Janssen, Ludovicus Hubertus Jan

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Proceedings - University of Groningen

   University of GroningenTemperature dependence of chlorophyll fluorescence induction in plant leavesJanssen, Ludovicus Hubertus JanIMPORTANT NOTE: You are advised to consult the publisher's version (publisher's PDF) if you wish to cite fromit. Please check the document version below.Document VersionPublisher's PDF, also known as Version of recordPublication date:1995Link to publication in University of Groningen/UMCG research databaseCitation for published version (APA):Janssen, L. H. J. (1995). Temperature dependence of chlorophyll fluorescence induction in plant leaves:Mechanisms and practical application. s.n.CopyrightOther than for strictly personal use, it is not permitted to download or to forward/distribute the text or part of it without the consent of theauthor(s) and/or copyright holder(s), unless the work is under an open content license (like Creative Commons).The publication may also be distributed here under the terms of Article 25fa of the Dutch Copyright Act, indicated by the “Taverne” license.More information can be found on the University of Groningen website: https://www.rug.nl/library/open-access/self-archiving-pure/taverne-amendment.Take-down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediatelyand investigate your claim.Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons thenumber of authors shown on this cover page is limited to 10 maximum.Download date: 12-10-2022SummaryGrowth and production of crops is preceded by a light dependent process convertingcarbondioxide (COr) from the air and water to sugars and oxygen (Or): photosynthesis. Thefirst reactions of photosynthesis occur in two protein-pigment complexes, the photosystemsI and IL These complexes aÍe situated in the membranes of the chloroplast: the thylakoids.The absorption of lightenergy in the photosystems induces chemical reactions resulting in thefixation of COr. Both growth and photosynthesis are affected by temperature. This thesisevaluates the possibility to assess limitation of growth by low temperatures at the level of thephotosystems. Therefore, temperature effects on the functioning of the photosystems werestudied and related to genetic variation in low temperature sensitivity of plants.Part of the absorbed light energy is lost for the plant by heat and chlorophyll fluorescenceproduction. The amount of emitted chlorophyll fluorescence is a measure for the Íïnctioningof the photosystems, at room temperature primarily for the functioning of photosystem II.I ess efficient chemical fixation of light energy results in more emission of chlorophyllfluorescence.Temperature eÍfects on the functioning of the photosystems were studied by brieflyinducing chlorophyll fluorescence by low light and at different temperatures. The maximumfluorescence of induction curves ($) was determined for leaf discs. Fo reflects a maximalreduction of the quinone electron acceptor of photosystem II, Q,. This acceptor is reduced byphotosystem II activity and oxidised by photosystem I activity. The temperature dependenceof both processes determines the extent of Qo reduction and thus the level of Fo. Between 0'Cand 30'C two discontinuities were found in F, versus temperature curves: a low temperaturebreak (l7B) and a high temperature break (É1ZB). Fp decreased from OoC to the temperatureof LTB, and from the temperature of HTB to 30oC.LTB was absent when photosynthetic electron transport was inhibited, whtle HTB remained.LTB also depended on the light intensity used to induce chlorophyll fluorescence. Increasingthe light intensity from 10 to 150pmo1 m-2s-1 resulted in the disappearance of tZB. Theseresults were found for cucumber and tomato (chapters 4 and 5) and indicate a limitation inelectron transport beyond photosystem II at temperatures below the LTB temperature and adecrease of the efficiency of light energy capture of photosystem II at temperatures above theI17B temperature. This interpretation was sustained for tomato by an analysis of otherfluorescence parameters (chapter 6).In addition, the temperature dependence of net CO2 fixation of cucumber and tomato leafdiscs was determined (chapters 4 and 5). Net CO, fixation rates exceeded 90Vo of themaximal value found between the temperatures of LZB and HTB. The temperatures of LZBand HTB indicate the temperature range for optimal functioning of photosynthesis, althoughphotosynthetic activity at steady state is not limited by electron transport.99The limitation in photosynthetic electron transport at temperatures below the LTBtemperature may be caused by local phase transitions in the lipid matrix ol' the thylakoidmembrane by the transition of domains Íiom the liquid-crystalline to the rigid gel phase. Geldomains in the thylakoid membrane will limit lateral diÍÍïsion in the rnembrane of theelectron carrier plastoquinone and thus inhibit photosynthetic electron transport. Thisinterpretation is sustained by the similar temperatures íbund for LTB and for phasc transitionsof lipids, reported in the literature (chapter 1, 4 and 5).The decreased efficiency of light energy oapture oí photosystem II at temperatures abovethe HTB temperature corresponded with alterations in photosystem II heterogeneity(chapter 6). The fraction reaclion centers with a relatively small antenna increased at theexpense of reaction centers with a relatively large antenna.The perspectives for the use of chlorophyll Íluorescence measurements o1'leaves to assesslow temperature sensitivity of plants was studied. DiÍferences rn LTB and HTB temperaturesbetween species (chrysant, spinach, cucumber and tomato) and between genotypes oi onespecies (cucumber and tomato) were related to difíèrences in low tcmper:lture scnsiLivity(chapter 3). Thc low temperature tolerant chrysant showed no LTB bctwcen 0' and 30oC. ThcLTB temperatures of the remaining species were lower in accordanoe with low tcmpcraturcsensitivity. For tomato, a lower growth temperature resulted in a lowcr LZrg ten.rperatr:re,while the HTB temperature remained constant. The temperature of HTB was lower wher.r thclight intensity during growth was decrcased (chapter 3).If less low temperature sensitive genotypcs would be available encrgy costs lbr thccultivation of horticultural crops in greenhouses could be saved. For thc improvcment olbreeding such genotypes a fast method to screen genotypes on their low tempcraturcsensitivity is very desirable. Chapter 2 describes equipment, developcd during the prcscntinvestigations, to measure the temperaturc dependence of chlorophyll íluoresccnce ir.rductionin a relatively short time and for a large number of samples. Chaptcr 7 describes anexperiment to test the application of the temperature dependent chlorophyll Íluoresccnccmethod to select less low tempcraturc sensitive tomato gcnotypes. Chlorophyll lluorescenccmeasuÍements could discrirninate between 8 genotypcs with rcgard to thcir telnpcraturcsensitivity of the thylakoid rncmbrane. This discrimination did not correspond with ger-reticdifferences in net CO, fixation ratcs oÍ leavcs, nor with genetic diÍfcrences in rclativc growthrates at low temperature and low light. A Ílnal conclusion rcgarding thc application o1'themethod could not yet be givcn based on thc results of this experiment due to a lirritcd gcneticvariation in growth of the studied tomato genotypes and duc to dilficulties in asscssingsenetic difÍ'erences in low temoerlture sensitivitv.100

Temperature dependence of chlorophyll fluorescence induction in plant leaves:Mechanisms and practical application

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Temperature dependence of chlorophyll fluorescence induction in plant leaves:Mechanisms and practical application

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