1,721,291 research outputs found
L'acqua in agricoltura: efficienza d'uso e tolleranza allo stress idrico
No full textIl mantenimento degli elevati standard produttivi delle specie agricole necessita di un continuo ed enorme apporto di acqua. Una delle sfide dell’agricoltura moderna è quella di ridurre in modo significativo i consumi idrici necessari per sostenere le attuali produzioni. Obiettivo di questo capitolo è quello di fornire una panoramica sullo stato dell’arte nello sviluppo di nuove varietà caratterizzate da un minor fabbisogno d’acqua e da una maggior tolleranza alla siccità. I più recenti risultati ottenuti in programmi di breeding assistito e approcci biotecnologici saranno descritti e discussi
Cassette for nucleic acid expression in plants
No full textThe present invention relates to the expression of recombinant nucleic acids in plants. More specifically the invention provides a promoter for the selective expression of genes in stomatal guard cells, gene constructs containing said promoter, expression vectors thereof and plants transformed therewith. The selective expression of genes in stomatal guard cells allows the regulation of their opening/closing states thereby modulating, e.g. increasing, the plant ability to resist to adverse environmental or climatic conditions
Insertional mutagenesis in Arabidopsis : a tool for functional genomic analysis
No full textThe completion of the entire Arabidopsis genome sequence has been recently achieved. Approximately 30% of the predicted genes encode for proteins of unknown function, and only 9% of the genes have been characterized experimentally. Different genetic and molecular tools have been developed to address the functional significance of the genes discovered in EST and genome sequencing programs. Bioinformatic studies can assign putative functions by homology to known genes, while microarray technology can examine global and detailed gene expression patterns. Nevertheless, the identification and characterization of loss-of-function mutations remains a primary tool in functional genomics studies. Insertional mutagenesis approaches are well suited for large-scale functional analysis. Insertions of transposons or T-DNA in specific target genes can be easily detected by reverse genetic PCR-assisted screens. The molecular and phenotypic characterization of the insertional alleles provide vital data on the biological role of the disrupted gene
Breeding for Drought Stress Resistance in Plants
No full textAbstract: Most cropping environments worldwide are suboptimal for plant growth and reproduction. Unfavorable environmental conditions prevent crops from attaining their full yield potential. Abiotic stresses including heat, cold, drought, salinity, and flooding have a major impact on world agriculture, were reducing by 50% the average yield for most crop plants. Among these, water scarcity is the major factor limiting the expansion of agriculture and the single leading cause of crop losses worldwide With the impact of climate change and demographic growth looming, stress-tolerant varieties and climate-resilient crops emerge as relevant and necessary targets to ensure global food security and to improve sustainability in agriculture. Breeding of crops with enhanced stresses tolerance has been particularly compelling, as the related agronomic traits are complex and quantitative in nature, often associated to several loci exhibiting additive effects. Advances in plant genomics have greatly contributed to dissect such complex traits, unraveling the mechanisms underlying the plant response to stress, and opening unprecedented avenues in breeding improved varieties against unfavorable environmental conditions. This chapter will focus on recent successful stories in molecular breeding and biotechnological strategies for crop improvement against abiotic stress, with particular emphasis on drought tolerance
Cassetta per l’espressione ABA-indipendente di acidi nucleici ricombinanti nelle cellule di guardia delle piante
No full textSi intende risolvere il problema dell'espressione cellula-specifica di geni vegetali negli stomi attraverso l'utilizzo del promotore del gene CYP86A2 di Arabidopsis thaliana. Tale gene risulta espresso in modo specifico nelle cellule di guardia che delimitano l'apertura stomatica e presenti sull'epidermide della parte aerea dei vegetali. L'utilizzo del promotore di CYP86A2 consente di esprimere in modo costitutivo e specifico di geni esogeni in cellule di guardia, al fine di ridurre l'apertura della rima stomatica per limitare la perdita d'acqua dai tessuti vegetali. Il gene di Arabidopsis thaliana CYP86A2 è espresso in modo specifico nelle cellule di guardia degli stomi. Il putativo promotore di CYP86A2 è stato isolato e posto a monte del gene reporter GFP (costrutto pCYP86A2:GFP). Le piante transgeniche di Arabidopsis ottenute inseguito alla trasformazione con il costrutto pCYP86A2:GFP evidenziano espressione del reporter unicamente nelle cellule di guardia. Questo dimostra che tale promotore è in grado di guidare l'espressione dei geni posti sotto il suo controllo in modo specifico nelgi stomi. Il promotore di CYP86A2, rappresenta quindi un prezioso strumento per l'espressione stoma-specifica di geni regolatori, al fine di limitare la perdita d'acqua per traspirazione. Questa strategia consente di ottenere piante in grado di meglio tollerare eventi di carenza idrica, e di sostenere elevati livelli produttivi con un ridotto consumo d'acqua
Growth factors and steroid hormones: a complex interplay in the hypothalamic control of reproductive functions
No full textThe mechanisms through which LHRH-secreting neurons are controlled still represent a crucial and debated field of research in the neuroendocrine control of reproduction. In the present review, we have specifically considered two potential signals reaching these hypothalamic neurons: steroid hormones and growth factors. Examples of the relevant physiological role of the interactions between these two families of biologically acting molecules have been provided. In many cases, these interactions occur at the level of hypothalamic astrocytes, which are presently accepted as functional partners of the LHRH-secreting neurons. On the basis of the observations here summarized, we have formulated the hypothesis that a functional co-operation of steroid hormones and growth factors occurring in the hypothalamic astrocytic compartment represents a key factor in the neuroendocrine control of reproductive functions
Analysis of Hybrid Algorithms for the Navier-Stokes Equations with respect to Hydrodynamic Stability Theory
No full textHybrid three-dimensional algorithms for the numerical integration of the incompressible Navier–Stokes equations are analyzed with respect to hydrodynamic stability in both linear and nonlinear fields. The computational schemes are mixed—spectral and finite differences—and are applied to the case of the channel flow driven by constant pressure gradient; time marching is handled with the fractional step method. Different formulations—fully explicit convective term, partially and fully implicit viscous term combined with uniform, stretched, staggered and non-staggered meshes, x-velocity splitted and non-splitted in average and perturbation component – are analyzed by monitoring the evolution in time of both small and finite amplitude perturbations of the mean flow. The results in the linear feld are compared with correspondent solutions of the Orr–Sommerfeld equation; in the nonlinear feld, the comparison is made with results obtained by other authors
- …
