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An HPLC-MS characterization of the changes in sweet orange leaf metabolite profile following infection by the bacterial pathogen Candidatus Liberibacter asiaticus.

Hijaz FM, Manthey JA, Folimonova SY, Davis CL, Jones SE, Reyes-De-Corcuera JI - PLoS ONE (2013)

Bottom Line: Included among these compounds are flavonoid glycosides, polymethoxylated flavones, and hydroxycinnamates.Four structurally related hydroxycinnamate compounds increased more than 10-fold in leaves from 'Hamlin' and 'Valencia' sweet orange trees in response to Clas infection.Possible roles of these hydroxycinnamates as plant defense compounds against the Clas infection are discussed.

View Article: PubMed Central - PubMed

Affiliation: IFAS, Citrus Research and Education Center, University of Florida, Lake Alfred, Florida, United States of America.

ABSTRACT
Huanglongbing (HLB) presumably caused by Candidatus Liberibacter asiaticus (CLas) threatens the commercial U.S. citrus crop of an annual value of $3 billion. The earliest shift in metabolite profiles of leaves from greenhouse-grown sweet orange trees infected with Clas, and of healthy leaves, was characterized by HPLC-MS concurrently with PCR testing for the presence of Clas bacteria and observation of disease symptoms. Twenty, 8-month-old 'Valencia' and 'Hamlin' trees were grafted with budwood from PCR-positive HLB source trees. Five graft-inoculated trees of each variety and three control trees were sampled biweekly and analyzed by HPLC-MS and PCR. Thirteen weeks after inoculation, Clas was detected in newly growing flushes in 33% and 55% of the inoculated 'Hamlin' and 'Valencia' trees, respectively. Inoculated trees remained asymptomatic in the first 20 weeks, but developed symptoms 30 weeks after grafting. No significant differences in the leaf metabolite profiles were detected in Clas-infected trees 23 weeks after inoculation. However, 27 weeks after inoculation, differences in metabolite profiles between control leaves and those of Clas-infected trees were evident. Affected compounds were identified with authentic standards or structurally classified by their UV and mass spectra. Included among these compounds are flavonoid glycosides, polymethoxylated flavones, and hydroxycinnamates. Four structurally related hydroxycinnamate compounds increased more than 10-fold in leaves from 'Hamlin' and 'Valencia' sweet orange trees in response to Clas infection. Possible roles of these hydroxycinnamates as plant defense compounds against the Clas infection are discussed.

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Related in: MedlinePlus

Principal component analysis of HPLC-MS leaf metabolites from ‘Valencia’ and ‘Hamlin’ trees.A) score plot of leaf metabolites from ‘Valencia’ trees 3 weeks after inoculation; B) score plot of leaf metabolites from ‘Hamlin’ trees 3 weeks after inoculation; C) score plot of leaf metabolites from ‘Valencia’ trees 38 weeks after inoculation; D) score plot of leaf metabolites from ‘Hamlin’ trees 38 weeks after inoculation.
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pone-0079485-g004: Principal component analysis of HPLC-MS leaf metabolites from ‘Valencia’ and ‘Hamlin’ trees.A) score plot of leaf metabolites from ‘Valencia’ trees 3 weeks after inoculation; B) score plot of leaf metabolites from ‘Hamlin’ trees 3 weeks after inoculation; C) score plot of leaf metabolites from ‘Valencia’ trees 38 weeks after inoculation; D) score plot of leaf metabolites from ‘Hamlin’ trees 38 weeks after inoculation.

Mentions: Principal component analysis (PCA) and the t-test were carried out on each set of leaf samples to compare the metabolite profiles of the control to those from Clas-inoculated trees and to identify compounds whose relative amounts were significantly affected by the progression of HLB disease. The PCA and t-test are the most common statistical analysis approach used in untargeted large-scale plant metabolomics studies [28,29]. No group clustering was observed in the score plots from PCA of ‘Valencia’ leaf metabolites during the first 23 weeks (data not shown). However, at 27 weeks, clustering into two groups (HLB and control) began to form (data not shown), and the clustering was well-defined by 38 weeks (Figure 4C). Loading values from PCA for the first or second principal components (Table 4) of compound 6, 7, 9, and 20, were greatest, suggesting that they were responsible for the group clustering.


An HPLC-MS characterization of the changes in sweet orange leaf metabolite profile following infection by the bacterial pathogen Candidatus Liberibacter asiaticus.

Hijaz FM, Manthey JA, Folimonova SY, Davis CL, Jones SE, Reyes-De-Corcuera JI - PLoS ONE (2013)

Principal component analysis of HPLC-MS leaf metabolites from ‘Valencia’ and ‘Hamlin’ trees.A) score plot of leaf metabolites from ‘Valencia’ trees 3 weeks after inoculation; B) score plot of leaf metabolites from ‘Hamlin’ trees 3 weeks after inoculation; C) score plot of leaf metabolites from ‘Valencia’ trees 38 weeks after inoculation; D) score plot of leaf metabolites from ‘Hamlin’ trees 38 weeks after inoculation.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3818228&req=5

pone-0079485-g004: Principal component analysis of HPLC-MS leaf metabolites from ‘Valencia’ and ‘Hamlin’ trees.A) score plot of leaf metabolites from ‘Valencia’ trees 3 weeks after inoculation; B) score plot of leaf metabolites from ‘Hamlin’ trees 3 weeks after inoculation; C) score plot of leaf metabolites from ‘Valencia’ trees 38 weeks after inoculation; D) score plot of leaf metabolites from ‘Hamlin’ trees 38 weeks after inoculation.
Mentions: Principal component analysis (PCA) and the t-test were carried out on each set of leaf samples to compare the metabolite profiles of the control to those from Clas-inoculated trees and to identify compounds whose relative amounts were significantly affected by the progression of HLB disease. The PCA and t-test are the most common statistical analysis approach used in untargeted large-scale plant metabolomics studies [28,29]. No group clustering was observed in the score plots from PCA of ‘Valencia’ leaf metabolites during the first 23 weeks (data not shown). However, at 27 weeks, clustering into two groups (HLB and control) began to form (data not shown), and the clustering was well-defined by 38 weeks (Figure 4C). Loading values from PCA for the first or second principal components (Table 4) of compound 6, 7, 9, and 20, were greatest, suggesting that they were responsible for the group clustering.

Bottom Line: Included among these compounds are flavonoid glycosides, polymethoxylated flavones, and hydroxycinnamates.Four structurally related hydroxycinnamate compounds increased more than 10-fold in leaves from 'Hamlin' and 'Valencia' sweet orange trees in response to Clas infection.Possible roles of these hydroxycinnamates as plant defense compounds against the Clas infection are discussed.

View Article: PubMed Central - PubMed

Affiliation: IFAS, Citrus Research and Education Center, University of Florida, Lake Alfred, Florida, United States of America.

ABSTRACT
Huanglongbing (HLB) presumably caused by Candidatus Liberibacter asiaticus (CLas) threatens the commercial U.S. citrus crop of an annual value of $3 billion. The earliest shift in metabolite profiles of leaves from greenhouse-grown sweet orange trees infected with Clas, and of healthy leaves, was characterized by HPLC-MS concurrently with PCR testing for the presence of Clas bacteria and observation of disease symptoms. Twenty, 8-month-old 'Valencia' and 'Hamlin' trees were grafted with budwood from PCR-positive HLB source trees. Five graft-inoculated trees of each variety and three control trees were sampled biweekly and analyzed by HPLC-MS and PCR. Thirteen weeks after inoculation, Clas was detected in newly growing flushes in 33% and 55% of the inoculated 'Hamlin' and 'Valencia' trees, respectively. Inoculated trees remained asymptomatic in the first 20 weeks, but developed symptoms 30 weeks after grafting. No significant differences in the leaf metabolite profiles were detected in Clas-infected trees 23 weeks after inoculation. However, 27 weeks after inoculation, differences in metabolite profiles between control leaves and those of Clas-infected trees were evident. Affected compounds were identified with authentic standards or structurally classified by their UV and mass spectra. Included among these compounds are flavonoid glycosides, polymethoxylated flavones, and hydroxycinnamates. Four structurally related hydroxycinnamate compounds increased more than 10-fold in leaves from 'Hamlin' and 'Valencia' sweet orange trees in response to Clas infection. Possible roles of these hydroxycinnamates as plant defense compounds against the Clas infection are discussed.

Show MeSH
Related in: MedlinePlus