Odgovor biljaka na toplotni stres

undergraduate thesis

• Title (english): Heat stress response in plants
• Author: Maja Ivošević
• Mentor: Željka Vidaković Cifrek (mentor)
• Granter: University of Zagreb; Faculty of Science; (Department of Biology); Zagreb
• Defense date and country: 2016, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Biology

Abstract

Toplotni stres djeluje na sve procese u biljci, kao što su klijanje, rast, razvoj, reprodukcija, starenje, fotosinteza i disanje. Na molekularnoj razini uzrokuje destabilizaciju membrana, denaturaciju proteina i drugih makromolekula te nastajanje povećane količine ROS koji uzrokuju oštećenja svih dijelova stanice i bitnih makromolekula. Toplinom uzrokovana destabilizacija tilakoidnih membrana i modifikacija aktivnosti enzima Rubisco djeluju na proces fotosinteze. C4 i CAM biljke su uspješnije u suočavanju s toplotnim stresom jer imaju mehanizme kojima umanjuju oksigenaznu aktivnost Rubisca. Prilagodba biljaka na toplotni stres obuhvaća dva mehanizma: izbjegavanje i toleranciju. Primjeri mehanizma izbjegavanja su npr. mijenjanje položaja listova u odnosu na smjer Sunčevog zračenja i odvijanje reproduktivnog dijela životnog ciklusa u hladnijem dijelu godine. Mehanizam tolerancije uključuje mnogo širu paletu strategija - proizvodnju proteina toplotnog stresa (HSP) i antioksidansa kao najvažnijih, zatim kompatibilnih osmolita, hormona i sekundarnih metabolita. Osim HSP i neki drugi proteini sudjeluju u zaštiti stanice, npr. ubikvitin, dehidrini i proteini LEA. Antioksidansi sudjeluju u zaštiti od oksidacijskog stresa. Postoje enzimski (npr. katalaza, askorbat peroksidaza, superoksid dismutaza, peroksidaza i glutation reduktaza) i neenzimski antioksidansi (npr. askorbat, glutation, tokoferol i karoten), a uloga im je neutralizacija ROS. Od hormona najvažniji utjecaj na biljku u uvjetima toplotnog stresa imaju ABA i etilen.

Abstract (english)

Heat stress has an effect on all plant processes, for example seed germination, growth, development, reproduction, photosynthesis and respiration. On a molecular level, it causes membrane destabilisation, protein denaturation and the denaturation of other molecules, but also the creation of ROS which causes damage to all parts of the cell and to important macromolecules. Heat-caused destabilisation of thylakoid membranes and the modification of Rubisco activity affects photosynthesis. C4 and CAM plants are more successful in dealing with stress because they have mechanisms that reduce the oxygenation activity of Rubisco. Plant adaptation to heat stress includes two mechanisms: avoidance and tolerance. The avoidance mechanism protects the plant from heat stress and sun radiation, it is for example movement of leaves positions and completion of reproductive cycle in the colder part of the year. The tolerance mechanism includes a much wider approach. The most important strategies are the production of heat shock proteins (HSP) and antioxidants. Some other molecules are osmolytes, hormones and secondary metabolites. Besides HSP, there are other proteins that protect the cell: ubiquitin, dehydrins and LEA proteins. Antioxidants protect from oxidative stress. There are enzyme (catalase, ascorbate peroxidase, superoxide dismutase, peroxide and glutathione dismutase) and nonenzyme antioxidants (ascorbate, glutathione, tochopherol and carotene) and their role is ROS neutralisation. ABA and ethylene have the most important effects among the hormones.

• Keywords: toplotni stres; prilagodba biljaka
• Keywords (english): heat stress; plant adaption
• Language: croatian
• URN:NBN: urn:nbn:hr:217:609154
• Study programme: Title: Ecology; Study programme type: university; Study level: undergraduate; Academic / professional title: sveučilišni/a prvostupnik/prvostupnica (baccalaureus/baccalaurea) biologije (sveučilišni/a prvostupnik/prvostupnica (baccalaureus/baccalaurea) biologije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2018-01-02 11:10:53