Dataset Information

?-caryophyllene emitted from a transgenic Arabidopsis or chemical dispenser repels Diaphorina citri, vector of Candidatus Liberibacters.

ABSTRACT: Production of citrus, the main fruit tree crop worldwide, is severely threatened by Huanglongbing (HLB), for which as yet a cure is not available. Spread of this bacterial disease in America and Asia is intimately connected with dispersal and feeding of the insect vector Diaphorina citri, oligophagous on rutaceous host plants. Effective control of this psyllid is an important component in successful HLB management programs. Volatiles released from the non-host guava have been shown to be repellent to the psyllid and to inhibit its response to citrus odour. By analysing VOC emission from guava we identified one volatile compound, (E)-?-caryophyllene, which at certain doses exerts a repellent effect on D. citri. Non-host plant rejection mediated by (E)-?-caryophyllene is demonstrated here by using Arabidopsis over-expression and knock-out lines. For the first time, results indicate that genetically engineered Arabidopsis plants with modified emission of VOCs can alter the behaviour of D. citri. This study shows that transgenic plants with an inherent ability to release (E)-?-caryophyllene can potentially be used in new protection strategies of citrus trees against HLB.

SUBMITTER: Alquezar B

PROVIDER: S-EPMC5514130 | biostudies-other | 2017 Jul

REPOSITORIES: biostudies-other

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β-caryophyllene emitted from a transgenic Arabidopsis or chemical dispenser repels Diaphorina citri, vector of Candidatus Liberibacters.

Alquézar Berta B Volpe Haroldo Xavier Linhares HXL Magnani Rodrigo Facchini RF de Miranda Marcelo Pedreira MP Santos Mateus Almeida MA Wulff Nelson Arno NA Bento Jose Mauricio Simões JMS Parra José Roberto Postali JRP Bouwmeester Harro H Peña Leandro L

Scientific reports 20170717 1

Production of citrus, the main fruit tree crop worldwide, is severely threatened by Huanglongbing (HLB), for which as yet a cure is not available. Spread of this bacterial disease in America and Asia is intimately connected with dispersal and feeding of the insect vector Diaphorina citri, oligophagous on rutaceous host plants. Effective control of this psyllid is an important component in successful HLB management programs. Volatiles released from the non-host guava have been shown to be repelle ...[more]

PMID: 28717202

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Project description:Insects are associated with diverse microbial communities that can have substantial effects on hosts. Here, we characterized the bacterial communities in the Asian citrus psyllid (ACP), Diaphorina citri (Hemiptera: Psyllidae), a major vector of the devastating pathogen "Candidatus Liberibacter asiaticus," which causes citrus Huanglongbing (HLB). In total, 256 ACP individuals across 15 field sites and one laboratory population in China were sequenced. The results showed that the bacterial community diversity was the highest in the Guilin population (average Shannon index, 1.27), and the highest value for richness was found in the Chenzhou population (average Chao1 index, 298). The bacterial community structures of the field-collected populations were significantly different, and all of them harbored Wolbachia, which was assigned to strain ST-173. Structural equation models revealed that the dominant Wolbachia strain had a significantly negative correlation with the annual mean temperature. In addition, the results obtained with populations infected with "Ca. Liberibacter asiaticus" indicated that in total, 140 bacteria could be involved in interactions with this bacterium. The ACP field populations harbored a more diverse bacterial community than the laboratory population, and the relative occurrences of some symbionts differed significantly. However, the bacterial community of the ACP laboratory colony was connected in a more complex network structure (average degree, 54.83) than that of the field populations (average degree, 10.62). Our results provide evidence that environmental factors can influence the bacterial community structure and bacterial relative abundance in ACP populations. This is likely due to the adaptation of ACPs to local environments. IMPORTANCE The Asian citrus psyllid (ACP) is an important vector of the HLB pathogen, which is a major threat to citrus production around the world. Bacterial communities harbored by insects could be affected by different environmental factors. Understanding these factors that affect the bacterial community of the ACP could be important for the better management of HLB transmission. This work surveyed ACP field populations in mainland China in order to explore the bacterial community diversity of different populations and the potential relationships between environmental factors and predominant symbionts. We have assessed the differences in ACP bacterial communities and identified the prevalent Wolbachia strains in the field. In addition, we compared the bacterial communities of ACP field-collected and laboratory populations. Comparing populations subjected to contrasting conditions could help us to better understand how the ACP adapts to local environmental conditions. Our study provides new insights into how environmental factors influence the bacterial community of the ACP.

Project description:Citrus Huanglongbing (HLB) associated with 'Candidatus Liberibacter asiaticus' (Las) and citrus canker disease incited by Xanthomonas citri are the most devastating citrus diseases worldwide. To control citrus HLB and canker disease, we previously screened over forty antimicrobial peptides (AMPs) in vitro for their potential application in genetic engineering. D2A21 was one of the most active AMPs against X. citri, Agrobacterium tumefaciens and Sinorhizobium meliloti with low hemolysis activity. Therefore, we conducted this work to assess transgenic expression of D2A21 peptide to achieve citrus resistant to canker and HLB. We generated a construct expressing D2A21 and initially transformed tobacco as a model plant. Transgenic tobacco expressing D2A21 was obtained by Agrobacterium-mediated transformation. Successful transformation and D2A21 expression was confirmed by molecular analysis. We evaluated disease development incited by Pseudomonas syringae pv. tabaci in transgenic tobacco. Transgenic tobacco plants expressing D2A21 showed remarkable disease resistance compared to control plants. Therefore, we performed citrus transformations with the same construct and obtained transgenic Carrizo citrange. Gene integration and gene expression in transgenic plants were determined by PCR and RT-qPCR. Transgenic Carrizo expressing D2A21 showed significant canker resistance while the control plants showed clear canker symptoms following both leaf infiltration and spray inoculation with X. citri 3213. Transgenic Carrizo plants were challenged for HLB evaluation by grafting with Las infected rough lemon buds. Las titer was determined by qPCR in the leaves and roots of transgenic and control plants. However, our results showed that transgenic plants expressing D2A21 did not significantly reduce Las titer compared to control plants. We demonstrated that transgenic expression of D2A21 conferred resistance to diseases incited by P. syringae pv. tabaci and X. citri but not Las. Our results underscore the difficulty in controlling HLB compared to other bacterial diseases.

Project description:Huanglongbing (HLB) is a citrus disease of worldwide importance, associated with the presence of Candidatus Liberibacter asiaticus (Las) and vectored by the psyllid Diaphorina citri in Asia and the Americas. To properly manage HLB, removal of inoculum sources and control of the psyllid are undertaken. We evaluated the percentage of the psyllid population with Las, sampled from yellow sticky traps over a three-year period and its relationship with insect population, regions, season of the year, and HLB management in citrus areas in the southwestern, central, and northern regions of São Paulo (SP) and southwestern region of Minas Gerais states, Brazil. In each reading, up to 50 psyllids per region were collected and detection of Las in individual psyllids were made by quantitative polymerase chain reaction. The percentage of psyllids with Las-an average of 65.3%-was constant throughout the year in the southwestern region of SP state, while showing an increase from spring to autumn when sampled from central to northern regions. The proportion of psyllids carrying Las from each region and year period were compared by a proportion test and spectral density analysis. The proportion of psyllids carrying Las evaluated in the same region in different seasons presented statistical differences in central (Araraquara) and southwestern (Santa Cruz do Rio Pardo) regions in 2015, with higher values in the first semester (summer and autumn) than in the second semester (winter and spring). Orchards with poor HLB management had higher incidence of psyllids with Las. Spectral density analysis indicated that good management areas had 50% less relevant peaks of psyllids with Las than in areas with poor HLB management practices. The relationship between the percentage of psyllids carrying Las and the number of captured psyllids in the region in a given time denotes the most critical intake time for HLB spread in citrus orchards. The reduction in the population of psyllids carrying Las is a direct benefit from the use of good management practices.

Dataset Information

?-caryophyllene emitted from a transgenic Arabidopsis or chemical dispenser repels Diaphorina citri, vector of Candidatus Liberibacters.

Publications

β-caryophyllene emitted from a transgenic Arabidopsis or chemical dispenser repels Diaphorina citri, vector of Candidatus Liberibacters.

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