12/06/2018] [Indexed: 05/21/2023]
Abstract
Citrus huanglongbing (HLB) is extremely difficult to control because the psyllid-transmitted bacterial pathogen resides inside the citrus phloem and the disease is systemic. In Florida, the nine billion dollar citrus industry has been significantly impacted by severe HLB epidemics. To combat citrus HLB, in this study we implemented an integrated strategy that includes chemotherapy, thermotherapy, and additional nutrition treatment in three different field trials over three consecutive years. In these trials, only trees already showing HLB symptoms with Ct values ranging from 25.1 to 27.7 were selected for treatments. To assess the complex interactions, we used several methods for evaluating the effectiveness of integrated management, including the slopes (b) of the Ct increase (dy/dt), the pathogenic index (PI) and the decline index (DI) from Ct value and tree scores, and the therapeutic efficacies from PI and DI. This comprehensive analysis showed that most of the tested chemicals were effective to some degree in killing or suppressing the Las bacterium, with higher therapeutic efficacies seen for Grove B, where citrus trees were severely affected by HLB, and it had a higher number of psyllids, relative to Grove E and P in the first 2 years. Trunk-injected penicillin G potassium was the most effective chemical treatment in all groves, followed by Oxytetracycline Calcium Complex, and Silver Nitrate delivered as foliar sprays. Although the steam heat treatment and additional nutrition did not eliminate or suppress Las over the long term, these treatments did positively affect tree growth and recovery in the short term. Overall, our results provide new insights into HLB control method and strategy for integrated management for HLB epidemic plantations.
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Affiliation(s)
- Muqing Zhang
- Agricultural Science College, Guangxi University, Nanning, China
- Indian River Research and Education Center, University of Florida, Fort Pierce, FL, United States
- US Horticultural Research Laboratory, USDA-ARS, Fort Pierce, FL, United States
| | - Chuanyu Yang
- Agricultural Science College, Guangxi University, Nanning, China
- Indian River Research and Education Center, University of Florida, Fort Pierce, FL, United States
| | - Charles A. Powell
- Indian River Research and Education Center, University of Florida, Fort Pierce, FL, United States
| | - Pasco B. Avery
- Indian River Research and Education Center, University of Florida, Fort Pierce, FL, United States
| | - Jihua Wang
- Agricultural Science College, Guangxi University, Nanning, China
- Indian River Research and Education Center, University of Florida, Fort Pierce, FL, United States
| | - Youzong Huang
- Agricultural Science College, Guangxi University, Nanning, China
- Indian River Research and Education Center, University of Florida, Fort Pierce, FL, United States
| | - Yongping Duan
- US Horticultural Research Laboratory, USDA-ARS, Fort Pierce, FL, United States
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15
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Pitino M, Allen V, Duan Y. LasΔ5315 Effector Induces Extreme Starch Accumulation and Chlorosis as Ca. Liberibacter asiaticus Infection in Nicotiana benthamiana. Front Plant Sci 2018; 9:113. [PMID: 29467782 PMCID: PMC5808351 DOI: 10.3389/fpls.2018.00113] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Accepted: 01/22/2018] [Indexed: 05/21/2023]
Abstract
Huanglongbing (HLB), a destructive plant bacterial disease, severely impedes worldwide citrus production. HLB is associated with a phloem-limited α-proteobacterium, Candidatus Liberibacter asiaticus (Las). Las infection causes yellow shoots and blotchy mottle on leaves and is associated with excessive starch accumulation. However, the mechanisms underlying the starch accumulation remain unknown. We previously showed that the Las5315mp effector induced callose deposition and cell death in Nicotiana benthamiana. In this study, we demonstrated that Las can experimentally infect N. benthamiana via dodder transmission. Furthermore, we revealed another key function of the Las5315 effector by demonstrating that transient expression of the truncated form of the effector, LasΔ5315, induced excessive starch accumulation by 6 fold after 8 dpi in N. benthamiana after removal of the chloroplast transit peptide from the Las5315mp. The induction mechanisms of LasΔ5315 in N. benthamiana were attributed to the up-regulation of ADP-glucose pyrophosphorylase, granule-bound starch synthase, soluble starch synthase, and starch branching enzyme for increasing starch production, and to the significant down-regulation of the starch degradation enzymes: alpha-glucosidase, alpha-amylase, and glycosyl hydrolase for decreasing starch degradation. This is the first report that Las can infect the model plant N. benthamiana. Using this model plant, we demonstrated that the LasΔ5315 effector caused the most prominent HLB symptoms, starch accumulation and chlorosis as Las infection in N. benthamiana. Altogether the Las 5315 effector is critical for Las pathogenesis, and therefore, an important target for interference.
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Affiliation(s)
| | | | - Yongping Duan
- US Horticultural Research Laboratory, USDA-ARS, Fort Pierce, FL, United States
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16
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Zhang MQ, Guo Y, Powell CA, Doud MS, Yang CY, Zhou H, Duan YP. Zinc treatment increases the titre of 'Candidatus Liberibacter asiaticus' in huanglongbing-affected citrus plants while affecting the bacterial microbiomes. J Appl Microbiol 2016; 120:1616-28. [PMID: 26909469 DOI: 10.1111/jam.13102] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Revised: 01/28/2016] [Accepted: 02/05/2016] [Indexed: 12/26/2022]
Abstract
AIMS Huanglongbing (HLB)-affected citrus often display zinc deficiency symptoms. In this study, supplemental zinc was applied to citrus to determine its effect on Candidatus Liberibacter asiaticus (Las) titre, HLB symptoms, and leaf microbiome. METHODS AND RESULTS HLB-affected citrus were treated with various amounts of zinc. The treatments promoted Las growth and affected microbiomes in citrus leaves. Phylochip(™) -based results indicated that 5475 of over 50 000 known Operational Taxonomic Units (OTUs) in 52 phyla were detected in the midribs of HLB-affected citrus, of which Proteobacteria was the most abundant, followed by Firmicutes and Actinobacteria. In comparison, the microbiomes of zinc-treated diseased plants had overall more OTUs with higher amounts of Proteobacteria, but decreased percentages of Firmicutes and Actinobacteria. In addition, more OTUs of siderophore-producing bacteria were present. Only zinc-sensitive Staphylococcaceae had higher OTU's in the diseased plants without zinc treatments. CONCLUSIONS Although HLB-affected citrus appear zinc deficient, zinc amendments increased the pathogen levels and shifted the microbiome. SIGNIFICANCE AND IMPACT OF THE STUDY HLB is currently the most devastating disease of citrus worldwide. Zinc is often applied to HLB-affected citrus due to zinc deficiency symptoms. This study provided new insights into the potential effects of zinc on HLB and the microbial ecology of citrus.
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Affiliation(s)
- M Q Zhang
- State Key Lab for Conservation and Utilization of Subtropical Agro-biological Resources, Guangxi University, Nanning, China.,IRREC-IFAS, University of Florida, Fort Pierce, FL, USA.,USHRL, USDA-ARS, Fort Pierce, FL, USA
| | - Y Guo
- IRREC-IFAS, University of Florida, Fort Pierce, FL, USA
| | - C A Powell
- IRREC-IFAS, University of Florida, Fort Pierce, FL, USA
| | - M S Doud
- USHRL, USDA-ARS, Fort Pierce, FL, USA
| | - C Y Yang
- IRREC-IFAS, University of Florida, Fort Pierce, FL, USA
| | - H Zhou
- State Key Lab for Conservation and Utilization of Subtropical Agro-biological Resources, Guangxi University, Nanning, China
| | - Y P Duan
- USHRL, USDA-ARS, Fort Pierce, FL, USA
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