Changes in carbohydrate metabolism in <i>Citrus sinensis</i> infected with ‘<i>Candidatus</i> Liberibacter asiaticus’

Fan, Jing; Chen, C.; Brlansky, R. H.; Gmitter, Frederick G.; Li, Z.-G.

doi:10.1111/j.1365-3059.2010.02328.x

Cited by 125 publications

(119 citation statements)

References 30 publications

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“…However, further analysis of sugar concentrations will be necessary to clarify the causes and effects of disease symptoms in the fruit. Other studies on CaLas-infected leaves have shown increased sucrose and glucose, but not fructose [37]. In fruit, it is possible that altered fructose and glucose concentrations might be responsible for physiological disorders and affect source-sink relationships with leaves.…”

Section: Discussionmentioning

confidence: 91%

Transcriptome Profiling of Citrus Fruit Response to Huanglongbing Disease

et al. 2012

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Huanglongbing (HLB) or “citrus greening” is the most destructive citrus disease worldwide. In this work, we studied host responses of citrus to infection with Candidatus Liberibacter asiaticus (CaLas) using next-generation sequencing technologies. A deep mRNA profile was obtained from peel of healthy and HLB-affected fruit. It was followed by pathway and protein-protein network analysis and quantitative real time PCR analysis of highly regulated genes. We identified differentially regulated pathways and constructed networks that provide a deep insight into the metabolism of affected fruit. Data mining revealed that HLB enhanced transcription of genes involved in the light reactions of photosynthesis and in ATP synthesis. Activation of protein degradation and misfolding processes were observed at the transcriptomic level. Transcripts for heat shock proteins were down-regulated at all disease stages, resulting in further protein misfolding. HLB strongly affected pathways involved in source-sink communication, including sucrose and starch metabolism and hormone synthesis and signaling. Transcription of several genes involved in the synthesis and signal transduction of cytokinins and gibberellins was repressed while that of genes involved in ethylene pathways was induced. CaLas infection triggered a response via both the salicylic acid and jasmonic acid pathways and increased the transcript abundance of several members of the WRKY family of transcription factors. Findings focused on the fruit provide valuable insight to understanding the mechanisms of the HLB-induced fruit disorder and eventually developing methods based on small molecule applications to mitigate its devastating effects on fruit production.

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Section: Discussionmentioning

confidence: 91%

Transcriptome Profiling of Citrus Fruit Response to Huanglongbing Disease

et al. 2012

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“…One of the major physiological disorders of citrus caused by HLB disease has been reported to be the massive starch accumulation in leaf and stem tissues due to aberrant carbohydrate metabolism and phloem blockage (57,58). The tissues surrounding the fruit abscission zone are rich in vascular tissue where starch accumulation was found in HLB-affected citrus.…”

Section: Discussionmentioning

confidence: 92%

High Incidence of Preharvest Colonization of Huanglongbing-Symptomatic Citrus sinensis Fruit by Lasiodiplodia theobromae (Diplodia natalensis) and Exacerbation of Postharvest Fruit Decay by That Fungus

Zhao

Bai

McCollum

et al. 2015

Appl Environ Microbiol

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Huanglongbing (HLB), presumably caused by the bacterium "Candidatus Liberibacter asiaticus," is a devastating citrus disease associated with excessive preharvest fruit drop. Lasiodiplodia theobromae (diplodia) is the causal organism of citrus stem end rot (SER). The pathogen infects citrus fruit under the calyx abscission zone (AZ-C) and is associated with cell wall hydrolytic enzymes similar to plant enzymes involved in abscission. By means of DNA sequencing, diplodia was found in "Ca. Liberibacter asiaticus"-positive juice from HLB-symptomatic fruit (S) but not in "Ca. Liberibacter asiaticus"-negative juice. Therefore, the incidence of diplodia in fruit tissues, the impact on HLB-related postharvest decay, and the implications for HLB-related preharvest fruit drop were investigated in Hamlin and Valencia oranges. Quantitative PCR results (qPCR) revealed a significantly (P < 0.001) greater incidence of diplodia in the AZ-C of HLB-symptomatic (S; "Ca. Liberibacter asiaticus" threshold cycle [C T ] of <30) than in the AZ-C of in asymptomatic (AS; "Ca. Liberibacter asiaticus" C T of >30) fruit. In agreement with the qPCR results, 2 weeks after exposure to ethylene, the incidences of SER in S fruit were 66.7% (Hamlin) and 58.7% (Valencia), whereas for AS fruit the decay rates were 6.7% (Hamlin) and 5.3% (Valencia). Diplodia colonization of S fruit AZ-C was observed by scanning electron microscopy and confirmed by PCR test and morphology of conidia in isolates from the AZ-C after surface sterilization. Diplodia C T values were negatively correlated with ethylene production (R ‫؍‬ ؊0.838 for Hamlin; R ‫؍‬ ؊0.858 for Valencia) in S fruit, and positively correlated with fruit detachment force (R ‫؍‬ 0.855 for Hamlin; R ‫؍‬ 0.850 for Valencia), suggesting that diplodia colonization in AZ-C may exacerbate HLB-associated preharvest fruit drop. C itrus huanglongbing (HLB; also known as citrus greening) is one of the most devastating diseases of citrus and has spread throughout the major citrus-producing regions in Asia, Africa, and the Americas, causing great losses for the citrus industry worldwide (1). HLB is associated with "Candidatus Liberibacter" spp., which are Gram-negative, phloem-limited bacteria (2, 3). The Asian form of HLB is currently present in the United States, and the causal pathogen, bacterium "Candidatus Liberibacter asiaticus," was first confirmed in Southeast Florida in 2005 (1) and now is prevalent in all Florida citrus-growing areas in the state. HLB disease causes substantial economic loss by debilitating the productive capacity and shortening the life span of infected trees, promoting fruit drop and reducing fruit quality (4). Yield reduction can reach 30 to 100%, depending on the proportion of the canopy affected and the age of the trees during inoculation (1, 5).HLB-diseased citrus plants develop a multitude of symptoms. Leaf symptoms include chlorosis, which commonly appears in an asymmetric pattern referred to as "blotchy mottle" (4). Chlorosis may typically appear on a single branch and subse...

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“…Altered expression of these genes can cause abnormal circadian rhythms which, in turn, result in disorders of clock-regulated pathways, such as photosynthesis, transport of sugars, and starch metabolism (Harmer et al 2000). Interestingly, repression of photosynthesis pathway genes and disorders of carbohydrate metabolism (genes and metabolites) have been observed in HLB-affected sweet orange (Albrecht and Bowman 2008;Fan et al 2010Fan et al , 2011. It is suggested that the transcriptional changes of these MYB-related transcription factors may correlate to the interference of photosynthesis and carbohydrate metabolism in 'Ca.…”

Section: Significantly Hlb-modulated Pathways At Each Time Pointmentioning

confidence: 98%

Comparative Transcriptional and Anatomical Analyses of Tolerant Rough Lemon and Susceptible Sweet Orange in Response to ‘Candidatus Liberibacter asiaticus’ Infection

Fan¹,

Chen²,

Yu³

et al. 2012

MPMI

118

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Although there are no known sources of genetic resistance, some Citrus spp. are reportedly tolerant to huanglongbing (HLB), presumably caused by 'Candidatus Liberibacter asiaticus'. Time-course transcriptional analysis of tolerant rough lemon (Citrus jambhiri) and susceptible sweet orange (C. sinensis) in response to 'Ca. L. asiaticus' infection showed more genes differentially expressed in HLB-affected rough lemon than sweet orange at early stages but substantially fewer at late time points, possibly a critical factor underlying differences in sensitivity to 'Ca. L. asiaticus'. Pathway analysis revealed that stress responses were distinctively modulated in rough lemon and sweet orange. Although microscopic changes (e.g., callose deposition in sieve elements and phloem cell collapse) were found in both infected species, remarkably, phloem transport activity in midribs of source leaves in rough lemon was much less affected by HLB than in sweet orange. The difference in phloem cell transport activities is also implicated in the differential sensitivity to HLB between the two species. The results potentially lead to identification of key genes and the genetic mechanism in rough lemon to restrain disease development and maintain (or recover) phloem transport activity. These potential candidate genes may be used for improving citrus tolerance (or even resistance) to HLB by genetic engineering.

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Changes in carbohydrate metabolism in Citrus sinensis infected with ‘Candidatus Liberibacter asiaticus’

Cited by 125 publications

References 30 publications

Transcriptome Profiling of Citrus Fruit Response to Huanglongbing Disease

Transcriptome Profiling of Citrus Fruit Response to Huanglongbing Disease

High Incidence of Preharvest Colonization of Huanglongbing-Symptomatic Citrus sinensis Fruit by Lasiodiplodia theobromae (Diplodia natalensis) and Exacerbation of Postharvest Fruit Decay by That Fungus

Comparative Transcriptional and Anatomical Analyses of Tolerant Rough Lemon and Susceptible Sweet Orange in Response to ‘Candidatus Liberibacter asiaticus’ Infection

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