title: Metabolic changes in Citrus leaf volatiles in response to environmental stress.
abstract: Citrus plants are well known as a rich source of VOCs, and several have important roles in defense responses. However, how VOCs are regulated in response to environmental stress is not yet well understood. In this study, we investigated dynamic changes of VOCs present in leaves of seven Citrus species (Citrus sinensis, C. limon, C. paradisi, C. unshiu, C. kinokuni, C. grandis, and C. hassaku) in response to mechanical wounding, jasmonic acid (JA), and salicylic acid (SA) as determined by gas chromatography/mass spectrometric analysis followed by multivariate analysis (principal component analysis, PCA, and orthogonal partial least squares-discriminant analysis, OPLS-DA). PCA and OPLS-DA suggested that changes in VOC profiles against stress stimuli were much diverse among Citrus species. OPLS-DA showed that C6 volatiles, such as hexanal and trans-2-hexenal, were induced in response to JA and SA stimuli in C. sinensis and C. grandis, while the other VOCs were decreased under all tested stress conditions. α-Farnesene was induced in all species except C. hassaku after wounding or JA treatment. In addition, α-farnesene was also induced in response to SA stimuli in C. unshiu and C. kinokuni. Therefore these volatiles can be candidates of the common stress biomarkers in Citrus. Our results will give a new insight into defense mechanisms in Citrus species.
authors.affiliation: Graduated School of Biology-Oriented Science and Technology, Kinki University, 930 Nishimitani, Kinokawa City, Wakayama, 649-6493, Japan.
authors.forename: Tomonori
authors.initials: T
authors.lastname: Asai
authors.affiliation: Graduated School of Biology-Oriented Science and Technology, Kinki University, 930 Nishimitani, Kinokawa City, Wakayama, 649-6493, Japan; Experimental Farm, Kinki University, Yuasa, Yuasa-cho, Arida-gun, Wakayama, 643-0004, Japan.
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Matsukawa
authors.affiliation: Graduated School of Biology-Oriented Science and Technology, Kinki University, 930 Nishimitani, Kinokawa City, Wakayama, 649-6493, Japan. Electronic address: kajiyama@waka.kindai.ac.jp.
authors.forename: Shin'ichiro
authors.initials: S
authors.lastname: Kajiyama
mesh_terms: D000447:Aldehydes / Q000378:metabolism; D002957:Citrus / Q000187:drug effects / Q000378:metabolism*; D003517:Cyclopentanes / Q000494:pharmacology; D004777:Environment; D054883:Oxylipins / Q000494:pharmacology; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism*; D020156:Salicylic Acid / Q000378:metabolism; D012717:Sesquiterpenes / Q000494:pharmacology; D013312:Stress, Physiological; D055549:Volatile Organic Compounds / Q000378:metabolism*
chemical_list: D000447:Aldehydes; D003517:Cyclopentanes; D054883:Oxylipins; D012717:Sesquiterpenes; D055549:Volatile Organic Compounds; C062672:alpha-farnesene; C051750:2-hexenal; C011006:jasmonic acid; D020156:Salicylic Acid
keywords: Citrus; Environmental stress; Metabolomics; Multivariate analysis; Volatiles