Kadmium által indukált élettani változások kukoricában pál magda

7. ÖSSZEFOGLALÁS

• 
  Munkánk során kimutattuk, hogy az általunk beállított kísérleti körülmények között, a 10, 25 és 50 M-os kadmiumkezelésre a kukoricanövény levele és gyökere eltérő módon reagált. A levélben a kadmiumkezelés oxidatív stressz indukált, amit a vizsgált 3 stresszmarker értékeinek változása igazolt, míg a gyökérben nem volt kimutatható az oxidatív stressz tünete.
  
• 
  Vizsgálataink azt mutatták, hogy a 7 napos kadmiumkezelés során kukorica levelében a PG és PE, gyökerében az MGDG, PG, PE és DGDG lipidfrakciók zsírsav összetétele megváltozott. Megállapítottuk, hogy különösen az alacsonyabb (10 és 25 M) koncentrációjú kadmiumkezelést követően, a rövid szénatomszámú, telített zsírsavak mennyiségének csökkenésével nőtt a hosszabb szénatomszámú, telítetlen zsírsavak aránya, amit a DBI és a telítetlenségi százalék megemelkedése követett.
  
• 
  Bár a kadmiumkezelés nem befolyásolta számottevően a levél cisztein- és glutationtartalmát, de jelentősen megemelte a -glutamil-cisztein koncentrációját. A gyökérben a -glutamil-cisztein mennyisége szintén megemelkedett, de a GSH mennyisége drasztikusan csökkent.
  
• 
  A levélben a kadmium hatására a GR (4. napon) és a POD (7. napon) enzimek aktiválódtak, míg a gyökérben nem tapasztaltuk az antioxidáns enzimek indukcióját.
  
• 
  A kadmiumkezelés hatására a kukorica levelében az in vivo PC2 szint nem változott, de az in vitro PCS aktivitás megemelkedett. A kadmiummal kezelt növények gyökérében az in vivo PC2 szint megemelkedett, míg az in vitro PCS aktivitás csökkent a kontrollhoz képest. Megerősítettük, hogy a gyökérben a PCS enzim jelenléte konstans, a levélben pedig kadmium jelenléte szükséges szintézisének indukciójához.
  
• 
  Kimutattuk, hogy a kadmium 7 nap elteltével a levélben a SA felhalmozódás mellett, BA és o-HCA akkumulációt is indukált mind szabad, mind kötött formában, és a megemelkedett szalicilsav szintézis feltételezhetően benzoesavon keresztül történt. A gyökérben csak az 50 M-os kezelés volt hatással a szabad o-HCA és kötött BA szintjére.
  

8. SUMMARY

• 
  It was found that the leaves and roots of maize plants gave different responses to 10, 25 and 50 M cadmium treatments. While the cadmium induced oxidative stress in the leaves was confirmed by the changes in the value of the three stress markers examined, no such oxidative stress could be observed in the roots.
  
• 
  In leaves the fatty acid composition of PG and PE changed, whereas in the roots the fatty acid composition of MGDG, PG, PE and DGDG were modified during 7 days of cadmium treatment. It was established that the rate of unsaturated fatty acids with longer carbon chain increased by the reduction in the amount of saturated fatty acids with shorter carbon chain, which was followed by a rise in DBI and unsaturation rates, especially after cadmium treatments of lower concentrations (10 and 25 M).
  
• 
  Though cadmium treatment did not have a considerable effect on the cysteine and glutathione contents of the leaves, however, it significantly increased the concentration of -glutamyl-cysteine. In the roots, there was also a rise in the amount of -glutamyl-cysteine, but GSH content decreased drastically.
  
• 
  Due to the cadmium stress, GR and POD enzymes were activated in the leaves on day 4 and day 7, respectively. However, the induction of antioxidant enzymes could not be observed in the roots.
  
• 
  In the maize leaves, the in vivo PC2 level did not change as a result of cadmium treatment, but there was an increase in the in vitro PCS activity. In the roots of plants treated with cadmium, a rise in the in vivo PC2 level was detected, however, the in vitro PCS activity decreased as compared to that of the control. Our results verify that the presence of PCS enzyme is constant in the roots, while in the leaves the synthesis of PCS enzyme is induced by cadmium.
  
• 
  It was demonstrated that after 7 days of treatment, Cd increased the levels of free and bound forms of BA, o-HCA and SA in the leaves. The intermediate element of increased salicylic acid synthesis is supposed to be benzoic acid. In the roots, only the 50 µM rate of Cd caused changes in the free o-HCA acid and bound BA content.
  

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KÖSZÖNETNYILVÁNITÁS

Köszönet illeti az MTA Mezőgazdasági Kutatóintézete vezetőségét mindazért a támogatásért, amely lehetővé tette ezen munka elvégzését és a disszertáció elkészítését.

Köszönetemet fejezem ki témavezetőmnek, Dr. Szalai Gabriellának szakmai irányításáért, türelméért és bizalmáért.

Külön köszönettel tartozom Dr. Janda Tibornak, hogy tanácsaira és támogatására mindig számíthattam.

Megköszönöm közvetlen kollégáimnak, Dr. Páldi Emilnek, Dr. Horváth Eszternek, Kövesdi Ferencnének és Kóti Gyulánénak a kísérletek kivitelezése során nyújtott nélkülözhetetlen segítségüket és az általuk biztosított egyedien családias légkört.

Köszönettel tartozom a Fitotron munkatársainak a növénynevelés során nyújtott segítségükért.

Köszönetemet fejezem ki mindazoknak a kollégáknak, akik bármilyen formában segítették a munkámat.

Végül külön köszönet illeti családomat, szüleimet, hogy mindig mellettem álltak, támogattak szeretetükkel és gyermekeimet türelmükért.