Browsing by Subject "Plant Production Science (Plant Breeding)"

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  • Hautsalo, Juho (Helsingfors universitet, 2013)
    The objective of this study was to develop functional method for producing doupled-haploid plants for faba bean. Microspore culture is an advanced method to produce doubled-haploids and it is based on the totipotent nature of plant cells, since even a microspore, which is an immature pollen cell with haploid genome, can develop into a plant. This plant is either haploid or doupled haploid depending on whether there has been chromosome doubling or not and because the chromosomes either do not have pairs or the pairs are pure copies of each other, the plant is completely homozygous. Doubled haploids are already used in breeding programs with several crops such as wheat, barley and oilseed rape. Faba bean is an important legume for food, feed and crop rotation. Together with other legumes it has the potential to replace soybean imports entirely in Finland. Faba bean yield stability and anti-nutritional factors restrain its use and active breeding is required to improve the crop. In Finland, where pea and faba bean are the only grain legumes actively cultivated, the breeding of faba bean has been recently reactivated and its objectives are earliness, higher yield, protein content and improved quality factors. Big bottle neck in faba bean breeding is the creation of pure homozygote lines because the partial cross-breeding in the species sets restrains for the procedure. In this study promising pea and chick pea protocols that were developed in 2009 and an efficient rapeseed protocol were applied with faba bean. The interaction of various stress treatments and two different induction media with five genotypes of faba bean on microspore culture were analysed. Pro-embryos and cell divisions were observed from the cultures. Heat shock was the most effective stress treatment. Effects of density and induction medium were high and cultivar’s low tannin content seemed to impact positively to induction efficiency. These results suggest that for faba bean microspore culture is as suitable method as anther culture is and that there is hope to produce doubled-haploid faba beans in the future.
  • Zhao, Yafei (Helsingfors universitet, 2013)
    The transition from vegetative growth to flower formation is especially crucial for the reproduction of flowering plants. This transition is controlled through the regulatory activities of a group of genes named as floral meristem identity genes, of which LEAFY (LFY) is thought as the most important one. As a plant-specific transcription factor, LFY controls flower formation and floral patterning, which has been most intensively studied in the model annual plant Arabidopsis. In contrast to the plant architecture and flower morphology in Arabidopsis, Gerbera (Gerbera hybrida), belonging to the large sunflower family (Asteraceae), processes head-like inflorescences with different types of flowers distinct in floral morphs, sex and sometimes coloration. Within the last decades, a number of MADS-box and TCP transcription factor genes have been functionally characterized using stable transgenic plants. Recently, another functional assessment method using virus-induced gene silencing (VIGS) has been developed in Gerbera hybrida. In this study, the expression pattern of GhLFY was analyzed in wild-type Gerbera and TRV-based GhLFY silencing was conducted in two Gerbera cultivars – Terra Regina and Grizzly. It could be concluded that the activity of GhLFY is involved in regulating flower development. In VIGS:GhLFY lines, leaf-like organs emerged in disc flowers and the identity of stamen and carpel was interrupted. However, further VIGS trials are needed verify the observed phenotypes. At the same time, two potential lfy mutants – Pingpong and Marimbo were analyzed in both phenotype and genotype. These cultivars show phenotypic alteration in inflorescence development and floral organ structures that were distinct from WT Gerbera. Although the expression level of GhLFY did not change among these cultivars, but the GhLFY sequences contained amino acids mutation sites and four missing proline amino acids in Marimbo were detected. The role of these mutation sites need to be further analyzed in later experimental steps.
  • Nguyen, Cuong Xuan (Helsingfors universitet, 2012)
    Phytoene desaturase (PDS) plays a key role in the carotenoid biosynthesis in plants. Knocked-down the expression of PDS gene by virus induced gene silencing (VIGS) shows the photobleached phenotype in infected plants so that it has been used as a marker or a long time in VIGS systems with range of plant species. Tobacco rattle virus (TRV) based VIGS system, which uses PDS as the visual marker has been successfully applied and showed the white phenotype in Gerbera hybrida. However, 2-pyrone synthase (PS) gene, which encodes the first enzyme in gerebrin/parasorboside biosynthesis, is significantly reduced in these infected VIGS albino sectors. The transcription level of 2PS gene was also strongly suppressed in leaves treated with photobleaching herbicide, Norflurazon (NF), which inhibits the activity of PDS. Thus, down-regulation of 2PS gene in photobleaching sectors is caused by silencing PDS gene rather than by reacting of gerbera to TRV in VIGS treatment. Interestingly, expression of 2PS in transgenic tobacco (Nicotina tabacum SR1) causes photooxidative bleaching of the leaves. The reduction of ??-carotene in white leaves which analyzed by thin layer chromatograph (TLC) is the main reason; however, the interference between gerberin/parasorboside and carotenoid biosynthesis in these transgenic plants is still unclear. To overcome the effect of overexpression 2PS gene, exogenous mevalonic acid lactone (MAL) could be applied to partially rescue this transgenic phenotype at the seedling stages.
  • Marton, Ana-Maria (Helsingfors universitet, 2011)
    Biological invasions affect biodiversity worldwide, and, consequently, the invaded ecosystems may suffer from significant losses in economic and cultural values. Impatiens glandulifera Royle (Balsaminaceae) is an invasive annual herb, native to the western Himalayas and introduced into Europe in the 19th century as a garden ornamental plant. The massive invasion of I. glandulifera is due to its high reproductive output, rapid growth and its ability to outcompete native species. In Finland, the first observations regarding the presence of I. glandulifera date from the year 1947, and today it is considered a serious problem in riparian habitats. The aim of this master’s thesis research is to reveal the population genetic structure of I. glandulifera in Finland and to find out whether there have been one or multiple invasions in Finland. The study focuses on investigating the origin of I. glandulifera in Southern Finland, by comparing plant samples from the Helsinki region with those from its native region and other regions of invasion. Samples from four populations in Helsinki and from the United Kingdom, Canada, India and Pakistan were collected and genotyped using 11 microsatellite markers. The genetic analyses were evaluated using the programs Arlequin and Structure. The results of the genetic analyses suggested that I. glandulifera has been introduced to Finland more than once. Multiple introductions are supported by the higher level of genetic diversity detected within and among Finnish populations than would be expected for a single introduction. Results of the Bayesian Structure analysis divided the four Finnish populations into four clusters. This geographical structure was further supported by pairwise Fst values among populations. The causes and potential consequences of such multiple introductions of I. glandulifera in Finland and further perspectives are discussed.