transport; cell death; catabolite modification; leaf senescence; chlorophyll breakdown
Das Aditi, Christ Bastien, Hörtensteiner Stefan (2018), Characterization of the pheophorbide a oxygenase/phyllobilin pathway of chlorophyll breakdown in grasses, in Planta
, 248(4), 875-892.
Christ Bastien, Hauenstein Mareike, Hörtensteiner Stefan (2016), A liquid chromatography-mass spectrometry platform for the analysis of phyllobilins, the major degradation products of chlorophyll in Arabidopsis thaliana., in The Plant journal : for cell and molecular biology
, 88(3), 505-518.
Hauenstein Mareike, Christ Bastien, Das Aditi, Aubry Sylvain, Hörtensteiner Stefan (2016), A Role for TIC55 as a Hydroxylase of Phyllobilins, the Products of Chlorophyll Breakdown during Plant Senescence, in The Plant Cell
, 28(10), 2510-2527.
Lira Bruno Silvestre, Rosado Daniele, Almeida Juliana, de Souza Amanda Pereira, Buckeridge Marcos Silveira, Purgatto Eduardo, Guyer Luzia, Hörtensteiner Stefan, Freschi Luciano, Rossi Magdalena (2016), Pheophytinase Knockdown Impacts Carbon Metabolism and Nutraceutical Content Under Normal Growth Conditions in Tomato., in Plant & cell physiology
, 57(3), 642-53.
Almeida Juliana, Azevedo Mariana da Silva, Spicher Livia, Glauser Gaétan, vom Dorp Katharina, Guyer Luzia, del Valle Carranza Andrea, Asis Ramón, de Souza Amanda Pereira, Buckeridge Marcos, Demarco Diego, Bres Cécile, Rothan Christophe, Peres Lázaro Eustáquio Pereira, Hörtensteiner Stefan, Kessler Félix, Dörmann Peter, Carrari Fernando, Rossi Magdalena (2016), Down-regulation of tomato PHYTOL KINASE strongly impairs tocopherol biosynthesis and affects prenyllipid metabolism in an organ-specific manner., in Journal of experimental botany
, 67(3), 919-34.
Sakuraba Yasuhito, Han Su-Hyun, Lee Sang-Hwa, Hörtensteiner Stefan, Paek Nam-Chon (2016), Arabidopsis NAC016 promotes chlorophyll breakdown by directly upregulating STAYGREEN1 transcription., in Plant cell reports
, 35(1), 155-66.
Süssenbacher Iris, Hörtensteiner Stefan, Kräutler Bernhard (2015), A Dioxobilin-Type Fluorescent Chlorophyll Catabolite as a Transient Early Intermediate of the Dioxobilin-Branch of Chlorophyll Breakdown in Arabidopsis thaliana., in Angewandte Chemie (International ed. in English)
, 54(46), 13777-81.
Süssenbacher Iris, Kreutz Christoph R, Christ Bastien, Hörtensteiner Stefan, Kräutler Bernhard (2015), Hydroxymethylated Dioxobilins in Senescent Arabidopsis thaliana Leaves: Sign of a Puzzling Biosynthetic Intermezzo of Chlorophyll Breakdown., in Chemistry (Weinheim an der Bergstrasse, Germany)
, 21(33), 11664-70.
Hu Xueyun, Makita Satoru, Schelbert Silvia, Sano Shinsuke, Ochiai Masanori, Tsuchiya Tohru, Hasegawa Shigeaki F, Hörtensteiner Stefan, Tanaka Ayumi, Tanaka Ryouichi (2015), Reexamination of chlorophyllase function implies its involvement in defense against chewing herbivores., in Plant physiology
, 167(3), 660-70.
Christ Bastien, Egert Aurélie, Süssenbacher Iris, Kräutler Bernhard, Bartels Dorothea, Peters Shaun, Hörtensteiner Stefan (2014), Water deficit induces chlorophyll degradation via the 'PAO/phyllobilin' pathway in leaves of homoio- (Craterostigma pumilum) and poikilochlorophyllous (Xerophyta viscosa) resurrection plants., in Plant, cell & environment
, 37(11), 2521-31.
Sakuraba Yasuhito, Kim Dami, Kim Ye-Sol, Hörtensteiner Stefan, Paek Nam-Chon (2014), Arabidopsis STAYGREEN-LIKE (SGRL) promotes abiotic stress-induced leaf yellowing during vegetative growth., in FEBS letters
, 588(21), 3830-7.
Zhang Wei, Liu Tianqi, Ren Guodong, Hörtensteiner Stefan, Zhou Yongming, Cahoon Edgar B, Zhang Chunyu (2014), Chlorophyll degradation: the tocopherol biosynthesis-related phytol hydrolase in Arabidopsis seeds is still missing., in Plant physiology
, 166(1), 70-9.
Guyer Luzia, Hofstetter Silvia Schelbert, Christ Bastien, Lira Bruno Silvestre, Rossi Magdalena, Hörtensteiner Stefan (2014), Different mechanisms are responsible for chlorophyll dephytylation during fruit ripening and leaf senescence in tomato., in Plant physiology
, 166(1), 44-56.
Sakuraba Yasuhito, Park So-Yon, Kim Ye-Sol, Wang Seung-Hyun, Yoo Soo-Cheul, Hörtensteiner Stefan, Paek Nam-Chon (2014), Arabidopsis STAY-GREEN2 is a negative regulator of chlorophyll degradation during leaf senescence., in Molecular plant
, 7(8), 1288-302.
Sakuraba Yasuhito, Lee Sang-Hwa, Kim Ye-Sol, Park Ohkmae K, Hörtensteiner Stefan, Paek Nam-Chon (2014), Delayed degradation of chlorophylls and photosynthetic proteins in Arabidopsis autophagy mutants during stress-induced leaf yellowing., in Journal of experimental botany
, 65(14), 3915-25.
Süssenbacher Iris, Christ Bastien, Hörtensteiner Stefan, Kräutler Bernhard (2014), Hydroxymethylated phyllobilins: a puzzling new feature of the dioxobilin branch of chlorophyll breakdown., in Chemistry (Weinheim an der Bergstrasse, Germany)
, 20(1), 87-92.
1. Project summary1.1. Background. Chlorophyll (Chl) degradation during leaf senescence and fruit ripening leads to the formation of colorless linear tetrapyrroles. Early reactions of breakdown within plastids are the removal of the hydrophobic phytol chain of Chl by pheophytinase and a porphyrin ring opening reaction, catalyzed by pheophorbide a oxygenase (PAO), that defines the linear tetrapyrrole structure found in the subsequent catabolites. Before import into the vacuole, where they ultimately accumulate, these catabolites are modified at defined positions, e.g. by a commonly occurring hydroxylation at the C8-2 position. 1.2. Working hypothesis. Even though Chl breakdown is rather well understood, different aspects of the pathway, such as catabolite transport within the cell and the mechanism of hydroxylation, are largely unknown. In addition, certain phenotypes of Chl catabolic mutants indicate that Chl breakdown may be related to guard cell function as well as possibly being involved in retrograde signaling. Thus, the following questions can be raised:- What are the molecular transport systems that transport Chl catabolites from plastids to the vacuole?- By which mechanism/enzyme are Chl catabolites hydroxylated?- Is there a link between Chl breakdown and guard cell function?- How does light-independent cell death occur in PAO mutants?1.3. Specific aims. This proposal addresses different aspects of Chl breakdown and has the following aims:- Elucidating the molecular mechanism of Chl catabolite export from plastids- Elucidating the molecular mechanism of Chl catabolite import into the vacuole- Characterizing Chl catabolite hydroxylation- Analyzing whether Chl breakdown plays a role in stomata function- Analyzing light-independent cell death regulation in PAO mutants1.4. Methods. Performing the experiments proposed here involves a variety of molecular, biochemical and analytical methods, such as (i) mutant identification, crossing and analysis, (ii) production of transgenic plants, (iii) expression and enzymatic analysis of enzymes, (iv) chromatographic methods, (v) pigment and protein identification and/or structure analysis techniques, and (vi) confocal microscopy.1.5. Expected value of the proposed project. This proposal addresses a few important aspects of Chl breakdown. The elucidation of transporters will provide molecular insight into intracellular transport mechanism of Chl catabolites and will possibly also elucidate the unknown mechanism of chloroplast export of phytochromobilin, the phytochrome chromophor. Recently, stomata were recognized as being important sites for regulating leaf senescence. The planned research will add to this by elucidating whether/to what extent Chl breakdown in guard cells is important. Finally, this proposal aims at elucidating a cell death signaling mechanism that is related to Chl breakdown and may be triggered by a plastid-localized breakdown intermediate. Thus, the results of this part may add to the highly interesting field of retrograde signaling.