|
|
Regulation of floral initiation in woody perennials
Čermák, Vladimír ; Mašková, Petra (advisor) ; Čermák, Vojtěch (referee)
Floral initiation is an important process for temperate woody perennials that affects the subsequent development of the flower. Although this process is well known in annual plants such as Arabidopsis thaliana, not much research has been done in woody plants. This review summarizes the knowledge about mechanisms of flowering induction in woody perennials, compared to the findings in model plants, especially A. thaliana, including factors involved in the regulation of the flowering process. In particular, FT-like genes and TFL1-like genes, which play an important role in the regulation of flowering induction, are discussed in detail. In temperate woody plants the dormancy period follows the floral induction before the floral development. Periodic regulation of this stage is controlled endogenously and, in addition to other factors, it is affected by expression of DAM genes. The genetic mechanisms regulating endodormancy release in woody perennials are similar to vernalization in herbs. Better understanding of processes such as the floral induction and endodormancy release can help us to develop cultivars with a modified flowering time.
|
|
|
Role cytokininů při teplotou indukovaném přechodu rostlin z vegetativní do generativní fáze
Malých, Veronika
Recent numerous studies have been focused on the impact of the climate changes on the crop production. The response of plants to increased temperature include hypocotyl and petiole elongation, leaf hyponasty, alternations in timing of the flowering and even the inhibition of the flower bud development which may lead to reduced crop yields. Acclimation and stress responses are co-regulated by levels of plant phytohormones such as auxins, gibberellins, brassinosteroids and cytokinins. Although cytokinins play important role in physiological and developmental processes the effect of the interplay of temperature and cytokinin in growth and developmental processes has not been studied till now. This thesis is focused on the impact of cytokinins on thermomorphology and time of flowering of Arabidopsis thaliana in combination with increased temperature under long day conditions. It was observed that modulation of cytokinin levels reduce biomass and area of leaf rosette and this effect is dependent on temperature. As next, it was confirmed that interactions of cytokinins and temperature play important role in transition to generative developmental stage of plant Arabidopsis.
|
|
|
Plant meteoreception
Kampová, Anna ; Vosolsobě, Stanislav (advisor) ; Kulich, Ivan (referee)
Flowering is a crucial event in a life cycle of every single plant. Various plant species are differently affected by weather in this time of their life cycle. Weather may have an impact on flower opening speed and timing and also on flower longevity. Timing of flower opening is very important. If flower opening takes place when weather conditions are unsuited, it can be for such plant terminal, or more precisely terminal for its ability to reproduce. Flower can be very important for male fitness protection. Flower opening is regulated by phytohormones and some other signal pathways - pathways of vernalization, gibberellins, photoperiod and an autonomous one which is independent from photoperiod. Phytohormones and regulation pathways mentioned above may respond to exogenous factors, namely temperature, light, air humidity and rain. Furthermore, an anther dehiscence is the key stage of flowering. Its timing and process have a huge effect on success of plant reproduction. It is also controlled by changing of weather conditions and by phytohormones, jasmonic acid is the main trigger of this process. Environmental factors influence on anther dehiscence was not examined in detail. Key words: flower opening, anther dehiscence, environmental factors
|
|
|
Regulation of floral initiation in woody perennials
Čermák, Vladimír ; Mašková, Petra (advisor) ; Čermák, Vojtěch (referee)
Floral initiation is an important process for temperate woody perennials that affects the subsequent development of the flower. Although this process is well known in annual plants such as Arabidopsis thaliana, not much research has been done in woody plants. This review summarizes the knowledge about mechanisms of flowering induction in woody perennials, compared to the findings in model plants, especially A. thaliana, including factors involved in the regulation of the flowering process. In particular, FT-like genes and TFL1-like genes, which play an important role in the regulation of flowering induction, are discussed in detail. In temperate woody plants the dormancy period follows the floral induction before the floral development. Periodic regulation of this stage is controlled endogenously and, in addition to other factors, it is affected by expression of DAM genes. The genetic mechanisms regulating endodormancy release in woody perennials are similar to vernalization in herbs. Better understanding of processes such as the floral induction and endodormancy release can help us to develop cultivars with a modified flowering time.
|
|
|
The role of small non-coding RNAs in the regulation of plant reproductive development
Hromadová, Michaela ; Honys, David (advisor) ; Rothová, Olga (referee)
Small RNAs (sRNA) are broadly defined as regulatory molecules of 21-24 nucleotides in length which belong to the class of noncoding RNAs. They usually originate in response to the presence of double-stranded RNA in the cells and facilitate transcriptional and posttranscriptional gene silencing of complementary sequences. Their role lies not only in defence against exogenous nucleic acids, but primarily in the regulation of endogenous genes. Typical target molecules of plant sRNA are transposable elements and genes encoding the transcription factors involved in the control of key developmental transitions like the initiation of the reproductive phase and the regulation of its progress. The aim of this thesis is a summary of functional roles of individual small RNA in plant reproductive development, with focus to the female and male gametophytes and in the protection against the transition of transposable elements to following generations. Both endogenous and exogenous sRNA are amply utilized in plants, because they provide an immediate and direct response of the organism to rapidly changing conditions, and thus undoubtedly belong to the key factors which contribute to their phenotypic plasticity.
|
|
|
Hodnocení kvetení vabraných druhů kosatců skupiny Limniris
Závišková, Lenka
Bachelor thesis go about description genus Iris and each groups, evaluation of cultivars Iris sibirica. From school lands Faculty of Horticulture in Lednice were evaluated fifteen cultivars. Based on self-evaluation and measurement it was created convenient descriptor, which contain seven characters. The best from evaluated was Iris sibirica 'Dance Ballerina Dance', Iris sibirica 'Fourford White', Iris sibirica 'Marantha', Iris sibirica 'Sea Shadows', Iris sibirica 'White Swirl', Iris sibirica 'Zweiters Hundred', this cultivars had the most blossoms. From aesthetic aspects it was Iris sibirica 'Fourfold White', which has the biggest blossom and the widest blossom has cultivar Iris sibirica 'Zweiters Hundred'. The best cultivar from garden aspect it was Iris sibirica 'Strandperle', which was the highest from all cultivars. All reviews cultivars weren't susceptible to attack by pathogens and pests apart from Iris sibirica 'Fourfold White' from which was found presence of Aphis fabae and Iris sibirica 'White Horses' was found Mononychus punctumalbum.
|
|
|
The infuence of known regulatory factors on the population dynamics of selected orchid species on the orchid meadow (Peklo locality)
ČEPA, Luboš
Populations of strongly endangered species Orchis mascula and endangered Dactylorhiza majalis were monitored at Peklo area since 2000. In May 2002, another strongly endangered orchid species Orchis ustulata was discovered. The major increase in counts of O. ustulata towards stable numbers of O. mascula and D. majalis populations was detected during the seven year period of plant monitoring. The aim of this study was to reveal a connection between the climate conditions and orchid vitality, using biometrical plant data gained between 2005 to 2011. In order to evaluate a steady state of investigated area, the extensive phytocoenological sampling was conducted. The obtained data revealed several different loci at the screened grassland, which can be defined with presence of distinctive species. In blooming individuals of O. mascula, March temperature was the most defining factor. Parameters studied (number of leaves and blossoms, size of leaves, lenght of stems and duration of flowering) increased with decreasing March temperature. The blooming proved to be important factor, if a plant was in flower that year or the preceeding year, the number and the size of leaves was larger. The blooming in two subsequent years enhanced this described effect even more. The comparison of blooming individuals of O. ustulata revealed that plants growing in clusters were non flowering but bigger in size. Other positive correlation with investigated parameters had precipitation in December. However, the comparison of all plants showed generally smaller size of cluster forming plants. This overall analysis pointed out the influence of low temperature in October, the plants were smaller in size and amount of sterile individuals rised. All collected data and generated comparisons support earlier findings about influence of temperature and precipitation on the orchid population dynamics.
|
|
|
Use of image analysis in the monitoring of critically endangered species Spiranthes spiralis
IPSER, Zdeněk
A population of an endangered orchid species Spiranthes spiralis was discovered in 1980 in the National natural monument Pastviště u Fínů in village Albrechtice, near Sušice. Since 1985 the number of flowering individuals of this population has been regularly monitored. Since autumn 1998 all the specimen found there have been marked and biometrically measured. Since the beginning of monitoring, big fluctuations in the number of flowering specimens or in survival of the individual plant rosettes have been observed among the years. The aim of this thesis was to design the so called index of shading and to verify the possibility of its use to explain some phenomena of plant population dynamics. The index was designed with image analysis and biometric data. The hypothesis has been tested, that the basic variable determining the plant{\crq}s fitness (survival, flowering, vegetative propagation etc.) is the rate of shading by neighboring vegetation (expressed with the index of shading). It has been found that the effect of shading on flowering is not significant or hidden by other factors (such as the course of the weather in the season etc.). The size of the leaf area affects the probability of flowering, number of blooms and height of the inflorescence stem. My thesis also focused on costs of flowering, survival probability (since 1998) and flowering dynamics (since 1986).
|
guest ::
