|
|
Role of brassinosteroids in plant response to drought stress
Trubanová, Nina ; Rothová, Olga (advisor) ; Urban, Milan (referee)
Brassinosteroids are steroid phytohormones with a wide range of effects. They improve survivance of plants exposed to drought stress, increase their resistence and yield therethrough. They regulate the response of plants directly (via synthesis of metabolits) and/or indirectly (via the induction of antioxidant compounds and enzymes), often in interaction with other phytohormones. Experiments studying influence of brassinosteroids on response of plants stressed with water deficit differ in several parameters. Their correct interpretation is complicated conseguently.
|
|
|
Response of different genotypes of Zea mays L. and Vicia faba L. treated with brassinosteroids to water deficit
Kuklíková, Radka ; Rothová, Olga (advisor) ; Hnilička, František (referee)
This work monitors the response of plants to the application of a solution of synthetic brassinosteroid (5-fluor-3α,17β-dihydroxy-5α-pregnan-6-on) under drought stress conditions and subsequent restoration of water availability. The response of two plant species was monitored under six-day period of cessation of watering and under six-day period of renewed optimal water supply. The experiments were carried out on plants with different type of photosynthesis - C3 plant Vicia faba L. and C4 plant Zea mays L.. For both plant species, three varieties/genotypes were used. Photosynthetic, morphological and developmental characteristics were monitored. The brassinosteroid treatment influenced more the morphological than the photosynthetic characteristics. The content of photosynthetic pigments was influenced more than the chlorophyll fluorescence parameters. The differences in morphological characteristics between individual varieties/genotypes were observed. The response to the application of brassinosteroid was observed especially for drought-sensitive variety/genotype. Application of brassinosteroid caused increase of the dry mass of leaves and roots, the height to leaf , the height of the whole plant and its increment under stress and post-stress periods in both plant species. The content of...
|
|
|
Potential of brassinosteroids for forest seed management with regard to species utilizable as Christmas trees
Jílek, Jan ; Kuneš, Ivan (advisor) ; Olga, Olga (referee)
The aim of this work is to assess the effect of brassinosteroids on germination of selected forest tree species with a potential to be used for the production of Christmas trees.The synthetically prepared analog 24-epibrassinolide (was tested on germination of seeds of Scots pine (Pinus sylvestris L.). Prior to launch of germination, the seeds were being soaked for 48 hours at three different concentrations of the tested brassinosteroid (BR-treatments) and in distilled water only (control), respectively. Seeds of each above-mentioned treatment were exposed to two alternative regimes: the stressed and unstressed one, respectively. In the stressed regime, seeds were exposed to a stress episode with temperatures up to 42 °C. In the unstressed regime the temperatures followed a pattern prescribed by Czech seed testing rules. Fully germinated seeds (the length of root radicle at least 4 times longer than the size of seed) were calculated. The root radicle length of each germinated seed was measured as well.The best results were recorded in the BR-treatment with the highest concentration of the tested brassinosteroid (0.4 mg.dm-3) in both germination regimes.
As contrasted to the control, the high concentration treatment increased germination capacity in the unstressed and stressed regime by 16.8% and 31%, respectively.
|
|
|
@Potential of brassinosteroids for forest seed and nursery management and for forest regeneration@
Bach, Petr ; Kuneš, Ivan (advisor) ; Švec, Otakar (referee)
Brassinosteroids (BRs) are a class of polyhydroxysteroids that have been recognized as a sixth class of plant hormones. In specific conditions BRs can positively influence the plant growth and development. The first isolated brassinosteroid was natural Brassinolide from rapeseed (Brassica napus L.). Recently BRs are extracted primarily synthetically; they are effective even in very low concentrations. Several studies of different plant species show positive influence of BRs on growth, flowering, germination and resistance to stress factors. Existing scientific studies that deal with BRs impact on plants were predominantly applied on agricultural crops. Until presence, the similar research in forest seed treatment and forest nursery was almost missing. In the Czech Republic the Department of Silviculture of the Faculty of Forestry and Wood Sciences of the Czech University of Life Sciences Prague newly started to deal with the use of BRs in forestry. The aim of this master thesis is to elaborate literature review on BRs and to summarize existing research of their impact on plants. Second part of the thesis solves influence of BRs on Scots pine (Pinus silvestris) seeds germination. Tests are performed in normal and in stress conditions. Results of the practical part show that BRs affect positively seed germination in normal conditions; seeds treated with BRs show higher germination rate than control seeds. Positive impact was not registered when the seeds were exposed to stress factor -- heat. Any research paper showing significant positive influence on forest seedlings in Central European conditions was not published yet.
|
|
|
Fytoestrogeny v potravinářství
Došková, Markéta
Phytoestroegens are biologically active compounds naturally occuring in plant materials. This group consists mainly of polyphenols characterized by structural similarities with female hormone 17-beta-estradiol. Plants produce phytoestrogens as their secundary metabolities, primarily due to the reaction as a response to various stress. Agents with estrogen effect contained in foodstuffs bring very positive impact on our health. On the other hand, some of the estrogen compounds may be harmful to the health depending on the concentration and the complex state of the consumer, as well as mycoestrogens, xenoestrogens and antiestrogens. Also for this reason is necessary to detect and quantify them in the sample of food. The major problem encountered in the studies of their effect is large amount of a variety of other substances in biological material, and according to their complicated structure was important to establish a reliable method, that was used also in the practical part of my experiment. It is an UPLC-MS/MS -- combination of Ultra High Performance Liquid Chromatography and Tandem Mass Spectrometry preceded by complex sample preparation which involves also SPE purification ("solid phase extraction").
|
|
| |
|
| |
guest ::
