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ARS Home » Southeast Area » Fort Pierce, Florida » U.S. Horticultural Research Laboratory » Citrus and Other Subtropical Products Research » Research » Publications at this Location » Publication #315227

Title: Huanglongbing disease impacts on volatile profiles of peel oil in 'Hamlin' and 'Valencia' oranges

item YANG, HUQING - Zhejiang University
item BOURCIER, ELISE - Agro Paris Tech
item Zhao, Wei
item Plotto, Anne
item Baldwin, Elizabeth - Liz
item Bai, Jinhe
item IREY, MIKE - Southern Gardens Citrus

Submitted to: Florida State Horticultural Society Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 3/16/2015
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Orange fruit and juice from Huanglongbing (HLB) affected trees have been reported to be off-flavored, and this is the first report on volatile components of citrus peel oil affected by HLB disease. ‘Valencia’ oranges were harvested from commercial groves in South Florida. Fruit samples (26), each obtained from 3-5 visually HLB symptomatic, or asymptomatic trees were harvested, and processed for juice and peel was cold pressed to extract oil. The juice of each sample was analyzed by qPCR for the HLB presumed pathogen (Candidatus Liberibacter asiaticus, CLas) DNA, and cold-pressed peel oil volatile components were analyzed by gas chromatography-mass spectrometry (GC-MS). Based on qPCR Ct values using Li and LJ primers, samples were divided into three groups: 1) healthy (HLBh, 8 out of 15 asymptomatic samples confirmed as CLas free), 2) HLB severe (HLBs, 5 out of 11 symptomatic HLB samples were confirmed with high CLas titer), and rest of the samples that were possibly HLB affected (HLBp), with low CLas titer (6 symptomatic and 7 asymptomatic). A total of 57 volatile compounds were identified in peel oil samples, including 9 monoterpenes, 16 sesquiterpenes, 12 alcohols, 13 aldehydes, 1 alkane, 2 ketones, 2 esters, and 2 terpene oxides. Of those, 14 compounds were found to be significantly different among the three groups. Hexanal, (E,E)-2,4-decadienal, d-cadinene and a-copaene were significantly lower in HLBs samples than in the healthy samples, while sabinene, (E)-p-mentha-2,8-dien-1-ol, a-terpineneol, 3,7-dimethyl-6-octen-1-ol, (Z)-3,7-dimethyl-2,6-octadien-1-ol, carvone, cyclodecane, ß-cubebene, (E)-ß-farnesene, a-humulene and a-farnesene were significantly higher in HLBs samples. The contents of those volatiles in HLBp were in between. Principal component analysis discriminated HLBs from HLBh samples in PC2, with HLBp samples not separated from either HLBh or HLBs. Similar results shown in peel oil solvent extractions in both 'Valencia' and 'Hamlin' fruits with more components.