title: Differences in gene expression between natural and artificially induced leaf senescence in barley.
abstract: Senescence is the last step of leaf development in the life span of an annual plant. Senescence can be induced prematurely by treating leaf tissues with jasmonic acid methyl ester (methyl jasmonate, MeJA). During both senescence programmes, drastic changes occur at the biochemical, cellular and ultra-structural levels that were compared here for primary leaves of barley (Hordeum vulgare L.). Our findings indicate that both types of senescence are similar with respect to the morphological changes including the loss of chlorophyll, disintegration of thylakoids, and formation of plastoglobules. However, the time elapsed for reaching senescence completion was different and ranged from 7 to 8 days for artificially senescing, MeJA-treated plants to 7-8 weeks for naturally senescing plants. Pulse-labelling studies along with RNA and protein gel blot analyses showed differential changes in the expression of both plastid and nuclear genes coding for photosynthetic proteins. Several unique messenger products accumulated in naturally and artificially senescing, MeJA-treated leaves. Detailed expression and crosslinking studies revealed that pheophorbide a oxygenase (PAO), a previously implicated key enzyme of chlorophyll breakdown, is most likely not rate-limiting for chlorophyll destruction under both senescence conditions. Metabolite profiling identified differential changes in the composition of carotenoid derivatives and prenyl-lipids to occur in naturally senescing and artificially senescing plants that underscored the differences between both senescence programmes.
authors: Universität Bayreuth, Universitätsstrasse 30, D-95440 Bayreuth, Germany.
authors: Armin
authors: A
authors: Springer
authors: Universität Bayreuth, Universitätsstrasse 30, D-95440 Bayreuth, Germany.
authors: Georg
authors: G
authors: Acker
authors: Universität Bayreuth, Universitätsstrasse 30, D-95440 Bayreuth, Germany.
authors: Sandra
authors: S
authors: Bartsch
authors: Universität Bayreuth, Universitätsstrasse 30, D-95440 Bayreuth, Germany.
authors: Heike
authors: H
authors: Bauerschmitt
authors: Université Joseph Fourier, LBFA, BP53, F-38041 Grenoble cedex 9, France. Electronic address: sreinbot@ujf-grenoble.fr.
authors: Steffen
authors: S
authors: Reinbothe
authors: Universität Bayreuth, Universitätsstrasse 30, D-95440 Bayreuth, Germany.
authors: Christiane
authors: C
authors: Reinbothe
mesh_terms: D000085:Acetates / Q000494:pharmacology; D002467:Cell Nucleus / Q000187:drug effects / Q000235:genetics; D002734:Chlorophyll / Q000378:metabolism; D003517:Cyclopentanes / Q000494:pharmacology; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D001467:Hordeum / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development*; D010105:Oxygenases / Q000378:metabolism; D054883:Oxylipins / Q000494:pharmacology; D018515:Plant Leaves / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development* / Q000648:ultrastructure; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D026082:Singlet Oxygen / Q000378:metabolism; D020524:Thylakoids / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D019207:beta Carotene / Q000378:metabolism
chemical_list: D000085:Acetates; D003517:Cyclopentanes; D054883:Oxylipins; D010940:Plant Proteins; D012333:RNA, Messenger; D019207:beta Carotene; D002734:Chlorophyll; D026082:Singlet Oxygen; C072239:methyl jasmonate; D010105:Oxygenases; C112915:pheide a oxygenase
keywords: Chlorophyll breakdown; Chloroplast destruction; Methyl jasmonate-induced and natural senescence; Plastoglobules; Thylakoid membrane disassembly