title: Pathogen-Induced Leaf Chlorosis: Products of Chlorophyll Breakdown Found in Degreened Leaves of Phytoplasma-Infected Apple (Malus × domestica Borkh.) and Apricot (Prunus armeniaca L.) Trees Relate to the Pheophorbide a Oxygenase/Phyllobilin Pathway.
abstract: Phytoplasmoses such as apple proliferation (AP) and European stone fruit yellows (ESFY) cause severe economic losses in fruit production. A common symptom of both phytoplasma diseases is early yellowing or leaf chlorosis. Even though chlorosis is a well-studied symptom of biotic and abiotic stresses, its biochemical pathways are hardly known. In particular, in this context, a potential role of the senescence-related pheophorbide a oxygenase/phyllobilin (PaO/PB) pathway is elusive, which degrades chlorophyll (Chl) to phyllobilins (PBs), most notably to colorless nonfluorescent Chl catabolites (NCCs). In this work, we identified the Chl catabolites in extracts of healthy senescent apple and apricot leaves. In extracts of apple tree leaves, a total of 12 Chl catabolites were detected, and in extracts of leaves of the apricot tree 16 Chl catabolites were found. The seven major NCC fractions in the leaves of both fruit tree species were identical and displayed known structures. All of the major Chl catabolites were also found in leaf extracts from AP- or ESFY-infected trees, providing the first evidence that the PaO/PB pathway is relevant also for pathogen-induced chlorosis. This work supports the hypothesis that Chl breakdown in senescence and phytoplasma infection proceeds via a common pathway in some members of the Rosaceae family.
authors.affiliation: Laimburg Research Center , Laimburg 6 - Pfatten (Vadena), 39040 Auer (Ora), BZ, Italy.
authors.forename: Cecilia
authors.initials: C
authors.lastname: Mittelberger
authors.affiliation: Institute of Organic Chemistry and Center of Molecular Biosciences, University of Innsbruck , Innrain 80/82, 6020 Innsbruck, Austria.
authors.forename: Hacer
authors.initials: H
authors.lastname: Yalcinkaya
authors.affiliation: Laimburg Research Center , Laimburg 6 - Pfatten (Vadena), 39040 Auer (Ora), BZ, Italy.
authors.forename: Christa
authors.initials: C
authors.lastname: Pichler
authors.affiliation: Institute of Organic Chemistry and Center of Molecular Biosciences, University of Innsbruck , Innrain 80/82, 6020 Innsbruck, Austria.
authors.forename: Johanna
authors.initials: J
authors.lastname: Gasser
authors.affiliation: Institute of Organic Chemistry and Center of Molecular Biosciences, University of Innsbruck , Innrain 80/82, 6020 Innsbruck, Austria.
authors.forename: Gerhard
authors.initials: G
authors.lastname: Scherzer
authors.affiliation: Institute of Organic Chemistry and Center of Molecular Biosciences, University of Innsbruck , Innrain 80/82, 6020 Innsbruck, Austria.
authors.forename: Theresia
authors.initials: T
authors.lastname: Erhart
authors.affiliation: Laimburg Research Center , Laimburg 6 - Pfatten (Vadena), 39040 Auer (Ora), BZ, Italy.
authors.forename: Sandra
authors.initials: S
authors.lastname: Schumacher
authors.affiliation: Laimburg Research Center , Laimburg 6 - Pfatten (Vadena), 39040 Auer (Ora), BZ, Italy.
authors.forename: Barbara
authors.initials: B
authors.lastname: Holzner
authors.affiliation: Laimburg Research Center , Laimburg 6 - Pfatten (Vadena), 39040 Auer (Ora), BZ, Italy.
authors.forename: Katrin
authors.initials: K
authors.lastname: Janik
authors.affiliation: Laimburg Research Center , Laimburg 6 - Pfatten (Vadena), 39040 Auer (Ora), BZ, Italy.
authors.forename: Peter
authors.initials: P
authors.lastname: Robatscher
authors.affiliation: Institute of Organic Chemistry and Center of Molecular Biosciences, University of Innsbruck , Innrain 80/82, 6020 Innsbruck, Austria.
authors.forename: Thomas
authors.initials: T
authors.lastname: Müller
authors.affiliation: Institute of Organic Chemistry and Center of Molecular Biosciences, University of Innsbruck , Innrain 80/82, 6020 Innsbruck, Austria.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Kräutler
authors.affiliation: Laimburg Research Center , Laimburg 6 - Pfatten (Vadena), 39040 Auer (Ora), BZ, Italy.
authors.forename: Michael
authors.identifier: http://orcid.org/0000-0002-9989-7297
authors.initials: M
authors.lastname: Oberhuber
mesh_terms: D002734:Chlorophyll / Q000031:analogs & derivatives* / Q000378:metabolism*; D027845:Malus / Q000378:metabolism / Q000382:microbiology*; D010105:Oxygenases / Q000378:metabolism*; D045582:Phytoplasma / Q000502:physiology*; D010935:Plant Diseases / Q000382:microbiology*; D018515:Plant Leaves / Q000378:metabolism / Q000382:microbiology; D010940:Plant Proteins / Q000378:metabolism*; D000068219:Prunus armeniaca / Q000378:metabolism / Q000382:microbiology*; D014197:Trees / Q000378:metabolism / Q000382:microbiology
chemical_list: D010940:Plant Proteins; D002734:Chlorophyll; D010105:Oxygenases; C032623:pheophorbide a
keywords: European stone fruit yellows; apple proliferation; chlorophyll; chlorophyll catabolites; phytoplasma