فهرست مطالب بهناز دولت آبادی

Dehydrins (DNHs) belong to group II of LEA (Late Embryogenesis Abundant) protein family which are expressed in late embryogenesis and accumulate in vegetative tissues in response to multiple abiotic stresses such as salt, drought and cold stress These proteins could be classified to five subgroups (YnSKn, Kn, SKn, KnS, and YnKn) based on the sequence and number of K, S, and Y segments. In this study, 5 genes encoding dehydrin protein (DHN) were identified in Aeluropus littoralis, genome as a halophyte grass, belonging to the Poaceae family and physicochemical characteristics, cell localization, conserved motifs and gene structure were determined and evolutionary relationships among different species were considered. AlDHN proteins were classified in the YnSKn subgroup based on highly conserved domains. The expression pattern of AlDHN.5 gene as a homologue of RAB18 (AT5G66400) gene was examined in both leaf and root tissues under salinity, drought, cold stresses and abscisic acid treatment. Analysis of the expression pattern of this gene in both leaf and root tissues showed that this gene is more expressed in leaf tissue compared to root under drought, cold stresses and ABA treatment. Current study lays the foundation for further studies into the regulation of their expression under various environmental conditions.

Fusarium wilt caused by Fusarium oxysporum f.sp. Lycopersici is one of the major obstacles to the production of tomato which causes huge losses in tomato products worldwide. In order to increase the tolerance to this disease, a triple structure containing PR1, chitinase and glucanase genes controlled by 35S promoter was transferred to tomato. Eight days after planting on pre-culture medium, explants were inoculated by Agrobacterium tumefaciens strain LBA4404 containing the aforementioned plasmid. When the regenerated shoots grew to 2-3 cm, they were cut and transferred to rooting medium.The plantlets were then transferred to pots filled with a soil mixture of peat moss and perlite for further acclimatization. The putative transgenic plant lines were analyzed by multiplex PCR and the transcription of the transgenes was confirmed by RT-PCR method using the specific primers. The estimated value for the frequency of the simultaneous transfer of chitinase, glucanase and PR1 genes to tomato was 2.7%. Protein extracts of transgenic plants expressing chitinase, glucanase and PR1 genes inhibited in vitro hyphal growth of F. oxysporum f.sp. lycopersici. Compared with non-transgenic control plants, despite some alterations in chlorophyll content no other morphological changes were observed in transgenic plants. The total content of chlorophyll “a” and “b” in transgenic plants were 31.8 and 36.2 % higher than that of control plants, respectively, which may be attributed to metabolic changes due to simultaneous expression of three transgenes.

Tomato is one of the most important crops in the world which is vastly cultivated everywhere. This crop bears a great loss every year due to the presence of pathogenic fungi such as Fusarium species. In present study in order to strengthen defense mechanism of tomato, we transferred coincidently the genes PR1, chitinase and gluconase into tomato. To do so, first, the gene PR1 was extracted from tobacco genome and then replicated under the control of 35S promoter and Nos terminator in recombinant vector pBI121. In addition, chitinase and gluconase genes were replicated under the control of independent 35S promoter and Nos terminator in vicinity of PR1 gene. It is followed by transformation of tomato explants with PRP-1ChiGlu(-) containing PR1, chitinase and gluconase genes by using recombinant vector pBI121. In this transformation, leaf explants placed on the pre-media were inoculated by Agrobacterium tumefaciens LBA4404 containing aforementioned vector. These explants were transferred first to similar media and then to regeneration media and every seven days were subjected to subculture and after 4 weeks they were transferred to root generation media containing 200 ml/lit Cefotaxime and 25 mg/lit Kanamycin. Molecular analysis of PCR and dot blotting showed that transgenic plants had at least one copy of in question genes on their genome.