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Plant Phenotypes (plant + phenotype)
Selected AbstractsTrade-offs between the shade-avoidance response and plant resistance to herbivores?FUNCTIONAL ECOLOGY, Issue 6 2005Tests with mutant Cucumis sativus Summary 1Plants exhibit adaptations to many stresses, including light competition and herbivory. The expression of these traits may interact negatively, potentially instigating a trade-off. 2We employed a combination of genetically altered Cucumis sativus varieties and phenotypic manipulations to test for trade-offs in field experiments. The different genetic lines of C. sativus were altered in their phytochrome-mediated shade responses and the production of terpenoid defence compounds. 3Cucumber plants constitutively expressing the shade-avoidance response had 93% more herbivory by specialist beetles compared with wild types. The long-hypocotyl mutants also produced leaves with fewer trichomes, greater toughness and a higher carbon to nitrogen ratio (C : N) than wild types. Plants lacking defensive cucurbitacins had 23% longer internodes than the cucurbitacin-producing line. 4We then manipulated the plant phenotype by artificially imposing neighbours' shade on plants with and without cucurbitacins. As expected, plants responded to shade by growing longer hypocotyls and first internodes, but few trade-offs were found between plant line and shade treatment and, although herbivory levels were very low, there was a trend towards reduced damage on shaded plants. 5The use of genetically altered plant lines provided strong evidence for the trade-off hypothesis, while phenotypic manipulations did not support the hypothesis. [source] The role of genotypic diversity in determining grassland community structure under constant environmental conditionsJOURNAL OF ECOLOGY, Issue 5 2007RAJ WHITLOCK Summary 1A recent experiment varied the genetic diversity of model grassland communities under standardized soil and management conditions and at constant initial species diversity. After 5 years' growth, genetically diverse communities retained more species diversity and became more similar in species composition than genetically impoverished communities. 2Here we present the results of further investigation within this experimental system. We proposed that two mechanisms , the first invoking genetically determined and constant differences in plant phenotypes and the second invoking genotype,environment interactions , could each underpin these results. This mechanistic framework was used as a tool to interpret our findings. 3We used inter-simple sequence repeat (ISSR) DNA markers to confirm which of the individuals of six study species initially included in the model communities were unique genotypes. We then used the molecular markers to assess the survival and abundance of each genotype at the end of the 5-year experimental period. 4The DNA marker data were used to create, for the first time, a genotype abundance hierarchy describing the structure of a community at the level of genotypes. This abundance hierarchy revealed wide variation in the abundance of genotypes within species, and large overlaps in the performance of the genotypes of different species. 5Each genotype achieved a consistent level of abundance within genetically diverse communities, which differed from that attained by other genotypes of the same species. The abundance hierarchy of genotypes within species also showed consistency across communities differing in their initial level of genetic diversity, such that species abundance in genetically impoverished communities could be predicted, in part, by genotypic identity. 6Three species (including two canopy-dominants) experienced shifts in their community-level genotype abundance hierarchies that were consistent with an increased influence of genotype,environment interactions in genetically impoverished communities. 7Our results indicate that under relatively constant environmental conditions the species abundance structure of plant communities can in part be predicted from the genotypic composition of their component populations. Genotype,environment interactions also appear to shape the structure of communities under such conditions, although further experiments are needed to clarify the magnitude and mechanism of these effects. [source] An illustrated gardener's guide to transgenic Arabidopsis field experimentsNEW PHYTOLOGIST, Issue 2 2008Martin Frenkel Summary ,,Field studies with transgenic Arabidopsis lines have been performed over 8 yr, to better understand the influence that certain genes have on plant performance. Many (if not most) plant phenotypes cannot be observed under the near constant, low-stress conditions in growth chambers, making field experiments necessary. However, there are challenges in performing such experiments: permission must be obtained and regulations obeyed, the profound influence of uncontrollable biotic and abiotic factors has to be considered, and experimental design has to be strictly controlled. ,,The aim here is to provide inspiration and guidelines for researchers who are not used to setting up such experiments, allowing others to learn from our mistakes. ,, This is believed to be the first example of a ,manual' for field experiments with transgenic Arabidopsis plants. Many of the challenges encountered are common for all field experiments, and many researchers from ecological backgrounds are skilled in such methods. ,,There is huge potential in combining the detailed mechanistic understanding of molecular biologists with ecologists' expertise in examining plant performance under field conditions, and it is suggested that more interdisciplinary collaborations will open up new scientific avenues to aid analyses of the roles of genetic and physiological variation in natural systems. [source] Use of gene transfer technology for functional studies in grapevineAUSTRALIAN JOURNAL OF GRAPE AND WINE RESEARCH, Issue 2010J.R. VIDAL Abstract The understanding of the genetic determinism of plant phenotypes requires the functional annotation of genes governing specific traits including the characterisation of their regulatory networks. A striking feature of the grapevine genome and proteome lies in the existence of large families related to wine attributes that have a higher gene copy number than in other sequenced plants. During speciation, the appearance of new adaptive functions is often based on the evolution of orthologous genes eventually associated with duplication (paralogous sequences) leading to new proteins and expression profiles. The presence of original features in grapevine, including perennial status, vegetative architecture, inflorescence/tendril, flower organisation (corolla), and fleshy fruit of considerable acidity with various flavonoid compounds, makes functional genomics an essential approach to link a gene to a trait. For grapevine, the current lack of high throughput genetic techniques (e.g. induced mutant collections) and the difficulties associated with genetic mapping (allele diversity, chimerism, generation time) highlights the critical role of transgenic technology for characterising gene function. Different techniques are available to obtain information about gene functioning, but the choice of a particular approach depends on the process investigated (e.g. metabolism, developmental, pathogen response) and the experimental purpose (e.g. induction of ectopic functions, promoter studies, subcellular localisation). After a brief overview of the development of grapevine biotechnology, this paper reviews the state-of-the-art gene transfer technology for grapevine and detailed examples of where transgenic technology has proven useful for studying gene function. [source] | ||||||||||