Učinak visokog intenziteta svjetlosti na okruglolisnu rosiku (Drosera rotundifolia L.)

master's thesis

• Author: Martina Mužic
• Mentor: Mirta Tkalec (mentor)
• Committee member: Mirta Tkalec (predsjednik povjerenstva)
• Committee member: Ines Radanović (član povjerenstva)
• Committee member: Zora Popović (član povjerenstva)
• Committee member: Vesna Petrović Peroković (član povjerenstva)
• Granter: University of Zagreb; Faculty of Science; (Department of Biology); Zagreb
• Defense date and country: 2014-09-25, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Biology

Abstract

Okruglolisna rosika (Drosera rotundifolia L.) mesojedna je biljka koja nastanjuje rijetka cretna staništa u Hrvatskoj kojima prijeti nestajanje. Metodom košnje visoke vegetacije pokušava se spriječiti zarašćivanje cretova, pri čemu se biljke prilagođene na uvjete sjene naglo izlažu uvjetima visokog intenziteta svjetlosti. Cilj ovog istraživanja bio je utvrditi promjene u učinkovitosti fotosinteze te promjene u sadržaju i sastavu fotosintetskih pigmenata i fenolnih spojeva nakon što rosike, koje smo uzgojili u uvjetima sjene, izložimo visokom intenzitetu svjetlosti (700 ± 20 μmol fotona m-2 s-1) u trajanju od 5, 30, 50 i 100 sati. Nakon izlaganja biljke koje su 5 i 100 sati bile izložene visokom intenzitetu svjetlosti, stavljene su 7 dana na oporavak u uvjete niskog intenziteta svjetla. Kontrolna grupa biljaka bila je izložena niskom intenzitetu svjetlosti (40 ± 20 μmol fotona m-2 s-1) te je predstavljala biljke koje žive u sjeni. Izlaganje biljaka visokom intenzitetu svjetlosti dovelo je do smanjenja vrijednosti optimalnog prinosa i stope prijenosa elektrona, a porasla je vrijednost nefotokemijskog gašenja. Tijekom izlaganja visokom intenzitetu svjetlosti u biljkama je izmjeren niži udio klorofila u tkivu te povećan udio karotenoida, a povećali su se i udjeli fenola, tanina, flavonoida i antocijana. Ovi rezultati ukazuju da je izlaganje visokom intenzitetu svjetlosti dovelo do preopterećenosti fotosintetskog aparata i fotoinhibicije. Međutim došlo je i do prilagođavanja biljaka jer je za očekivati da će se zbog manjeg udjela klorofila smanjiti apsorpcija energije, odnosno povišenjem udjela karotenoida povećat oslobađanje viška energije u obliku topline što će zaštiti fotosintetski aparat od svjetlosnog stresa. Osim toga, uočeno povećanje udjela fenolnih spojeva u tkivu također može imati ulogu u zaštiti biljaka od oksidacijskog stresa uzrokovanog svjetlosnim stresom i/ili u smanjenju apsorpcije svjetlosne energije.

Abstract (english)

Roundleaf sundew (Drosera rotundifolia L.) is a carnivorous plant that inhabits peat-bog areas which are rare in Croatia and in danger of extinction. Proposed mowing treatment of high vegetation prevents the disappearance of peat-bogs due to overgrowth, but also exposes shade-acclimated plants to high light conditions. The aim of this study was to determine the changes in photosynthethic efficiency well as content of photosynthetic pigments and phenolic compounds in shade-acclimated plants exposed to high light intensity radiation (700 ± 20 μmol photons m-2 s-1) for 5, 30, 50 and 100 h. Plants exposed to 5 and 100 h of high-light radiation were brought to the 7 days recovery under low light intensity. The control group of plants were grown under low intensity radiation (40 ± 20 μmol photons m-2 s-1) and represented shade-acclimated plants. The sudden exposure of shade-acclimated plants to high light intensity decreased the fluorescence-based maximal quantum yield of PSII and rate of electron transfer, but increased the value of non-photochemical quenching. Following high light exposure the plants have reduced the chlorophyll content in tissue, but increased carotenoids content as well as content of total phenols, tannins, flavonoids and anthocyanins. These results suggest that the exposure to high light intensity led to an overload of the photosynthetic apparatus and photoinhibition. However, acclimatization of plants was also observed because it is expected that the lower chlorophyll content would result in reduced energy absorption while increased carotenoids could dissipate excess energy thus protecting photosynthetic apparatus from excess light. In addition observed increase of phenolic compounds would protect plants from oxidative stress and/or further reduce the absorption of excess light energy.

• Keywords: svjetlosni stres; fluorescencija klorofila a; fotosintetski pigmenti; fenolni spojevi; reaktivni kisikovi spojevi; rosika
• Keywords (english): light stress; fluorescence of chlorophyll a; photosynthetic pigments; phenolic compounds; reactive oxygen species; sundew
• Language: croatian
• URN:NBN: urn:nbn:hr:217:951730
• Study programme: Title: Integrated undergraduate and graduate university study of Biology and Chemistry Education; specializations in: Integrated undergraduate and graduate university study of Biology and Chemistry Education; Course: Integrated undergraduate and graduate university study of Biology and Chemistry Education; Study programme type: university; Study level: integrated undergraduate and graduate; Academic / professional title: magistar/magistra edukacije biologije i kemije (magistar/magistra edukacije biologije i kemije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2017-04-24 11:45:43