title: Nucleotides, micro- and macro-nutrients, limonoids, flavonoids, and hydroxycinnamates composition in the phloem sap of sweet orange.
abstract: Currently, the global citrus production is declining due to the spread of Huanglongbing (HLB). HLB, otherwise known as citrus greening, is caused by Candidatus Liberibacter asiaticus (CLas) and is transmitted by the Asian citrus psyllids (ACP), Diaphorina citri Kuwayama. ACP transmits CLas bacterium while feeding on the citrus phloem sap. Multiplication of CLas in the phloem of citrus indicates that the sap contains all the essential nutrients needed for CLas. In this study, we investigated the micro- and macro-nutrients, nucleotides, and others secondary metabolites of phloem sap from pineapple sweet orange. The micro- and macro-nutrients were analyzed using inductively coupled plasma-mass spectroscopy (ICP-MS) and inductively coupled plasma-optical emission spectroscopy (ICP-OES). Nucleotides and other secondary metabolites analysis was accomplished by reversed phase HPLC coupled with UV, fluorescence detection, or negative mode electrospray ionization mass spectrometry (ESI-MS). Calcium (89 mM) was the highest element followed by potassium (38.8 mM) and phosphorous (24 mM). Magnesium and sulfur were also abundant and their concentrations were 15 and 9 mM, respectively. The rest of the elements were found in low amounts (< 2mM). The concentrations of ATP, ADP, and AMP were 16, 31, and 3 µ mole/Kg fwt, respectively. GTP, GMP. NAD, FMN, FAD, and riboflavin were found at concentrations below (3 µ mole/Kg fwt). The phloem was rich in nomilin 124 mM and limonin 176 µ mole/Kg fwt. Hesperidin, vicenin-2, sinensetin, and nobiletin were the most predominant flavonoids. In addition, several hydroxycinnamates were detected. The results of this study will increase our knowledge about the nature and the chemical composition of citrus phloem sap.
authors.affiliation: a Citrus Research and Education Center, University of Florida, IFAS , Lake Alfred , FL , USA.
authors.forename: Faraj
authors.initials: F
authors.lastname: Hijaz
authors.affiliation: b US Horticultural Research Laboratory, USDA, ARS , Fort Pierce , FL , USA.
authors.forename: John A
authors.initials: JA
authors.lastname: Manthey
authors.affiliation: c Department of Diagnostic Medicine/Pathobiology , Kansas State Veterinary Diagnostic Laboratory, Kansas State University , Manhattan , KS , USA.
authors.forename: Deon
authors.initials: D
authors.lastname: Van der Merwe
authors.affiliation: a Citrus Research and Education Center, University of Florida, IFAS , Lake Alfred , FL , USA.
authors.forename: Nabil
authors.initials: N
authors.lastname: Killiny
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D032084:Citrus sinensis / Q000737:chemistry* / Q000382:microbiology / Q000469:parasitology; D003067:Coenzymes / Q000032:analysis; D003373:Coumaric Acids / Q000032:analysis*; D004602:Elements; D005419:Flavonoids / Q000032:analysis*; D006430:Hemiptera; D036701:Limonins / Q000032:analysis*; D009705:Nucleosides / Q000032:analysis; D009711:Nucleotides / Q000032:analysis*; D052585:Phloem / Q000737:chemistry*; D012015:Reference Standards; D012230:Rhizobiaceae / Q000254:growth & development; D012256:Riboflavin / Q000032:analysis; D064210:Secondary Metabolism; D021241:Spectrometry, Mass, Electrospray Ionization; D013054:Spectrophotometry, Atomic
chemical_list: D000596:Amino Acids; D003067:Coenzymes; D003373:Coumaric Acids; D004602:Elements; D005419:Flavonoids; D036701:Limonins; D009705:Nucleosides; D009711:Nucleotides; D000255:Adenosine Triphosphate; D012256:Riboflavin
keywords: Candidatus liberibacter asiaticus; flavonoids; huanglongbing; hydroxycinnamates; limonoids; nucleotides; phloem sap composition; sweet orange