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Physiological Bases (physiological + base)
Selected AbstractsSize-dependent sex allocation in Aconitum gymnandrum (Ranunculaceae): physiological basis and effects of maternal family and environmentPLANT BIOLOGY, Issue 6 2008Z.-G. Zhao Abstract Theory predicts size-dependent sex allocation (SDS): flowers on plants with a high-resource status should have larger investment in females than plants with a low-resource status. Through a pot experiment with Aconitum gymnandrum (Ranunculaceae) in the field, we examined the relationship between sex allocation of individual flowers and plant size for different maternal families under different environmental conditions. We also determined the physiological base of variations in plant size. Our results support the prediction of SDS, and show that female-biased allocation with plant size is consistent under different environmental conditions. Negative correlations within families showed a plastic response of sex allocation to plant size. Negative genetic correlations between sex allocation and plant size at the family level indicate a genetic cause of the SDS pattern, although genetic correlation was influenced by environmental factors. Hence, the size-dependency of sex allocation in this species had both plastic and genetic causes. Furthermore, genotypes that grew large also had higher assimilation ability, thus showing a physiological basis for SDS. [source] Quantitative aspects of the regulation of ovarian development in selected anautogenous Diptera: integration of endocrinology and nutritionENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 2 2001L. Barton Browne Abstract Aspects of the influence of nutrition on the degree of ovarian development in selected anautogenous Diptera are reviewed. The Diptera considered are several mosquito species, with emphasis on Aedes aegypti, the house fly, Musca domestica, the Australian bush fly, M. vetustissima and the blowflies, Lucilia cuprina and Phormia regina. All the selected species display discrete ovarian cycles in which all oocytes destined to reach maturity in a particular ovarian cycle develop synchronously. In these species, the proportion of females maturing oocytes and, where such data exist, the number of oocytes they mature are positively correlated with the amount of any particular nitrogen-containing material ingested or given by enema or by infusion. In addition, the degree of ovarian development may be affected by the chemical composition of nitrogen-containing food. Possible physiological bases for the observed relationships are discussed. Available evidence suggests that whether or not a female matures any oocytes is hormonally regulated and that the number of oocytes matured is probably regulated by the availability of nutrients. Some approaches that might further elucidate the physiological regulatory mechanisms involved in ovarian development are outlined. [source] Evolutionary biology of starvation resistance: what we have learned from DrosophilaJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 5 2007S. RION Abstract Most animals face periods of food shortage and are thus expected to evolve adaptations enhancing starvation resistance (SR). Most of our knowledge of the genetic and physiological bases of those adaptations, their evolutionary correlates and trade-offs, and patterns of within- and among-population variation, comes from studies on Drosophila. In this review, we attempt to synthesize the various facets of evolutionary biology of SR emerging from those studies. Heritable variation for SR is ubiquitous in Drosophila populations, allowing for large responses to experimental selection. Individual flies can also inducibly increase their SR in response to mild nutritional stress (dietary restriction). Both the evolutionary change and the physiological plasticity involve increased accumulation of lipids, changes in carbohydrate and lipid metabolism and reduction in reproduction. They are also typically associated with greater resistance to desiccation and oxidative stress, and with prolonged development and lifespan. These responses are increasingly seen as facets of a shift of the physiology towards a ,survival mode', which helps the animal to survive hard times. The last decade has seen a great progress in revealing the molecular bases of induced responses to starvation, and the first genes contributing to genetic variation in SR have been identified. In contrast, little progress has been made in understanding the ecological significance of SR in Drosophila; in particular it remains unclear to what extent geographical variation in SR reflect differences in natural selection acting on this trait rather than correlated responses to selection on other traits. Drosophila offers a unique opportunity for an integrated study of the manifold aspects of adaptation to nutritional stress. Given that at least some major molecular mechanisms of response to nutritional stress seem common to animals, the insights from Drosophila are likely to apply more generally than just to dipterans or insects. [source] Genomic dissection of drought resistance in durum wheat × wild emmer wheat recombinant inbreed line populationPLANT CELL & ENVIRONMENT, Issue 7 2009ZVI PELEG ABSTRACT Drought is the major factor limiting wheat productivity worldwide. The gene pool of wild emmer wheat, Triticum turgidum ssp. dicoccoides, harbours a rich allelic repertoire for morpho-physiological traits conferring drought resistance. The genetic and physiological bases of drought responses were studied here in a tetraploid wheat population of 152 recombinant inbreed lines (RILs), derived from a cross between durum wheat (cv. Langdon) and wild emmer (acc# G18-16), under contrasting water availabilities. Wide genetic variation was found among RILs for all studied traits. A total of 110 quantitative trait loci (QTLs) were mapped for 11 traits, with LOD score range of 3.0,35.4. Several QTLs showed environmental specificity, accounting for productivity and related traits under water-limited (20 QTLs) or well-watered conditions (15 QTLs), and in terms of drought susceptibility index (22 QTLs). Major genomic regions controlling productivity and related traits were identified on chromosomes 2B, 4A, 5A and 7B. QTLs for productivity were associated with QTLs for drought-adaptive traits, suggesting the involvement of several strategies in wheat adaptation to drought stress. Fifteen pairs of QTLs for the same trait were mapped to seemingly homoeologous positions, reflecting synteny between the A and B genomes. The identified QTLs may facilitate the use of wild alleles for improvement of drought resistance in elite wheat cultivars. [source] Improving water use efficiency in grapevines: potential physiological targets for biotechnological improvementAUSTRALIAN JOURNAL OF GRAPE AND WINE RESEARCH, Issue 2010J. FLEXAS Abstract Improving water use efficiency (WUE) in grapevines is essential for vineyard sustainability under the increasing aridity induced by global climate change. WUE reflects the ratio between the carbon assimilated by photosynthesis and the water lost in transpiration. Maintaining stomata partially closed by regulated deficit irrigation or partial root drying represents an opportunity to increase WUE, although at the expense of decreased photosynthesis and, potentially, decreased yield. It would be even better to achieve increases in WUE by improving photosynthesis without increasing water loses. Although this is not yet possible, it could potentially be achieved by genetic engineering. This review presents current knowledge and relevant results that aim to improve WUE in grapevines by biotechnology and genetic engineering. The expected benefits of these manipulations on WUE of grapevines under water stress conditions are modelled. There are two main possible approaches to achieve this goal: (i) to improve CO2 diffusion to the sites of carboxylation without increasing stomatal conductance; and (ii) to improve the carboxylation efficiency of Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco). The first goal could be attained by increasing mesophyll conductance to CO2, which partly depends on aquaporins. The second approach could be achieved by replacing Rubisco from grapevine with Rubiscos from other C3 species with higher specificity for CO2. In summary, the physiological bases and future prospects for improving grape yield and WUE under drought are established. 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