Szerző szerinti böngészés "Ahres, Mohamed"
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Tétel Korlátozottan hozzáférhető Molecular background of circadian clock-, light quality- and temperature dependent regulation of freezing tolerance in cerealsGierczik, Krisztián; Boldizsár, Ákos; Novák, Aliz; Ahres, Mohamed; Ádám, Éva; Kozma-Bognár, László; Vágújfalvi, Attila; PhD hallgató; egyetemi oktató, kutatóLow red to far-red (R/FR) ratio enhances freezing tolerance at 15°C in winter wheat and in winter barley genotypes (B-C) but not in winter einkorn wheat (A). Under the low R/FR ratio, the expression level of CBF14 gene is much higher in winter wheat and in winter barley (E-F) than in winter einkorn wheat (D). The expression of Phytochrome A (PHYA) increases in each genotype under low R/FR ratio (G-I), but the PHYB level increases only in winter einkorn wheat significantly (G-I).Tétel Korlátozottan hozzáférhető Overexpression of two upstream phospholipid signaling genes improves cold stress response and hypoxia tolerance, but leads to developmental abnormalities in barleyGierczik, Krisztián; Székely, András; Ahres, Mohamed; Marozsán-Tóth, Zsuzsanna; Vashegyi, Ildikó; Harwood, Wendy; Tóth, Balázs; Galiba, Gábor; Soltész, Alexandra; Vágújfalvi, Attila; PhD hallgató; egyetemi oktató, kutatóPhosphatidylinositol transfer protein (PITP) and phosphatidylinositol 4-kinase (PI4K) are very upstream regulatory elements of the phospholipid signaling pathway in the signal transduction network. Unlike in animal systems, their role in stress signaling is poorly understood in plants. To study this area, PITP- and PI4K-overexpressing transgenic barley lines were developed. Morphological and developmental abnormalities were surveyed and characterized. It was revealed that the overexpression of the upstream signaling genes led to more phenotypic abnormalities than in other transgenic studies working with effector genes or even transcription factors. We hypothesize that this high level of abnormalities is the consequence of the modulation of the very upstream signal transduction pathway elements. On the other hand, we also revealed that overexpression of the PITP and PI4K genes increased stress tolerance during hypoxic cold stress, but not during salinity stress. Differences were also found in the level of frost tolerance between the transgenic overexpression plants and the recipient Golden Promise line. Molecular analysis showed that this improvement was not related to the most important cold responsive transcription factors, the CBF genes. We conclude that the transgenic method may be useful to prove the role of an upstream signaling element; however, due to the many developmental consequences that occur as side effects, it is a less advisable approach to achieve improved stress tolerance.Tétel Korlátozottan hozzáférhető Role of light-intensity-dependent changes in thiol and amino acid metabolism in the adaptation of wheat to droughtGyugos, Mónika; Ahres, Mohamed; Gulyás, Zsolt; Szalai, Gabriella; Darkó, Éva; Végh, Balázs; Boldizsár, Ákos; Mednyánszky, Zsuzsa; Kumar Kar, Rup; Dey, Narottam; Simon-Sarkadi, Lívia; Galiba, Gábor; Kocsy, Gábor; PhD hallgató; egyetemi oktató, kutatóLight-intensity-dependent (low, normal and high) differences in thiol and amino acid metabolism during drought were compared in wheat seedlings. The drought-tolerant genotype (Plainsman) recovered better than the sensitive one (Cappelle Desprez) after the stress as shown by growth and photosynthetic parameters, the levels of which were greater in low and high light, respectively. Glutathione as an antioxidant contributed to this difference, since its level was twofold greater in Plainsman throughout the experiment. In addition, the accumulation of most amino acids even increased in normal light during drought in Plainsman, while such change occurred in Cappelle Desprez only in high light. The higher contents of proline, glutamate and γ-aminobutyrate are especially important because of their involvement in the protection against drought. The transcription of certain genes related to amino acid and glutathione metabolism and various antioxidants was even induced by higher light intensities before drought, which can contribute to the subsequent increase in the amount of the corresponding metabolites during stress. Increase in light intensity activated various protective mechanisms including greater accumulation of glutathione, proline and other amino acids during drought, which contributed to the efficient recovery of wheat after stress.Tétel Korlátozottan hozzáférhető Temperature and Light-Quality-Dependent Regulation of Freezing Tolerance in BarleyAhres, Mohamed; Gierczik, Krisztián; Boldizsár, Ákos; Vítámvás, Pavel; Galiba, Gábor; PhD hallgató; egyetemi oktató, kutatóIt is established that, besides the cold, incident light also has a crucial role in the cold acclimation process. To elucidate the interaction between these two external hardening factors, barley plantlets were grown under different light conditions with low, normal, and high light intensities at 5 and 15 ◦C. The expression of the HvCBF14 gene and two well-characterized members of the C-repeat binding factor (CBF)-regulon HvCOR14b and HvDHN5 were studied. In general, the expression level of the studied genes was several fold higher at 5 ◦C than that at 15 ◦C independently of the applied light intensity or the spectra. The complementary far-red (FR) illumination induced the expression of HvCBF14 and also its target gene HvCOR14b at both temperatures. However, this supplementation did not affect significantly the expression of HvDHN5. To test the physiological effects of these changes in environmental conditions, freezing tests were also performed. In all the cases, we found that the reduced R:FR ratio increased the frost tolerance of barley at every incident light intensity. These results show that the combined effects of cold, light intensity, and the modification of the R:FR light ratio can greatly influence the gene expression pattern of the plants, which can result in increased plant frost tolerance.