1
|
Huang X, Su L, Xian B, Yu Q, Zhang M, Fan J, Zhang C, Liu Y, He H, Zhong X, Li M, Chen S, He Y, Li Q. Genome-wide identification and characterization of the sweet orange (Citrus sinensis) basic helix-loop-helix (bHLH) family reveals a role for CsbHLH085 as a regulator of citrus bacterial canker resistance. Int J Biol Macromol 2024; 267:131442. [PMID: 38621573 DOI: 10.1016/j.ijbiomac.2024.131442] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Revised: 03/29/2024] [Accepted: 04/05/2024] [Indexed: 04/17/2024]
Abstract
Citrus bacterial canker (CBC) is a harmful bacterial disease caused by Xanthomonas citri subsp. citri (Xcc), negatively impacting citrus production worldwide. The basic helix-loop-helix (bHLH) transcription factor family plays crucial roles in plant development and stress responses. This study aimed to identify and annotate bHLH proteins encoded in the Citrus sinensis genome and explore their involvement and functional importance in regulating CBC resistance. A total of 135 putative CsbHLHs TFs were identified and categorized into 16 subfamilies. Their chromosomal locations, collinearity, and phylogenetic relationships were comprehensively analyzed. Upon Xcc strain YN1 infection, certain CsbHLHs were differentially regulated in CBC-resistant and CBC-sensitive citrus varieties. Among these, CsbHLH085 was selected for further functional characterization. CsbHLH085 was upregulated in the CBC-resistant citrus variety, was localized in the nucleus, and had a transcriptional activation activity. CsbHLH085 overexpression in Citrus significantly enhanced CBC resistance, accompanied by increased levels of salicylic acid (SA), jasmonic acid (JA), reactive oxygen species (ROS), and decreased levels of abscisic acid (ABA) and antioxidant enzymes. Conversely, CsbHLH085 virus-induced gene silencing resulted in opposite phenotypic and biochemical responses. CsbHLH085 silencing also affected the expression of phytohormone biosynthesis and signaling genes involved in SA, JA, and ABA signaling. These findings highlight the crucial role of CsbHLH085 in regulating CBC resistance, suggesting its potential as a target for biotechnological-assisted breeding citrus varieties with improved resistance against phytopathogens.
Collapse
Affiliation(s)
- Xin Huang
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Southwest University, Chongqing 400712, China
| | - Liyan Su
- School of Biological and Environmental Engineering, Xi'an University, Xi'an 710065, China
| | - Baohang Xian
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Southwest University, Chongqing 400712, China
| | - Qiyuan Yu
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Southwest University, Chongqing 400712, China
| | - Miao Zhang
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Southwest University, Chongqing 400712, China
| | - Jie Fan
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Southwest University, Chongqing 400712, China
| | - Chenxi Zhang
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Southwest University, Chongqing 400712, China
| | - Yiqi Liu
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Southwest University, Chongqing 400712, China
| | - Houzheng He
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Southwest University, Chongqing 400712, China
| | - Xin Zhong
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Southwest University, Chongqing 400712, China
| | - Man Li
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Southwest University, Chongqing 400712, China
| | - Shanchun Chen
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Southwest University, Chongqing 400712, China; National Citrus Engineering Research Center, Chongqing 400712, China
| | - Yongrui He
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Southwest University, Chongqing 400712, China; National Citrus Engineering Research Center, Chongqing 400712, China.
| | - Qiang Li
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Southwest University, Chongqing 400712, China; National Citrus Engineering Research Center, Chongqing 400712, China.
| |
Collapse
|
2
|
Li R, Wang X, Hu Y, Huang G. Analysis of huanglongbing-associated RNA-seq data reveals disturbances in biological processes within Citrus spp. triggered by Candidatus Liberibacter asiaticus infection. FRONTIERS IN PLANT SCIENCE 2024; 15:1388163. [PMID: 38660443 PMCID: PMC11039969 DOI: 10.3389/fpls.2024.1388163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/19/2024] [Accepted: 03/27/2024] [Indexed: 04/26/2024]
Abstract
Introduction Huanglongbing (HLB), a disease that's ubiquitous worldwide, wreaks havoc on the citrus industry. The primary culprit of HLB is the gram-negative bacterium Candidatus Liberibacter asiaticus (CLas) that infects the phloem, but its damaging mechanism is yet to be fully understood. Methods and results In this study, a multitude of tools including weighted correlation network analysis (WGCNA), protein-protein interaction (PPI) network analysis and gene expression profiling are employed to unravel the intricacies of its pathogenesis. The investigation pinpoints various central genes, such as the ethylene-responsive transcription factor 9 (ERF9) and thioredoxin reductase 1 (TrxR1), that are associated with CLas invasion and resultant disturbances in numerous biological operations. Additionally, the study uncovers a range of responses through the detection of differential expressed genes (DEGs) across different experiments. The discovery of core DEGs leads to the identification of pivotal genes such as the sieve element occlusion (SEO) and the wall-associated receptor kinase-like 15 (WAKL15). PPI network analysis highlights potential vital proteins, while GO and KEGG pathway enrichment analysis illustrate a significant impact on multiple defensive and metabolic pathways. Gene set enrichment analysis (GSEA) indicates significant alterations in biological processes such as leaf senescence and response to biotic stimuli. Discussion This all-encompassing approach extends valuable understanding into the pathogenesis of CLas, potentially aiding future research and therapeutic strategies for HLB.
Collapse
Affiliation(s)
- Ruimin Li
- College of Life Sciences, Gannan Normal University, Ganzhou, China
- China-USA Citrus Huanglongbing Joint Laboratory, National Navel Orange Engineering Research Center, Gannan Normal University, Ganzhou, China
| | - Xinyou Wang
- College of Life Sciences, Gannan Normal University, Ganzhou, China
| | - Yanan Hu
- College of Life Sciences, Gannan Normal University, Ganzhou, China
| | - Guiyan Huang
- College of Life Sciences, Gannan Normal University, Ganzhou, China
- China-USA Citrus Huanglongbing Joint Laboratory, National Navel Orange Engineering Research Center, Gannan Normal University, Ganzhou, China
| |
Collapse
|
3
|
Fan J, Xian B, Huang X, Yu Q, Zhang M, Zhang C, Jia R, Chen S, He Y, Li Q. Genome-Wide Identification and Characterization of the Sweet Orange ( Citrus sinensis) GATA Family Reveals a Role for CsGATA12 as a Regulator of Citrus Bacterial Canker Resistance. Int J Mol Sci 2024; 25:2924. [PMID: 38474170 DOI: 10.3390/ijms25052924] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2023] [Revised: 02/06/2024] [Accepted: 02/27/2024] [Indexed: 03/14/2024] Open
Abstract
Citrus bacterial canker (CBC) is a severe bacterial infection caused by Xanthomonas citri subsp. citri (Xcc), which continues to adversely impact citrus production worldwide. Members of the GATA family are important regulators of plant development and regulate plant responses to particular stressors. This report aimed to systematically elucidate the Citrus sinensis genome to identify and annotate genes that encode GATAs and evaluate the functional importance of these CsGATAs as regulators of CBC resistance. In total, 24 CsGATAs were identified and classified into four subfamilies. Furthermore, the phylogenetic relationships, chromosomal locations, collinear relationships, gene structures, and conserved domains for each of these GATA family members were also evaluated. It was observed that Xcc infection induced some CsGATAs, among which CsGATA12 was chosen for further functional validation. CsGATA12 was found to be localized in the nucleus and was differentially upregulated in the CBC-resistant and CBC-sensitive Kumquat and Wanjincheng citrus varieties. When transiently overexpressed, CsGATA12 significantly reduced CBC resistance with a corresponding increase in abscisic acid, jasmonic acid, and antioxidant enzyme levels. These alterations were consistent with lower levels of salicylic acid, ethylene, and reactive oxygen species. Moreover, the bacteria-induced CsGATA12 gene silencing yielded the opposite phenotypic outcomes. This investigation highlights the important role of CsGATA12 in regulating CBC resistance, underscoring its potential utility as a target for breeding citrus varieties with superior phytopathogen resistance.
Collapse
Affiliation(s)
- Jie Fan
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Citrus Research Institute, Southwest University, Chongqing 400712, China
| | - Baohang Xian
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Citrus Research Institute, Southwest University, Chongqing 400712, China
| | - Xin Huang
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Citrus Research Institute, Southwest University, Chongqing 400712, China
| | - Qiyuan Yu
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Citrus Research Institute, Southwest University, Chongqing 400712, China
| | - Miao Zhang
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Citrus Research Institute, Southwest University, Chongqing 400712, China
| | - Chenxi Zhang
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Citrus Research Institute, Southwest University, Chongqing 400712, China
| | - Ruirui Jia
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Citrus Research Institute, Southwest University, Chongqing 400712, China
- National Citrus Engineering Research Center, Chongqing 400712, China
| | - Shanchun Chen
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Citrus Research Institute, Southwest University, Chongqing 400712, China
- National Citrus Engineering Research Center, Chongqing 400712, China
| | - Yongrui He
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Citrus Research Institute, Southwest University, Chongqing 400712, China
- National Citrus Engineering Research Center, Chongqing 400712, China
| | - Qiang Li
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Citrus Research Institute, Southwest University, Chongqing 400712, China
- National Citrus Engineering Research Center, Chongqing 400712, China
| |
Collapse
|
4
|
Sarkar P, Lin CY, Buritica JR, Killiny N, Levy A. Crossing the Gateless Barriers: Factors Involved in the Movement of Circulative Bacteria Within Their Insect Vectors. PHYTOPATHOLOGY 2023; 113:1805-1816. [PMID: 37160668 DOI: 10.1094/phyto-07-22-0249-ia] [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: 05/11/2023]
Abstract
Plant bacterial pathogens transmitted by hemipteran vectors pose a large threat to the agricultural industry worldwide. Although virus-vector relationships have been widely investigated, a significant gap exists in our understanding of the molecular interactions between circulative bacteria and their insect vectors, mainly leafhoppers and psyllids. In this review, we will describe how these bacterial pathogens adhere, invade, and proliferate inside their insect vectors. We will also highlight the different transmission routes and molecular factors of phloem-limited bacteria that maintain an effective relationship with the insect host. Understanding the pathogen-vector relationship at the molecular level will help in the management of vector-borne bacterial diseases.
Collapse
Affiliation(s)
- Poulami Sarkar
- Citrus Research and Education Center, University of Florida, Lake Alfred, FL 33850
| | - Chun-Yi Lin
- Citrus Research and Education Center, University of Florida, Lake Alfred, FL 33850
| | - Jacobo Robledo Buritica
- Citrus Research and Education Center, University of Florida, Lake Alfred, FL 33850
- Department of Plant Pathology, University of Florida, Gainesville, FL 32611
| | - Nabil Killiny
- Citrus Research and Education Center, University of Florida, Lake Alfred, FL 33850
- Department of Plant Pathology, University of Florida, Gainesville, FL 32611
| | - Amit Levy
- Citrus Research and Education Center, University of Florida, Lake Alfred, FL 33850
- Department of Plant Pathology, University of Florida, Gainesville, FL 32611
| |
Collapse
|
5
|
Zhang S, Wang X, He J, Zhang S, Zhao T, Fu S, Zhou C. A Sec-dependent effector, CLIBASIA_04425, contributes to virulence in ' Candidatus Liberibater asiaticus'. FRONTIERS IN PLANT SCIENCE 2023; 14:1224736. [PMID: 37554557 PMCID: PMC10405523 DOI: 10.3389/fpls.2023.1224736] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/18/2023] [Accepted: 07/05/2023] [Indexed: 08/10/2023]
Abstract
Citrus Huanglongbing (HLB) is the most destructive citrus disease worldwide, mainly caused by 'Candidatus Liberibacter asiaticus' (CLas). It encodes a large number of Sec-dependent effectors that contribute to HLB progression. In this study, an elicitor triggering ROS burst and cell death in Nicotiana benthamiana, CLIBASIA_04425 (CLas4425), was identified. Of particular interest, its cell death-inducing activity is associated with its subcellular localization and the cytoplasmic receptor Botrytis-induced kinase 1 (BIK1). Compared with CLas infected psyllids, CLas4425 showed higher expression level in planta. The transient expression of CLas4425 in N. benthamiana and its overexpression in Citrus sinensis enhanced plant susceptibility to Pseudomonas syringae pv. tomato DC3000 ΔhopQ1-1 and CLas, respectively. Furthermore, the salicylic acid (SA) level along with the expression of genes NPR1/EDS1/NDR1/PRs in SA signal transduction was repressed in CLas4425 transgenic citrus plants. Taken together, CLas4425 is a virulence factor that promotes CLas proliferation, likely by interfering with SA-mediated plant immunity. The results obtained facilitate our understanding of CLas pathogenesis.
Collapse
Affiliation(s)
- Shushe Zhang
- Citrus Research Institute, Southwest University/National Citrus Engineering Research Center, Chongqing, China
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Chinese Academy of Agriculture Sciences, Institute of Plant Protection, Beijing, China
| | - Xuefeng Wang
- Citrus Research Institute, Southwest University/National Citrus Engineering Research Center, Chongqing, China
| | - Jun He
- Citrus Research Institute, Southwest University/National Citrus Engineering Research Center, Chongqing, China
| | - Song Zhang
- Guangxi Citrus Breeding and Cultivation Engineering Technology Center Academy of Specialty Crops, Guangxi, Guilin, China
| | - Tingchang Zhao
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Chinese Academy of Agriculture Sciences, Institute of Plant Protection, Beijing, China
| | - Shimin Fu
- Citrus Research Institute, Southwest University/National Citrus Engineering Research Center, Chongqing, China
| | - Changyong Zhou
- Citrus Research Institute, Southwest University/National Citrus Engineering Research Center, Chongqing, China
| |
Collapse
|
6
|
Wang S, Du M, Dong L, Qu R, Ran D, Ma J, Wang X, Xu L, Li W, He Y, Zou X. Function and molecular mechanism analysis of CaLasSDE460 effector involved in the pathogenesis of "Candidatus Liberibacter asiaticus" in citrus. MOLECULAR HORTICULTURE 2023; 3:14. [PMID: 37789492 PMCID: PMC10514941 DOI: 10.1186/s43897-023-00062-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Accepted: 07/10/2023] [Indexed: 10/05/2023]
Abstract
Citrus Huanglongbing (HLB), caused by Candidatus Liberibacter asiaticus (CaLas), is the most serious disease worldwide. CaLasSDE460 was previously characterized as a potential virulence factor of CaLas. However, the function and mechanism of CaLasSDE460 involved in CaLas against citrus is still elusive. Here, we showed that transgenic expression of CaLasSDE460 in Wanjincheng oranges (C. sinensis Osbeck) contributed to the early growth of CaLas and the development of symptoms. When the temperature increased from 25 °C to 32 °C, CaLas growth and symptom development in transgenic plants were slower than those in WT controls. RNA-seq analysis of transgenic plants showed that CaLasSDE460 affected multiple biological processes. At 25 °C, transcription activities of the "Protein processing in endoplasmic reticulum" and "Cyanoamino acid metabolism" pathways increased while transcription activities of many pathways decreased at 32 °C. 124 and 53 genes, separately annotated to plant-pathogen interaction and MAPK signaling pathways, showed decreased expression at 32 °C, compared with these (38 for plant-pathogen interaction and 17 for MAPK signaling) at 25 °C. Several important genes (MAPKKK14, HSP70b, NCED3 and WRKY33), remarkably affected by CaLasSDE460, were identified. Totally, our data suggested that CaLasSDE460 participated in the pathogenesis of CaLas through interfering transcription activities of citrus defense response and this interfering was temperature-dependent.
Collapse
Affiliation(s)
- Shuai Wang
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Citrus Research Institute, Southwest University/National Citrus Engineering Research Center, Chongqing, People's Republic of China
| | - Meixia Du
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Citrus Research Institute, Southwest University/National Citrus Engineering Research Center, Chongqing, People's Republic of China
| | - Liting Dong
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Citrus Research Institute, Southwest University/National Citrus Engineering Research Center, Chongqing, People's Republic of China
| | - Rongrong Qu
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Citrus Research Institute, Southwest University/National Citrus Engineering Research Center, Chongqing, People's Republic of China
| | - Danlu Ran
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Citrus Research Institute, Southwest University/National Citrus Engineering Research Center, Chongqing, People's Republic of China
| | - Juanjuan Ma
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Citrus Research Institute, Southwest University/National Citrus Engineering Research Center, Chongqing, People's Republic of China
| | - Xuefeng Wang
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Citrus Research Institute, Southwest University/National Citrus Engineering Research Center, Chongqing, People's Republic of China
| | - Lanzhen Xu
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Citrus Research Institute, Southwest University/National Citrus Engineering Research Center, Chongqing, People's Republic of China
| | - Weimin Li
- Key Laboratory for Northern Urban, Agriculture of Ministry of Agriculture and Rural Affairs, Beijing University of Agriculture, Beijing, People's Republic of China
| | - Yongrui He
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Citrus Research Institute, Southwest University/National Citrus Engineering Research Center, Chongqing, People's Republic of China
| | - Xiuping Zou
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Citrus Research Institute, Southwest University/National Citrus Engineering Research Center, Chongqing, People's Republic of China.
- Key Laboratory for Northern Urban, Agriculture of Ministry of Agriculture and Rural Affairs, Beijing University of Agriculture, Beijing, People's Republic of China.
| |
Collapse
|
7
|
Zheng Y, Zhang J, Li Y, Liu Y, Liang J, Wang C, Fang F, Deng X, Zheng Z. Pathogenicity and Transcriptomic Analyses of Two " Candidatus Liberibacter asiaticus" Strains Harboring Different Types of Phages. Microbiol Spectr 2023; 11:e0075423. [PMID: 37071011 PMCID: PMC10269750 DOI: 10.1128/spectrum.00754-23] [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: 02/17/2023] [Accepted: 03/31/2023] [Indexed: 04/19/2023] Open
Abstract
"Candidatus Liberibacter asiaticus" is one of the putative causal agents of citrus Huanglongbing (HLB), a highly destructive disease threatening the global citrus industry. Several types of phages had been identified in "Ca. Liberibacter asiaticus" strains and found to affect the biology of "Ca. Liberibacter asiaticus." However, little is known about the influence of phages in "Ca. Liberibacter asiaticus" pathogenicity. In this study, two "Ca. Liberibacter asiaticus" strains, PYN and PGD, harboring different types of phages were collected and used for pathogenicity analysis in periwinkle (Catharanthus roseus). Strain PYN carries a type 1 phage (P-YN-1), and PGD harbors a type 2 phage (P-GD-2). Compared to strain PYN, strain PGD exhibited a faster reproduction rate and higher virulence in periwinkle: leaf symptoms appeared earlier, and there was a stronger inhibition in the growth of new flush. Estimation of phage copy numbers by type-specific PCR indicated that there are multiple copies of phage P-YN-1 in strain PYN, while strain PGD carries only a single copy of phage P-GD-2. Genome-wide gene expression profiling revealed the lytic activity of P-YN-1 phage, as evidenced by the unique expression of genes involved in lytic cycle, which may limit the propagation of strain PYN and lead to a delayed infection in periwinkle. However, the activation of genes involved in lysogenic conversion of phage P-GD-1 indicated it could reside within the "Ca. Liberibacter asiaticus" genome as a prophage form in strain PGD. Comparative transcriptome analysis showed that the significant differences in expression of virulence factor genes, including genes associated with pathogenic effectors, transcriptional factors, the Znu transport system, and the heme biosynthesis pathway, could be another major determinant of virulence variation between two "Ca. Liberibacter asiaticus" strains. This study expanded our knowledge of "Ca. Liberibacter asiaticus" pathogenicity and provided new insights into the differences in pathogenicity between "Ca. Liberibacter asiaticus" strains. IMPORTANCE Citrus Huanglongbing (HLB), also called citrus greening disease, is a highly destructive disease threatening citrus production worldwide. "Candidatus Liberibacter asiaticus" is one of the most common putative causal agents of HLB. Phages of "Ca. Liberibacter asiaticus" have recently been identified and found to affect "Ca. Liberibacter asiaticus" biology. Here, we found that "Ca. Liberibacter asiaticus" strains harboring different types of phages (type 1 or type 2) showed different levels of pathogenicity and multiplication patterns in the periwinkle plant (Catharanthus roseus). Transcriptome analysis revealed the possible lytic activity of type 1 phage in a "Ca. Liberibacter asiaticus" strain, which could limit the propagation of "Ca. Liberibacter asiaticus" and lead to the delayed infection in periwinkle. The heterogeneity in the transcriptome profiles, particularly the significant differences in expression of virulence factors genes, could be another major determinant of difference in virulence observed between the two "Ca. Liberibacter asiaticus" strains. These findings improved our understanding of "Ca. Liberibacter asiaticus"-phage interaction and provided insight into "Ca. Liberibacter asiaticus" pathogenicity.
Collapse
Affiliation(s)
- Yongqin Zheng
- National Key Laboratory of Green Pesticide, South China Agricultural University, Guangzhou, Guangdong, China
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou, Guangdong, China
| | - Jingxue Zhang
- National Key Laboratory of Green Pesticide, South China Agricultural University, Guangzhou, Guangdong, China
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou, Guangdong, China
| | - Yun Li
- National Key Laboratory of Green Pesticide, South China Agricultural University, Guangzhou, Guangdong, China
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou, Guangdong, China
| | - Yaoxin Liu
- Horticulture Research Institute, Guangxi Academy of Agricultural Sciences, Nanning, Guangxi, China
| | - Jiayin Liang
- National Key Laboratory of Green Pesticide, South China Agricultural University, Guangzhou, Guangdong, China
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou, Guangdong, China
| | - Cheng Wang
- National Key Laboratory of Green Pesticide, South China Agricultural University, Guangzhou, Guangdong, China
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou, Guangdong, China
| | - Fang Fang
- National Key Laboratory of Green Pesticide, South China Agricultural University, Guangzhou, Guangdong, China
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou, Guangdong, China
| | - Xiaoling Deng
- National Key Laboratory of Green Pesticide, South China Agricultural University, Guangzhou, Guangdong, China
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou, Guangdong, China
| | - Zheng Zheng
- National Key Laboratory of Green Pesticide, South China Agricultural University, Guangzhou, Guangdong, China
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou, Guangdong, China
| |
Collapse
|
8
|
Shen P, Li X, Fu S, Zhou C, Wang X. A " Candidatus Liberibacter asiaticus"-secreted polypeptide suppresses plant immune responses in Nicotiana benthamiana and Citrus sinensis. FRONTIERS IN PLANT SCIENCE 2022; 13:997825. [PMID: 36352861 PMCID: PMC9638108 DOI: 10.3389/fpls.2022.997825] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Accepted: 08/23/2022] [Indexed: 05/22/2023]
Abstract
Citrus Huanglongbing (HLB), known as the most economically devastating disease in citrus industry, is mainly caused by phloem-restricted Gram-negative bacterium "Candidatus Liberibacter asiaticus" (CLas). To date, CLas is still unculturable in vitro, which has been dramatically delaying the research on its pathogenesis, and only few Sec-dependent effectors (SDEs) have been identified to elucidate the pathogenesis of CLas. Here, we confirmed that a CLas-secreted Sec-dependent polypeptide, namely SECP8 (CLIBASIA_05330), localized in nucleus, cytoplasm and cytoplasmic membrane, and showed remarkably higher transcript abundance in citrus than in psyllids. Potato virus X (PVX)-mediated transient expression assays indicated that mSECP8 (the mature form of SECP8) suppressed pro-apoptotic mouse protein BAX and Phytophthora infestans elicitin INF1-triggered hypersensitive response (HR) associated phenotypes, including cell death, H2O2 accumulation and callose deposition. Intriguingly, mSECP8 also inhibited SDE1 (CLIBASIA_05315)-induced water-soaked and dwarfing symptoms in Nicotiana benthamiana. In addition, mSECP8 can promote the susceptibility of transgenic Wanjincheng orange (Citrus sinensis) to CLas invasion and further HLB symptom development, and it contributes to the proliferation of Xanthomonas citri subsp. citri (Xcc). Moreover, the expression of ten immunity-related genes were significantly down-regulated in mSECP8 transgenic citrus than those in wide-type (WT) plants. Overall, we propose that mSECP8 may serve as a novel broad-spectrum suppressor of plant immunity, and provide the first evidence counteractive effect among CLas effectors. This study will enrich and provide new evidences for elucidating the pathogenic mechanisms of CLas in citrus host.
Collapse
Affiliation(s)
| | | | | | - Changyong Zhou
- National Citrus Engineering Research Center, Citrus Research Institute, Southwest University, Chongqing, China
| | - Xuefeng Wang
- National Citrus Engineering Research Center, Citrus Research Institute, Southwest University, Chongqing, China
| |
Collapse
|