Pokazatelji starenja u listovima duhana (Nicotiana tabacum L.)

master's thesis

• Title (english): Indicators of senescence in tobacco leaves (Nicotiana tabacum L.)
• Author: Melita Matan
• Mentor: Branka Pevalek-Kozlina (mentor)
• Granter: University of Zagreb; Faculty of Science; (Department of Biology); Zagreb
• Defense date and country: 2008, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Biology

Abstract

Duhan se često koristi kao modelna biljka budući je razmjerno tolerantan i široko rasprostranjen. Proces starenja obično izaziva smanjenje fotosinteze te oksidacijski stres. Istraživala sam proces prirodnog starenja u listovima starosti 14, 30, 120 i 270 dana te proces prijevremenog starenja potaknut vodikovim peroksidom (10 mM) u listovima starim 14 dana. U ovom radu praćeni su djelotvornost fotosintetskog aparata (stvaranje i utrošak kisika, sadržaji klorofila i karotenoida), strukturne promjene u stanicama lista, pokazatelji oksidacijskog stresa (sadržaji vodikovog peroksida, malondialdehida i karbonilnih grupa te oštećenje DNA) i aktivnost antioksidacijskih enzima. U svim listovima duhana došlo je do povećanog utroška kisika i smanjenja sadržaja klorofila i karotenoida sa starošću listova kao i u listovima tretiranim vodikovim peroksidom. Poludebeli prerezi listova pokazali su smanjenje kloroplasta sa starošću listova te povećanje broja plastoglobula. Pregledom ultratankih prereza listova uočen je dobro razvijen tilakoidni sustav u svim listovima osim u onima od 14 dana te povećanje plastoglobula sa starošću listova i prisutnost škrobnih zrnaca. Starenjem listova uočeni su porast vodikova peroksida, sadržaja malondialdehida i karbonila dok je u listovima tretiranim vodikovim peroksidom došlo do smanjenja sadržaja vodikovog peroksida te povećanja sadržaja malondialdehida i karbonila. Analiza jezgara stanica komet testom nije pokazala znatno oštećenje molekule DNA. Aktivnost superoksid dismutaze se povećala, a aktivnosti katalaze i peroksidaza smanjila sa starošću listova. U tretiranim listovima aktivnosti antioksidacijskih enzima su se povećale. Rezultati ovog istraživanja ukazuju na sposobnost učinkovite obrane ove biljne vrste od oštećenja uzrokovanog oksidacijskim stresom te na ulogu vodikovog peroksida kao signalne molekule.

Abstract (english)

Tobacco is often used as model plant because it is widely distributed and considered to be moderately tolerant plant species. The process of senescence is characterized by decline in photosynthesis and induction of oxidative stress. We have investigated the process of natural senescence in leaves old 14, 30, 120 and 270 days and process of artificial senescence induced by 10 mM hydrogen peroxide in leaves old 14 days. The efficiency of photosynthetic system (oxygen evolution and consumption, chlorophyll and carotenoid contents) structural changes in leaf cells, indicators of oxidative stress (contents of hydrogen peroxide, malondialdehyde and carbonyl groups as well as DNA damage) and activities of antioxidative enzymes were monitored. Chlorophylls and carotenoid contents declined while oxygen consumption increased as a result of both natural and artificially induced senescence. Number of chloroplasts decreased while that of plastoglobuls increased with senescence as evident by light microscopy. Ultrathin slices showed well developed thylakoids in all samples and increase of size and number of starch grains as well as plastoglobuls with senescence. Carbonyl and MDA contents increased with natural and artificial senescence while hydrogen peroxide showed increase and decrease with natural and artificial senescence, respectively. DNA damage evaluated by Comet test was not observed in senescent tobacco leaves. Superoxide dismutase activity increased while catalase and peroxidase activities decreased in senescent tobacco leaves. Senescence induced by hydrogen peroxide activities of all antioxidative enzymes increased. Presented results show the efficiency of antioxidative enzymes to fight oxidative stress and show the importance of hydrogen peroxide as a signal molecule.

• Keywords: starenje; Nicotiana tabacum L.; oksidacijski stres; antioksidacijski enzimi; oštećenje DNA; strukturne promjene
• Keywords (english): senescence; Nicotiana tabacum L.; oxidative stress; antioxidative enzymes; degradation of DNA; struktural changes
• Language: croatian
• URN:NBN: urn:nbn:hr:217:711746
• 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: 2018-03-05 12:19:48