Molecular characterization and expression profiling of cd-responsive genes in triticum durum
Cebeci, Özge (2006) Molecular characterization and expression profiling of cd-responsive genes in triticum durum. [Thesis]
Cadmium (Cd) is a toxic heavy metal which has detrimental effects both in plants and human. There is a lack of knowledge on the molecular mechanisms of Cd toxicity in crop plants. The objective of this study was to identify and clone expressed Cd-responsive genes from two Triticum durum cvs. Balcah-85 and Balcah-2000 using mRNA differential display technique. We identified 10 cDNA clones whose level of expression significantly changed upon Cd exposure and thus isolated for further characterization. Differential expression patterns of cDNA clones were verified by Northern blot and Real-Time PCR analyses. Analysis of putative protein sequences of these clones revealed that B02 encodes an HCBT-hke defense response protein, and B04 encodes NADH dehydrogenase, which is known to be involved in stress mechanism in plant systems. Four of these cDNA clones, B05, B06, B08, and BO10, showed significant homology to the receptor kinase proteins. Identification of receptor kinase proteins to an abiotic stress factor, Cd stress, is noted to be the first in literature. One of the cDNA clones, BOH, found to have significant homology to PsaC gene, encoding a photosysteml 8 kDa subunit. This result is in well agreement with the previous physiological studies indicating that Cd has detrimental effects on photosysteml and II in plants. The cDNA clones B03, B07, and B09 found to be novel sequences for which sequence comparison showed no homology in GenBank. These results suggest that Cd has various effects on gene expression and alters expression of different genes. Our findings also demonstrate that mRNA differential display technique is useful to understand molecular mechanisms affected by Cd.
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