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1.
Nature ; 618(7966): 708-711, 2023 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-37277615

RESUMO

Dust grains absorb half of the radiation emitted by stars throughout the history of the universe, re-emitting this energy at infrared wavelengths1-3. Polycyclic aromatic hydrocarbons (PAHs) are large organic molecules that trace millimetre-size dust grains and regulate the cooling of interstellar gas within galaxies4,5. Observations of PAH features in very distant galaxies have been difficult owing to the limited sensitivity and wavelength coverage of previous infrared telescopes6,7. Here we present James Webb Space Telescope observations that detect the 3.3 µm PAH feature in a galaxy observed less than 1.5 billion years after the Big Bang. The high equivalent width of the PAH feature indicates that star formation, rather than black hole accretion, dominates infrared emission throughout the galaxy. The light from PAH molecules, hot dust and large dust grains and stars are spatially distinct from one another, leading to order-of-magnitude variations in PAH equivalent width and ratio of PAH to total infrared luminosity across the galaxy. The spatial variations we observe suggest either a physical offset between PAHs and large dust grains or wide variations in the local ultraviolet radiation field. Our observations demonstrate that differences in emission from PAH molecules and large dust grains are a complex result of localized processes within early galaxies.

2.
J Exp Bot ; 73(12): 4236-4249, 2022 06 24.
Artigo em Inglês | MEDLINE | ID: mdl-35383843

RESUMO

Increasing grain number through fine-tuning duration of the late reproductive phase (LRP; terminal spikelet to anthesis) without altering anthesis time has been proposed as a genetic strategy to increase yield potential (YP) of wheat. Here we conducted a modelling analysis to evaluate the potential of fine-tuning LRP in raising YP in irrigated mega-environments. Using the known optimal anthesis and sowing date of current elite benchmark genotypes, we applied a gene-based phenology model for long-term simulations of phenological stages and yield-related variables of all potential germplasm with the same duration to anthesis as the benchmark genotypes. These diverse genotypes had the same duration to anthesis but varying LRP duration. Lengthening LRP increased YP and harvest index by increasing grain number to some extent and an excessively long LRP reduced YP due to reduced time for canopy construction for high biomass production of pre-anthesis phase. The current elite genotypes could have their LRP extended for higher YP in most sites. Genotypes with a ratio of the duration of LRP to pre-anthesis phase of about 0.42 ensured high yields (≥95% of YP) with their optimal sowing and anthesis dates. Optimization of intermediate growth stages could be further evaluated in breeding programmes to improve YP.


Assuntos
Melhoramento Vegetal , Triticum , Biomassa , Grão Comestível , Reprodução , Triticum/genética
3.
J Exp Bot ; 73(19): 6558-6574, 2022 11 02.
Artigo em Inglês | MEDLINE | ID: mdl-35768163

RESUMO

A major challenge for the estimation of crop traits (biophysical variables) from canopy reflectance is the creation of a high-quality training dataset. To address this problem, this research investigated a conceptual framework by integrating a crop growth model with a radiative transfer model to introduce biological constraints in a synthetic training dataset. In addition to the comparison of two datasets without and with biological constraints, we also investigated the effects of observation geometry, retrieval method, and wavelength range on estimation accuracy of four crop traits (leaf area index, leaf chlorophyll content, leaf dry matter, and leaf water content) of wheat. The theoretical analysis demonstrated potential advantages of adding biological constraints in synthetic training datasets as well as the capability of deep learning. Additionally, the predictive models were validated on real unmanned aerial vehicle-based multispectral images collected from wheat plots contrasting in canopy structure. The predictive model trained over a synthetic dataset with biological constraints enabled the prediction of leaf water content from using wavelengths in the visible to near infrared range based on the correlations between crop traits. Our findings presented the potential of the proposed conceptual framework in simultaneously retrieving multiple crop traits from canopy reflectance for applications in precision agriculture and plant breeding.


Assuntos
Aprendizado Profundo , Melhoramento Vegetal , Clorofila , Folhas de Planta , Triticum , Água
4.
J Exp Bot ; 72(20): 7203-7218, 2021 10 26.
Artigo em Inglês | MEDLINE | ID: mdl-34245278

RESUMO

To maximize the grain yield of spring wheat, flowering needs to coincide with the optimal flowering period (OFP) by minimizing frost and heat stress on reproductive development. This global study conducted a comprehensive modelling analysis of genotype, environment, and management to identify the OFPs for sites in irrigated mega-environments of spring wheat where the crop matures during a period of increasing temperatures. We used a gene-based phenology model to conduct long-term simulation analysis with parameterized genotypes to identify OFPs and optimal sowing dates for sites in irrigated mega-environments, considering the impacts of frost and heat stress on yield. The validation results showed that the gene-based model accurately predicted wheat heading dates across global wheat environments. The long-term simulations indicated that frost and heat stress significantly advanced or delayed OFPs and shrank the durations of OFPs in irrigated mega-environments when compared with OFPs where the model excluded frost and heat stress impacts. The simulation results (incorporating frost and heat penalties on yield) also showed that earlier flowering generally resulted in higher yields, and early sowing dates and/or early flowering genotypes were suggested to achieve early flowering. These results provided an interpretation of the regulation of wheat flowering to the OFP by the selection of sowing date and cultivar to achieve higher yields in irrigated mega-environments.


Assuntos
Grão Comestível , Triticum , Simulação por Computador , Estações do Ano , Temperatura , Triticum/genética
5.
Theor Appl Genet ; 134(6): 1845-1866, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-34076731

RESUMO

KEY MESSAGE: High-throughput phenotyping (HTP) is in its infancy for deployment in large-scale breeding programmes. With the ability to measure correlated traits associated with physiological ideotypes, in-field phenotyping methods are available for screening of abiotic stress responses. As cropping environments become more hostile and unpredictable due to the effects of climate change, the need to characterise variability across spatial and temporal scales will become increasingly important. The sensor technologies that have enabled HTP from macroscopic through to satellite sensors may also be utilised here to complement spatial characterisation using envirotyping, which can improve estimations of genotypic performance across environments by better accounting for variation at the plot, trial and inter-trial levels. Climate change is leading to increased variation at all physical and temporal scales in the cropping environment. Maintaining yield stability under circumstances with greater levels of abiotic stress while capitalising upon yield potential in good years, requires approaches to plant breeding that target the physiological limitations to crop performance in specific environments. This requires dynamic modelling of conditions within target populations of environments, GxExM predictions, clustering of environments so breeding trajectories can be defined, and the development of screens that enable selection for genetic gain to occur. High-throughput phenotyping (HTP), combined with related technologies used for envirotyping, can help to address these challenges. Non-destructive analysis of the morphological, biochemical and physiological qualities of plant canopies using HTP has great potential to complement whole-genome selection, which is becoming increasingly common in breeding programmes. A range of novel analytic techniques, such as machine learning and deep learning, combined with a widening range of sensors, allow rapid assessment of large breeding populations that are repeatable and objective. Secondary traits underlying radiation use efficiency and water use efficiency can be screened with HTP for selection at the early stages of a breeding programme. HTP and envirotyping technologies can also characterise spatial variability at trial and within-plot levels, which can be used to correct for spatial variations that confound measurements of genotypic values. This review explores HTP for abiotic stress selection through a physiological trait lens and additionally investigates the use of envirotyping and EC to characterise spatial variability at all physical scales in METs.


Assuntos
Mudança Climática , Produtos Agrícolas/genética , Melhoramento Vegetal , Estresse Fisiológico , Genótipo , Modelos Genéticos , Fenótipo , Seleção Genética
6.
Vascular ; 29(3): 372-379, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32951559

RESUMO

BACKGROUND: There are limited data on outcomes for patients with peripheral artery disease undergoing endovascular revascularization by multi-disciplinary teams in a community hospital setting. METHODS: From January 2015 through December 2015, we assembled a multi-disciplinary program comprised of cardiologists, surgeons, radiologists, nurses, and administrative staff for managing patients with peripheral artery disease undergoing endovascular revascularization. Demographic, procedural, and outcomes data were collected with use of a template from the Society for Vascular Surgery Vascular Quality Initiative database. We compared characteristics and outcomes of patients with intermittent claudication and critical limb ischemia. We used Kaplan-Meier methods to estimate the rate of overall survival and freedom from rehospitalization between groups. RESULTS: After excluding patients with acute limb ischemia (n = 5), peripheral intervention to the upper extremity (n = 6), or abdominal aorta (n = 11), there were 82 patients in the study cohort; 45 had intermittent claudication and 37 had critical limb ischemia. Baseline and procedural characteristics were similar between groups, although critical limb ischemia patients were more likely to have hyperlipidemia (75.7% vs. 53.3%, P = .42). Procedural success was achieved in 91.3% of cases. Actionable access site bleeding occurred in 2.4% of patients. High rates of aspirin (91.5%) and statin (87.8%) were noted at discharge. After two years of post endovascular revascularization, survival was 57.5% for critical limb ischemia patients and 94.4% for intermittent claudication patients (P < .001). Freedom from rehospitalization was 32.7% for critical limb ischemia patients and 83.5% for intermittent claudication patients (P < .001). CONCLUSIONS: We found that favorable outcomes may be achieved with a multi-disciplinary peripheral artery disease program at community hospitals. The incorporation of quality improvement practices may further help to develop standardized and regionalized approaches to care delivery for patients with peripheral artery disease.


Assuntos
Procedimentos Endovasculares , Hospitais Comunitários , Claudicação Intermitente/terapia , Isquemia/terapia , Doença Arterial Periférica/terapia , Idoso , Idoso de 80 Anos ou mais , Estado Terminal , Procedimentos Endovasculares/efeitos adversos , Procedimentos Endovasculares/mortalidade , Feminino , Humanos , Claudicação Intermitente/diagnóstico por imagem , Claudicação Intermitente/mortalidade , Claudicação Intermitente/fisiopatologia , Isquemia/diagnóstico por imagem , Isquemia/mortalidade , Isquemia/fisiopatologia , Masculino , Pessoa de Meia-Idade , Equipe de Assistência ao Paciente , Readmissão do Paciente , Doença Arterial Periférica/diagnóstico por imagem , Doença Arterial Periférica/mortalidade , Doença Arterial Periférica/fisiopatologia , Avaliação de Programas e Projetos de Saúde , Melhoria de Qualidade , Indicadores de Qualidade em Assistência à Saúde , Medição de Risco , Fatores de Risco , Fatores de Tempo , Resultado do Tratamento
7.
Ann Vasc Surg ; 65: 283.e13-283.e17, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-31705991

RESUMO

CT angiography with multislice detector has become the preferred method for assessment of hemodynamically stable patients suspected of great vessel injury from iatrogenic and blunt trauma. The CT images obtained can be transformed into a three-dimensional (3D) model using the software within minutes. This allows the clinician to evaluate the injury and the injury's proximity to other vital structures for operative planning. The 3D modeling provides geometric calibration of the c-arm or image intensifier in regard to optimal cranial/caudal and oblique angles to evaluate and treat the vessel injury. We describe a case of a 28-year-old female undergoing a cesarian section and hysterectomy for placenta percreta, who sustained a right subclavian artery injury (presumed wire injury) from inadvertent right common carotid artery cannulation during placement of a right internal jugular 8 French resuscitative central line. A 3D model was created from the CT angiography to locate the small pseudoaneurysm of the right subclavian artery. The optimal projection was obtained using the 3D reconstructive software to visualize the injury and its relation to the right vertebral artery ostium for endovascular planning. This preoperative maneuver allowed for limited radiation exposure and contrast volume used to treat the injury.


Assuntos
Implante de Prótese Vascular , Angiografia por Tomografia Computadorizada , Meios de Contraste/administração & dosagem , Procedimentos Endovasculares , Doença Iatrogênica , Imageamento Tridimensional , Tomografia Computadorizada Multidetectores , Modelagem Computacional Específica para o Paciente , Radiografia Intervencionista , Artéria Subclávia/diagnóstico por imagem , Artéria Subclávia/cirurgia , Cirurgia Assistida por Computador , Lesões do Sistema Vascular/diagnóstico por imagem , Lesões do Sistema Vascular/cirurgia , Adulto , Implante de Prótese Vascular/efeitos adversos , Cateterismo Venoso Central/efeitos adversos , Angiografia por Tomografia Computadorizada/efeitos adversos , Meios de Contraste/efeitos adversos , Procedimentos Endovasculares/efeitos adversos , Feminino , Fluoroscopia , Humanos , Imageamento Tridimensional/efeitos adversos , Tomografia Computadorizada Multidetectores/efeitos adversos , Valor Preditivo dos Testes , Gravidez , Doses de Radiação , Exposição à Radiação/efeitos adversos , Exposição à Radiação/prevenção & controle , Radiografia Intervencionista/efeitos adversos , Artéria Subclávia/lesões , Artéria Subclávia/fisiopatologia , Cirurgia Assistida por Computador/efeitos adversos , Fatores de Tempo , Resultado do Tratamento , Lesões do Sistema Vascular/etiologia , Lesões do Sistema Vascular/fisiopatologia
8.
J Exp Bot ; 70(9): 2535-2548, 2019 04 29.
Artigo em Inglês | MEDLINE | ID: mdl-30918963

RESUMO

Early vigour, or faster early leaf area development, has been considered an important trait for rainfed wheat in dryland regions such as Australia. However, early vigour is a genetically complex trait, and results from field experiments have been highly variable. Whether early vigour can lead to improved water use efficiency and crop yields is strongly dependent on climate and management conditions across the entire growing season. Here, we present a modelling framework for simulating the impact of early vigour on wheat growth and yield at eight sites representing the major climate types in Australia. On a typical soil with plant available water capacity (PAWC) of 147 mm, simulated yield increase with early vigour associated with larger seed size was on average 4% higher compared with normal vigour wheat. Early vigour through selection of doubled early leaf sizes could increase yield by 16%. Increase in yield was mainly from increase in biomass and grain number, and was reduced at sites with seasonal rainfall plus initial soil water <300 mm. Opportunities exists for development of early vigour wheat varieties for wetter sites. Soil PAWC could play a significant role in delivering the benefit of early vigour and would require particular attention.


Assuntos
Folhas de Planta/fisiologia , Triticum/fisiologia , Austrália , Genótipo , Folhas de Planta/genética , Triticum/genética
9.
J Exp Bot ; 70(9): 2389-2401, 2019 04 29.
Artigo em Inglês | MEDLINE | ID: mdl-30921457

RESUMO

In spite of the increasing expectation for process-based crop modelling to capture genotype (G) by environment (E) by management (M) interactions to support breeding selections, it remains a challenge to use current crop models to accurately predict phenotypes from genotypes or from candidate genes. We use wheat as a target crop and the APSIM farming systems model (Holzworth et al., 2014) as an example to analyse the current status of process-based crop models with a major focus on need to improve simulation of specific eco-physiological processes and their linkage to underlying genetic controls. For challenging production environments in Australia, we examine the potential opportunities to capture physiological traits, and to integrate genetic and molecular approaches for future model development and applications. Model improvement will require both reducing the uncertainty in simulating key physiological processes and enhancing the capture of key observable traits and underlying genetic control of key physiological responses to environment. An approach consisting of three interactive stages is outlined to (i) improve modelling of crop physiology, (ii) develop linkage from model parameter to genotypes and further to loci or alleles, and (iii) further link to gene expression pathways. This helps to facilitate the integration of modelling, phenotyping, and functional gene detection and to effectively advance modelling of G×E×M interactions. While gene-based modelling is not always needed to simulate G×E×M, including well-understood gene effects can improve the estimation of genotype effects and prediction of phenotypes. Specific examples are given for enhanced modelling of wheat in the APSIM framework.


Assuntos
Produtos Agrícolas/genética , Produtos Agrícolas/fisiologia , Genótipo , Modelos Genéticos , Fenótipo , Triticum/genética , Triticum/fisiologia
10.
Vasc Med ; 24(5): 455-460, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31543059

RESUMO

Functional popliteal artery entrapment syndrome (FPAES) presents a challenge for clinicians in the field today. The relative rarity of the disease coupled with its affliction primarily in young, athletic individuals makes it a difficult condition to diagnose. Treatment modalities have been limited to surgical intervention, with more novel methods being developed over the last several years. We present a case report and review the diagnostic and management approaches for FPAES, shedding light on proposed future interventions.


Assuntos
Arteriopatias Oclusivas/diagnóstico por imagem , Arteriopatias Oclusivas/terapia , Artéria Poplítea/diagnóstico por imagem , Arteriopatias Oclusivas/epidemiologia , Arteriopatias Oclusivas/fisiopatologia , Constrição Patológica , Humanos , Artéria Poplítea/fisiopatologia , Valor Preditivo dos Testes , Prognóstico , Fatores de Risco
11.
Nature ; 493(7430): 62-5, 2013 Jan 03.
Artigo em Inglês | MEDLINE | ID: mdl-23282362

RESUMO

Dwarf satellite galaxies are thought to be the remnants of the population of primordial structures that coalesced to form giant galaxies like the Milky Way. It has previously been suspected that dwarf galaxies may not be isotropically distributed around our Galaxy, because several are correlated with streams of H I emission, and may form coplanar groups. These suspicions are supported by recent analyses. It has been claimed that the apparently planar distribution of satellites is not predicted within standard cosmology, and cannot simply represent a memory of past coherent accretion. However, other studies dispute this conclusion. Here we report the existence of a planar subgroup of satellites in the Andromeda galaxy (M 31), comprising about half of the population. The structure is at least 400 kiloparsecs in diameter, but also extremely thin, with a perpendicular scatter of less than 14.1 kiloparsecs. Radial velocity measurements reveal that the satellites in this structure have the same sense of rotation about their host. This shows conclusively that substantial numbers of dwarf satellite galaxies share the same dynamical orbital properties and direction of angular momentum. Intriguingly, the plane we identify is approximately aligned with the pole of the Milky Way's disk and with the vector between the Milky Way and Andromeda.

12.
Ann Vasc Surg ; 60: 479.e1-479.e4, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31201970

RESUMO

Septic thrombophlebitis is a rare diagnosis in this era of widespread antibiotic usage. The clinical diagnosis requires astute clinical suspicion and evaluation. We describe an asplenic 63-year-old woman who presented to the emergency department with a 24-hour history of a tender, swollen, right neck and upper chest wall. She denied any recent illnesses, but two years before, she was hospitalized and treated for Streptococcus pneumoniae meningitis and endocarditis. An enhanced computed tomography scan demonstrated inflammatory changes around a thrombosed right internal jugular vein, which extended to the brachiocephalic/superior vena cava junction. A retropharyngeal effusion was present, but no pulmonary or oropharyngeal abscess was identified. Lemierre's syndrome, although rare, must be recognized promptly to reduce morbidity and mortality associated with this condition.


Assuntos
Fusobacterium necrophorum/isolamento & purificação , Síndrome de Lemierre/microbiologia , Sepse/microbiologia , Tromboflebite/microbiologia , Antibacterianos/uso terapêutico , Anticoagulantes/uso terapêutico , Feminino , Humanos , Síndrome de Lemierre/diagnóstico por imagem , Síndrome de Lemierre/tratamento farmacológico , Pessoa de Meia-Idade , Sepse/diagnóstico , Sepse/tratamento farmacológico , Tromboflebite/diagnóstico por imagem , Tromboflebite/tratamento farmacológico , Resultado do Tratamento
13.
Glob Chang Biol ; 22(2): 921-33, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26432666

RESUMO

By accelerating crop development, warming climates may result in mismatches between key sensitive growth stages and extreme climate events, with severe consequences for crop yield and food security. Using recent estimates of gene responses to vernalization and photoperiod in wheat, we modelled the flowering times of all 'potential' genotypes as influenced by the velocity of climate change across the Australian wheatbelt. In the period 1957-2010, seasonal increases in temperature of 0.012 °C yr(-1) were recorded and changed flowering time of a mid-season wheat genotype by an average -0.074 day yr(-1) , with flowering 'velocity' of up to 0.95 km yr(-1) towards the coastal edges of the wheatbelt; this is an estimate of how quickly the given genotype would have to be 'moved' across the landscape to maintain its original flowering time. By 2030, these national changes are projected to accelerate by up to 3-fold for seasonal temperature and by up to 5-fold for flowering time between now and 2030, with average national shifts in flowering time of 0.33 and 0.41 day yr(-1) between baseline and the worst climate scenario tested for 2030 and 2050, respectively. Without new flowering alleles in commercial germplasm, the life cycle of wheat crops is predicted to shorten by 2 weeks by 2030 across the wheatbelt for the most pessimistic climate scenario. While current cultivars may be otherwise suitable for future conditions, they will flower earlier due to warmer temperatures. To allow earlier sowing to escape frost, heat and terminal drought, and to maintain current growing period of early-sown wheat crops in the future, breeders will need to develop and/or introduce new genetic sources for later flowering, more so in the eastern part of the wheatbelt.


Assuntos
Mudança Climática , Flores/crescimento & desenvolvimento , Triticum/crescimento & desenvolvimento , Austrália , Modelos Teóricos , Melhoramento Vegetal/métodos , Estações do Ano , Temperatura
14.
J Exp Bot ; 66(12): 3611-23, 2015 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-25922479

RESUMO

Radiant spring frosts occurring during reproductive developmental stages can result in catastrophic yield loss for wheat producers. To better understand the spatial and temporal variability of frost, the occurrence and impact of frost events on rain-fed wheat production was estimated across the Australian wheatbelt for 1957-2013 using a 0.05 ° gridded weather data set. Simulated yield outcomes at 60 key locations were compared with those for virtual genotypes with different levels of frost tolerance. Over the last six decades, more frost events, later last frost day, and a significant increase in frost impact on yield were found in certain regions of the Australian wheatbelt, in particular in the South-East and West. Increasing trends in frost-related yield losses were simulated in regions where no significant trend of frost occurrence was observed, due to higher mean temperatures accelerating crop development and causing sensitive post-heading stages to occur earlier, during the frost risk period. Simulations indicated that with frost-tolerant lines the mean national yield could be improved by up to 20% through (i) reduced frost damage (~10% improvement) and (ii) the ability to use earlier sowing dates (adding a further 10% improvement). In the simulations, genotypes with an improved frost tolerance to temperatures 1 °C lower than the current 0 °C reference provided substantial benefit in most cropping regions, while greater tolerance (to 3 °C lower temperatures) brought further benefits in the East. The results indicate that breeding for improved reproductive frost tolerance should remain a priority for the Australian wheat industry, despite warming climates.


Assuntos
Congelamento , Triticum/crescimento & desenvolvimento , Adaptação Fisiológica/genética , Austrália , Simulação por Computador , Ecótipo , Genótipo , Geografia , Estações do Ano , Triticum/genética , Triticum/fisiologia
15.
Glob Chang Biol ; 21(11): 4115-27, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-26152643

RESUMO

Characterization of drought environment types (ETs) has proven useful for breeding crops for drought-prone regions. Here, we consider how changes in climate and atmospheric carbon dioxide (CO2 ) concentrations will affect drought ET frequencies in sorghum and wheat systems of northeast Australia. We also modify APSIM (the Agricultural Production Systems Simulator) to incorporate extreme heat effects on grain number and weight, and then evaluate changes in the occurrence of heat-induced yield losses of more than 10%, as well as the co-occurrence of drought and heat. More than six million simulations spanning representative locations, soil types, management systems, and 33 climate projections led to three key findings. First, the projected frequency of drought decreased slightly for most climate projections for both sorghum and wheat, but for different reasons. In sorghum, warming exacerbated drought stresses by raising the atmospheric vapor pressure deficit and reducing transpiration efficiency (TE), but an increase in TE due to elevated CO2 more than offset these effects. In wheat, warming reduced drought stress during spring by hastening development through winter and reducing exposure to terminal drought. Elevated CO2 increased TE but also raised radiation-use efficiency and overall growth rates and water use, thereby offsetting much of the drought reduction from warming. Second, adding explicit effects of heat on grain number and grain size often switched projected yield impacts from positive to negative. Finally, although average yield losses associated with drought will remain generally higher than that for heat stress for the next half century, the relative importance of heat is steadily growing. This trend, as well as the likely high degree of genetic variability in heat tolerance, suggests that more emphasis on heat tolerance is warranted in breeding programs. At the same time, work on drought tolerance should continue with an emphasis on drought that co-occurs with extreme heat.


Assuntos
Dióxido de Carbono/metabolismo , Mudança Climática , Secas , Temperatura Alta , Sorghum/crescimento & desenvolvimento , Triticum/crescimento & desenvolvimento , Produtos Agrícolas/crescimento & desenvolvimento , New South Wales , Queensland , Estações do Ano
16.
Nature ; 461(7260): 66-9, 2009 Sep 03.
Artigo em Inglês | MEDLINE | ID: mdl-19727194

RESUMO

In hierarchical cosmological models, galaxies grow in mass through the continual accretion of smaller ones. The tidal disruption of these systems is expected to result in loosely bound stars surrounding the galaxy, at distances that reach 10-100 times the radius of the central disk. The number, luminosity and morphology of the relics of this process provide significant clues to galaxy formation history, but obtaining a comprehensive survey of these components is difficult because of their intrinsic faintness and vast extent. Here we report a panoramic survey of the Andromeda galaxy (M31). We detect stars and coherent structures that are almost certainly remnants of dwarf galaxies destroyed by the tidal field of M31. An improved census of their surviving counterparts implies that three-quarters of M31's satellites brighter than M(v) = -6 await discovery. The brightest companion, Triangulum (M33), is surrounded by a stellar structure that provides persuasive evidence for a recent encounter with M31. This panorama of galaxy structure directly confirms the basic tenets of the hierarchical galaxy formation model and reveals the shared history of M31 and M33 in the unceasing build-up of galaxies.

17.
J Exp Bot ; 65(20): 5849-65, 2014 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-25148833

RESUMO

Prediction of wheat phenology facilitates the selection of cultivars with specific adaptations to a particular environment. However, while QTL analysis for heading date can identify major genes controlling phenology, the results are limited to the environments and genotypes tested. Moreover, while ecophysiological models allow accurate predictions in new environments, they may require substantial phenotypic data to parameterize each genotype. Also, the model parameters are rarely related to all underlying genes, and all the possible allelic combinations that could be obtained by breeding cannot be tested with models. In this study, a QTL-based model is proposed to predict heading date in bread wheat (Triticum aestivum L.). Two parameters of an ecophysiological model (V sat and P base , representing genotype vernalization requirements and photoperiod sensitivity, respectively) were optimized for 210 genotypes grown in 10 contrasting location × sowing date combinations. Multiple linear regression models predicting V sat and P base with 11 and 12 associated genetic markers accounted for 71 and 68% of the variance of these parameters, respectively. QTL-based V sat and P base estimates were able to predict heading date of an independent validation data set (88 genotypes in six location × sowing date combinations) with a root mean square error of prediction of 5 to 8.6 days, explaining 48 to 63% of the variation for heading date. The QTL-based model proposed in this study may be used for agronomic purposes and to assist breeders in suggesting locally adapted ideotypes for wheat phenology.


Assuntos
Flores/genética , Genoma de Planta/genética , Locos de Características Quantitativas/genética , Triticum/genética , Adaptação Fisiológica , Cruzamento , Meio Ambiente , Flores/fisiologia , Flores/efeitos da radiação , Genótipo , Modelos Biológicos , Fenótipo , Fotoperíodo , Fatores de Tempo , Triticum/fisiologia , Triticum/efeitos da radiação
18.
New Phytol ; 198(3): 801-820, 2013 May.
Artigo em Inglês | MEDLINE | ID: mdl-23425331

RESUMO

Plant response to drought is complex, so that traits adapted to a specific drought type can confer disadvantage in another drought type. Understanding which type(s) of drought to target is of prime importance for crop improvement. Modelling was used to quantify seasonal drought patterns for a check variety across the Australian wheatbelt, using 123 yr of weather data for representative locations and managements. Two other genotypes were used to simulate the impact of maturity on drought pattern. Four major environment types summarized the variability in drought pattern over time and space. Severe stress beginning before flowering was common (44% of occurrences), with (24%) or without (20%) relief during grain filling. High variability occurred from year to year, differing with geographical region. With few exceptions, all four environment types occurred in most seasons, for each location, management system and genotype. Applications of such environment characterization are proposed to assist breeding and research to focus on germplasm, traits and genes of interest for target environments. The method was applied at a continental scale to highly variable environments and could be extended to other crops, to other drought-prone regions around the world, and to quantify potential changes in drought patterns under future climates.


Assuntos
Produtos Agrícolas , Secas , Modelos Teóricos , Triticum/fisiologia , Austrália , Simulação por Computador , Flores/fisiologia , Genótipo , Chuva , Estações do Ano , Solo/química , Água , Tempo (Meteorologia)
19.
J Exp Bot ; 64(1): 143-60, 2013 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-23213136

RESUMO

In wheat, tillering and water-soluble carbohydrates (WSCs) in the stem are potential traits for adaptation to different environments and are of interest as targets for selective breeding. This study investigated the observation that a high stem WSC concentration (WSCc) is often related to low tillering. The proposition tested was that stem WSC accumulation is plant density dependent and could be an emergent property of tillering, whether driven by genotype or by environment. A small subset of recombinant inbred lines (RILs) contrasting for tillering was grown at different plant densities or on different sowing dates in multiple field experiments. Both tillering and WSCc were highly influenced by the environment, with a smaller, distinct genotypic component; the genotype × environment range covered 350-750 stems m(-2) and 25-210 mg g(-1) WSCc. Stem WSCc was inversely related to stem number m(-2), but genotypic rankings for stem WSCc persisted when RILs were compared at similar stem density. Low tillering-high WSCc RILs had similar leaf area index, larger individual leaves, and stems with larger internode cross-section and wall area when compared with high tillering-low WSCc RILs. The maximum number of stems per plant was positively associated with growth and relative growth rate per plant, tillering rate and duration, and also, in some treatments, with leaf appearance rate and final leaf number. A common threshold of the red:far red ratio (0.39-0.44; standard error of the difference=0.055) coincided with the maximum stem number per plant across genotypes and plant densities, and could be effectively used in crop simulation modelling as a 'cut-off' rule for tillering. The relationship between tillering, WSCc, and their component traits, as well as the possible implications for crop simulation and breeding, is discussed.


Assuntos
Metabolismo dos Carboidratos , Caules de Planta/crescimento & desenvolvimento , Triticum/crescimento & desenvolvimento , Triticum/metabolismo , Água/química , Biomassa , Genótipo , Endogamia , Luz , Modelos Biológicos , Folhas de Planta/fisiologia , Estações do Ano , Solubilidade , Triticum/genética
20.
Plant Phenomics ; 5: 0055, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37234427

RESUMO

It is valuable to develop a generic model that can accurately estimate the leaf area index (LAI) of wheat from unmanned aerial vehicle-based multispectral data for diverse soil backgrounds without any ground calibration. To achieve this objective, 2 strategies were investigated to improve our existing random forest regression (RFR) model, which was trained with simulations from a radiative transfer model (PROSAIL). The 2 strategies consisted of (a) broadening the reflectance domain of soil background to generate training data and (b) finding an appropriate set of indicators (band reflectance and/or vegetation indices) as inputs of the RFR model. The RFR models were tested in diverse soils representing varying soil types in Australia. Simulation analysis indicated that adopting both strategies resulted in a generic model that can provide accurate estimation for wheat LAI and is resistant to changes in soil background. From validation on 2 years of field trials, this model achieved high prediction accuracy for LAI over the entire crop cycle (LAI up to 7 m2 m-2) (root mean square error (RMSE): 0.23 to 0.89 m2 m-2), including for sparse canopy (LAI less than 0.3 m2 m-2) grown on different soil types (RMSE: 0.02 to 0.25 m2 m-2). The model reliably captured the seasonal pattern of LAI dynamics for different treatments in terms of genotypes, plant densities, and water-nitrogen managements (correlation coefficient: 0.82 to 0.98). With appropriate adaptations, this framework can be adjusted to any type of sensors to estimate various traits for various species (including but not limited to LAI of wheat) in associated disciplines, e.g., crop breeding, precision agriculture, etc.

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