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Metali su prirodna sastavnica Zemljine kore, ali njihova koncentracija u okolišu se neprestano povećava uslijed antropogenih utjecaja. Teški metali mogu uzrokovati direktna i indirektna oštećenja važnih bioloških molekula, a njihova akumulacija u hranidbenom lancu predstavlja opasnost za sve organizme u okolišu. Cilj istraživanja bio je utvrditi učinak teških metala, kadmija i cinka te njihovih smjesa na stabilnost genoma klijanaca duhana Nicotiana tabacum L.. Cink i kadmij su kemijski vrlo slični teški metali pa kadmij može ometati vitalne, biološke reakcije u biljkama, zamjenjujući cink. Iako je pojedinačni utjecaj tih metala u biljnim organizmima detaljno istražen, njihovo međudjelovanje nije dovoljno poznato. U tu svrhu klijanci duhana su rasli mjesec dana na hranjivim podlogama uz dodatke različitih koncentracija metala i njihovih kombinacija. Razina oštećenja i promjene u molekuli DNA duhana nakon tretmana su procijenjeni metodom komet-testa i metodom nasumično umnožene polimorfne DNA (RAPD, engl. Random Amplified Polymorphic DNA). Iako su rezultati komet-testa pokazali oštećenje DNA djelovanjem teških metala kadmija i cinka na klijancima duhana, svakog zasebno i u kombinaciji, rezultati metode RAPD nisu pokazali promjenu u polimorfizmu DNA u niti jednom od tretmana. Komet-test se pokazao kao osjetljivija metoda pri detekciji oštećenja DNA nastalih teškim metalima za razliku od metode RAPD. Metals are natural components of the Earth’s crust but their concentration is constantly increasing due to anthropologic influences. Heavy metals can cause direct and indirect damages of vital biological molecules and their accumulation in the food chain is an immediate menace for all organisms in the environment. The objective of this research was to determine the effect of heavy metals, cadmium and zinc and their mixtures on the genome stability of tobacco seedlings. Even though the influences of these metals alone in plant organisms are researched in great detail, their interaction is not well known. Since zinc and cadmium are chemically very similar heavy metals, cadmium can interfere in vital, biological reactions inside the plants by replacing zinc. Seedlings were grown for 30 days on nutrient medium with addition of different metal concentrations and their mixtures. The extent of DNA damage and DNA alterations after the treatment were evaluated using the Comet assay and RAPD (Random Amplified Polymorphic DNA) method. Even though the results of Comet assay showed statistically significant DNA damage caused by heavy metals, individually and in mixtures, the results of RAPD analysis did not show any change in DNA polymorphism in all of the treatments. Comet assay proved to be a more sensitive method in detection of DNA damages caused by heavy metals in comparison to RAPD analysis.

Klimatske promjene jedan su od najvećih izazova s kojima se danas suočavamo. Biljke, kao sesilni organizmi, nemaju mogućnost regulacije temperature ponašanjem, stoga bi stresni uvjeti okoliša kao posljedica globalnog zatopljenja mogli biti katastrofalni za biljke. Cilj istraživanja bio je utvrditi učinak toplinskog stresa na stabilnost genoma duhana. Biljke različite starosti, jedan i tri mjeseca, su bile kratkotrajno (2 h i 4 h) izložene temperaturi od 42 °C i ostavljene na oporavku 3 dana. Razina oštećenja i promjene u molekuli DNA duhana neposredno nakon tretmana i kroz oporavak procijenjeni su primjenom molekularnih metoda komet-test i RAPD. Rezultati komet-testa su pokazali statistički značajna oštećenja DNA neposredno nakon 2 h i 4 h izlaganja povišenoj temperaturi u odnosu na kontrolni uzorak, te popravak oštećenja nakon 3 dana oporavka, bez obzira na starost biljke. Rezultati metode RAPD nisu pokazali razlike u DNA obrascima. Climate change is one of the biggest challenges we face today. Plants are sessile organisms, and as such do not have the ability to regulate their temperature by behavior. Therefore, stressful environmental conditions as a result of global warming may have catastrophic consequences for plants. The objective of this research was to determine the effect of heat stress on the genetic stability of tobacco plants. Plants of different ages, one and three months, were exposed short-term (2 h and 4 h) to temperature of 42 °C and left to recover for 3 days. The extent of DNA damage and DNA alterations after the treatment and during the recovery period were evaluated using the Comet assay and RAPD. Results of the Comet assay showed statistically significant damage to DNA immediately after 2 h and 4 h of exposure to high temperature compared to the control sample, but they also showed that damage was repaired after the 3 days of recovery, regardless of the plant age. RAPD analysis showed no difference in DNA profiles.