title: Coupling a branch enclosure with differential mobility spectrometry to isolate and measure plant volatiles in contained greenhouse settings.
abstract: Volatile organic compounds (VOCs) are off-gassed from all living organisms and represent end products of metabolic pathways within the system. In agricultural systems, these VOCs can provide important information on plant health and can ordinarily be measured non-invasively without harvesting tissue from the plants. Previously we reported a portable gas chromatography/differential mobility spectrometry (GC/DMS) system that could distinguish VOC profiles of pathogen-infected citrus from healthy trees before visual symptoms of disease were present. These measurements were taken directly from canopies in the field, but the sampling and analysis protocol did not readily transfer to a controlled greenhouse study where the ambient background air was saturated with volatiles contained in the facility. In this study, we describe for the first time a branch enclosure uniquely coupled with GC/DMS to isolate and measure plant volatiles. To test our system, we sought to replicate our field experiment within a contained greenhouse and distinguish the VOC profiles of healthy versus citrus infected with Candidatus Liberibacter asiaticus. We indeed confirm the ability to track infection-related trace biogenic VOCs using our sampling system and method and we now show this difference in Lisbon lemons (Citrus×limon L. Burm. f.), a varietal not previously reported. Furthermore, the system differentiates the volatile profiles of Lisbon lemons from Washington navels [Citrus sinensis (L.) Osbeck] and also from Tango mandarins (Citrus reticulata Blanco). Based on this evidence, we believe this enclosure-GC/DMS system is adaptable to other volatile-based investigations of plant diseases in greenhouses or other contained settings, and this system may be helpful for basic science research studies of infection mechanisms.
authors.affiliation: Mechanical and Aerospace Engineering, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA.
authors.forename: Mitchell M
authors.initials: MM
authors.lastname: McCartney
authors.affiliation: Mechanical and Aerospace Engineering, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA.
authors.forename: Sierra L
authors.initials: SL
authors.lastname: Spitulski
authors.affiliation: Mechanical and Aerospace Engineering, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA.
authors.forename: Alberto
authors.initials: A
authors.lastname: Pasamontes
authors.affiliation: Mechanical and Aerospace Engineering, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Peirano
authors.affiliation: Mechanical and Aerospace Engineering, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Schirle
authors.affiliation: Mechanical and Aerospace Engineering, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA.
authors.forename: Raquel
authors.initials: R
authors.lastname: Cumeras
authors.affiliation: Mechanical and Aerospace Engineering, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA.
authors.forename: Jason D
authors.initials: JD
authors.lastname: Simmons
authors.affiliation: Mechanical and Aerospace Engineering, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA.
authors.forename: Jeffrey L
authors.initials: JL
authors.lastname: Ware
authors.affiliation: Mechanical and Aerospace Engineering, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA.
authors.forename: Joshua F
authors.initials: JF
authors.lastname: Brown
authors.affiliation: Mechanical and Aerospace Engineering, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA.
authors.forename: Alexandria J Y
authors.initials: AJ
authors.lastname: Poh
authors.affiliation: Mechanical and Aerospace Engineering, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA.
authors.forename: Seth C
authors.initials: SC
authors.lastname: Dike
authors.affiliation: Contained Research Facility, University of California, Davis, 555 Hopkins Road, Davis, CA 95616, USA.
authors.forename: Elizabeth K
authors.initials: EK
authors.lastname: Foster
authors.affiliation: Contained Research Facility, University of California, Davis, 555 Hopkins Road, Davis, CA 95616, USA.
authors.forename: Kristine E
authors.initials: KE
authors.lastname: Godfrey
authors.affiliation: Mechanical and Aerospace Engineering, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA. Electronic address: cedavis@ucdavis.edu.
authors.forename: Cristina E
authors.initials: CE
authors.lastname: Davis
mesh_terms: D002957:Citrus / Q000737:chemistry* / Q000254:growth & development; D004780:Environment, Controlled; D006813:Humidity; D013057:Spectrum Analysis / Q000379:methods*; D055549:Volatile Organic Compounds / Q000032:analysis* / Q000737:chemistry / Q000302:isolation & purification*
chemical_list: D055549:Volatile Organic Compounds
keywords: Candidatus Liberibacter asiaticus (CLas); Differential mobility spectrometry (DMS); Field asymmetric ion mobility spectrometry (FAIMS); Huanglongbing (HLB); Volatile organic compounds (VOCs)