Trehalose (& / #945 / -D-glucopyranosyl-1,1-& / #945 / -D-glucopyranoside) is a non reducing
disaccharide of glucose that occurs in a large variety of organisms, ranging from bacteria to invertebrate animals, where it serves as an energy source or stress protectant. Until recently, only few plant species, mainly desiccation tolerant & / #8216 / resurrection& / #8217 / plants, were
considered to synthesize trehalose. Although most plant species do not appear to accumulate easily detectable amounts of trehalose, the discovery of genes for trehalose biosynthesis in Arabidopsis and in a range of crop plants suggests that the ability to
synthesize trehalose is widely distributed in the plant kingdom. In this study, three wheat cultivars (Triticum aestivum L.) Tosun, Bolal (stress tolerant) and Ç / akmak (stress
sensitive) were analysed for the presence of trehalose. Using gas chromatography-mass
spectrometry (GC-MS) analysis, trehalose was unambiguously identified in extracts from seeds and seedlings of three different wheat cultivars (Bolal, Tosun and Ç / akmak). The trehalose amount was quantified by high performance liquid chromatography
connected with refractory index detector. Effects of drought and salt stress on trehalose contents of wheat cultivars were studied at seedling level and trehalose analysis was achieved both on shoot and root tissues. It was found that trehalose had accumulated under salt and drought stress conditions in all wheat cultivars. The highest trehalose
accumulation was detected in roots of Bolal cultivar under drought stress condition.
Furthermore, trehalose metabolizing enzymes / trehalose-6-phosphate synthase (TPS)
and trehalase enzyme activities were measured in roots and shoots of Bolal and Ç / akmak cultivars under control, salt and drought stress conditions. The most interesting results that we found that TPS activity sharply increased under stress conditions. The activity of
TPS in roots under drought stress condition was the highest and reached to 3-4 times of its activity under control condition. The increase in the activity of TPS showed parallelism with trehalose accumulation under stress condition. Trehalase activity in Bolal cultivar decreased under both salt and drought stress conditions, however there
was no significant change in trehalase activity of Ç / akmak variety.
| Identifer | oai:union.ndltd.org:METU/oai:etd.lib.metu.edu.tr:http://etd.lib.metu.edu.tr/upload/3/1102482/index.pdf |
| Date | 01 January 2003 |
| Creators | Tarek, El-bashiti |
| Contributors | Yucel, Meral |
| Publisher | METU |
| Source Sets | Middle East Technical Univ. |
| Language | English |
| Detected Language | English |
| Type | Ph.D. Thesis |
| Format | text/pdf |
| Rights | To liberate the content for public access |
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