scholarly journals Provenance modulates sensitivity of stored seeds of the Australian native grass Neurachne alopecuroidea to temperature and moisture availability

2019 ◽  
Vol 67 (2) ◽  
pp. 106 ◽  
Author(s):  
Friday Gray ◽  
Anne Cochrane ◽  
Pieter Poot
Keyword(s):  
Population Variation ◽  
Local Climate ◽  
Moisture Availability ◽  
Different Temperatures ◽  
The Common ◽  
Gradient Plate ◽  
Moisture Conditions ◽  
Peg 8000 ◽  
Temperature Optima ◽  
Western Australian

In the present study we assessed the sensitivity of stored seeds of the common grass Neurachne alopecuroidea R.Br. from south-western Australian sources to varying temperature and moisture conditions as a tool to anticipate potential adaptability of seeds to climate change. We examined among-population germination responses, focusing on germination of excised seeds to overcome possible dormancy imparted by the lemma and palea. We hypothesised that temperature above and below the optimum and low moisture potentials would adversely affect germination, and that conditions for successful germination would be associated with the local climate at each seed source site. Experiment 1 used a bi-directional temperature gradient plate to measure responses to constant and alternating temperatures (5–40°C). Experiment 2 examined responses to moisture availability using polyethylene glycol (PEG 8000) solutions at different temperatures. Temperature optima varied among populations with significant reductions in germination occurring only below 15°C. Germination speed and success declined with decreasing moisture availability, with greater impact at higher temperatures. Significant population variation was observed. Tolerance to temperature and moisture availability was higher than expected and some of this variation suggests adaptation to local climates across the species Western Australian distribution. We discuss these results in the context of seed use in restoration and global warming.

Comparison of North Carolina, Georgia, and Florida Isolates of Cylindrocladium parasiticum

1999 ◽  
Vol 26 (2) ◽  
pp. 80-84
Author(s):  
J. E. Hollowell ◽  
B. B. Shew ◽  
M. K. Beute
Keyword(s):  
North Carolina ◽  
Root Rot ◽  
Regional Differences ◽  
Black Rot ◽  
Temperature Growth ◽  
Seedling Disease ◽  
Cylindrocladium Parasiticum ◽  
Temperature Controlled ◽  
Gradient Plate ◽  
Temperature Optima

Abstract Thirteen isolates of Cylindrocladium parasiticum Crous, Wingfield & Alfenas from North Carolina and 11 from Georgia were grown on plates of PDA at 20,25, and 30 C on a temperature-gradient plate. Culture diameters were measured daily for 6 d. Significant differences were not observed among isolates grown at 20 C and cultures was smaller as compared with those grown at 25 and 30 C. At 25 and 30 C, isolates varied consistently in growth. On average, Georgia isolates grew slightly less than North Carolina isolates, and all isolates grew better at the warmer temperature. Growth of three North Carolina isolates was compared to four Florida isolates in a second experiment. Florida isolates grew significantly faster than North Carolina isolates at all temperatures. Isolates from the three states were compared for their ability to cause root rotting on peanut at 25 and 30 C. Plants were grown in soil infested at a standardized inoculum density in temperature-controlled water bath tanks for 7 wk at which time roots were rated for Cylindrocladium black rot development. Georgia isolates caused more root rot than either North Carolina or Florida isolates at both temperatures and also caused more seedling disease. State effects were significant; Florida isolates caused less root rot than Georgia isolates. Temperature by state interactions were not significant which means that high temperature-tolerant isolates of C. parasiticum have not evolved from regional differences in soil temperature. Further, North Carolina field isolates do not appear to have changed in temperature optima since the 1970s.

scholarly journals Effect of Temperature and Moisture Period on Infection of Rhododendron ‘Cunningham's White’ by Phytophthora ramorum

2009 ◽  
Vol 99 (9) ◽  
pp. 1045-1052 ◽  
Author(s):  
Paul W. Tooley ◽  
Marsha Browning ◽  
Kerrie L. Kyde ◽  
Dana Berner
Keyword(s):  
The United States ◽  
Phytophthora Ramorum ◽  
Effect Of Temperature ◽  
Optimum Temperature ◽  
Detached Leaf ◽  
Wide Range ◽  
Effects Of Temperature ◽  
Gradient Plate ◽  
Whole Plants ◽  
Moisture Conditions

We investigated the temperature and moisture conditions that allow Phytophthora ramorum to infect Rhododendron ‘Cunningham's White’. Most experiments were performed with a single P. ramorum isolate from the NA1 clonal lineage. For whole plants incubated in dew chambers at 10 to 31°C, the greatest proportion of diseased leaves, 77.5%, occurred at the optimum temperature of 20.5°C. Disease occurred over the entire range of temperatures tested, although amounts of disease were minor at the temperature extremes. For whole plants exposed to varying dew periods at 20°C and then incubated at 20°C for 7 days, a dew period as short as 1 h resulted in a small amount of disease; however, at least 4 h of dew were required for >10% of the leaves to become diseased. Moisture periods of 24 and 48 h resulted in the greatest number of diseased leaves. In detached-leaf, temperature-gradient-plate experiments, incubation at 22°C resulted in the greatest disease severity, followed by 18°C and then 14°C. In detached-leaf, moisture-tent experiments, a 1-h moisture period was sufficient to cause disease on 67 to 73% of leaves incubated for 7 days at 20°C. A statistical model for disease development that combined the effects of temperature and moisture period was generated using nonlinear regression. Our results define temperature and moisture conditions which allow infection by P. ramorum on Cunningham's White rhododendron, and show that P. ramorum is able to infect this host over a wide range of temperatures and moisture levels. The results indicate that P. ramorum has the potential to become established in parts of the United States that are outside its current range.

Modeling of Liquid-Liquid Demixing Curve in Lead-Zinc Binary System

2018 ◽  
Vol 18 ◽  
pp. 49-54
Author(s):  
Naceur Amel ◽  
Adjadj Fouzia
Keyword(s):  
Mathematical Model ◽  
Free Energy ◽  
Phase Separation ◽  
Binary System ◽  
Free Energies ◽  
Common Tangent ◽  
Different Temperatures ◽  
Lead Zinc ◽  
The Common ◽  
Zn Alloys

In this work we discussed the modeling of the demixing curve in the liquid state in the Lead – Zinc binary system. We are interested to recalculate the free energies relating on Pb-Zn alloys for several temperatures based on the thermodynamic data collected in the bibliography. This calculation allows us to trace the curve of phase separation from a program after obtaining the mole fractions corresponding to the common tangent to the curve of the free energy with two minima at different temperatures. To do this, we used the Matlab 7.1 as the programming language and the Redlich-Kister polynomial as a mathematical model of development. The results obtained are very satisfactory by comparing them with those of the bibliography.

scholarly journals Agrometeorological analysis of the soybean potentiality in an Amazonian environment

2019 ◽  
Vol 49 ◽  
Author(s):  
Marcus José Alves de Lima ◽  
Evandro Chaves de Oliveira ◽  
Leila Sobral Sampaio ◽  
Clyde William Fraisse ◽  
Paulo Jorge de Oliveira Ponte de Souza
Keyword(s):  
Cropping System ◽  
Climatic Data ◽  
Production Environment ◽  
Soybean Yield ◽  
Local Climate ◽  
Crop Models ◽  
Sowing Dates ◽  
Attainable Yield ◽  
Moisture Conditions ◽  
Soil Climate

ABSTRACT The use of crop models that integrate soil, climate, cultivar and management information may broaden the understanding of the interactions between soybean cropping system and local climate variability. This study aimed to analyze the potentiality of soybean in an Amazonian production environment, as well as to determine an optimal sowing window via agrometeorological modeling. A crop model was programmed to simulate the soybean yield for 18 sowing dates, obtained along 33 years of climatic data, under attainable and potential conditions. The simulated potential of soybean yield ranged from 3,785 kg ha-1 to 5,114 kg ha-1, owing to the local energy availability, whereas the average attainable yield ranged from 557 kg ha-1 to 4,700 kg ha-1, mainly because of the soil moisture conditions. The smallest difference between the potential and attainable yields was observed in the sowing dates from 01-Jan to 15-Feb. For this window, the probability of obtaining yields above 3,500 kg ha-1 was higher than 90 %.

scholarly journals Mineral Composition and Antioxidant Potential in the Common Poppy (Papaver rhoeas L.) Petal Infusions

2020 ◽  
Vol 199 (1) ◽  
pp. 371-381
Author(s):  
Janda Katarzyna ◽  
Jakubczyk Karolina ◽  
Kupnicka Patrycja ◽  
Bosiacki Mateusz ◽  
Gutowska Izabela
Keyword(s):  
Vitamin C ◽  
Mineral Content ◽  
Antioxidant Potential ◽  
Effect Of Temperature ◽  
Total Polyphenol ◽  
Spectrophotometric Methods ◽  
Inflammatory Conditions ◽  
Different Temperatures ◽  
The Common ◽  
Increasing Temperature

AbstractThe flowers of the common poppy are used for medicinal purposes, both internally and externally. They are reported to have antispasmodic and antitussive properties, to alleviate inflammatory conditions and soothe anxiety-related digestive problems. The aim of the study was to determine the antioxidant potential and the content of vitamin C, polyphenols, and minerals in infusions made from the petals of the common poppy at different temperatures. The infusions were made at various temperatures (25 °C, 70 °C, 80 °C, and 90 °C). The antioxidant potential and the content of polyphenols and vitamin C were determined by spectrophotometric methods. The mineral content was determined using the ICP-OES method. The total polyphenol content ranged from 135.2 to 137.24 ppm and that of vitamin C—from 15.47 to 15.78 mg/100 mL. The temperature of the water used to make the infusions did not appear to have a significant effect on these parameters. The temperature did, however, significantly affect the antioxidant potential of the infusions—the highest antioxidant activity (71.21% DPPH inhibition) was observed in the infusion prepared using water at 80 °C. The infusions included in the study contained a number of minerals. No significant effect of temperature was found for the content of K, Zn, Cu, Fe, and Ni in the infusions. On the other hand, the content of Ca in the infusions was significantly correlated with the increasing temperature of the water. It was concluded that poppy petal infusions may serve as a valuable dietary supplement, providing antioxidants and minerals required by the human body to function properly.

scholarly journals Computational Inference of Selection Underlying the Evolution of the Novel Coronavirus, Severe Acute Respiratory Syndrome Coronavirus 2

2020 ◽  
Vol 94 (12) ◽  
Author(s):  
Rachele Cagliani ◽  
Diego Forni ◽  
Mario Clerici ◽  
Manuela Sironi
Keyword(s):  
Severe Acute Respiratory Syndrome ◽  
Positive Selection ◽  
Common Ancestor ◽  
Purifying Selection ◽  
Population Variation ◽  
Binding Motif ◽  
The Novel ◽  
Species Barrier ◽  
The Common ◽  
Novel Coronavirus

ABSTRACT The novel coronavirus severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that recently emerged in China is thought to have a bat origin, as its closest known relative (BatCoV RaTG13) was described previously in horseshoe bats. We analyzed the selective events that accompanied the divergence of SARS-CoV-2 from BatCoV RaTG13. To this end, we applied a population genetics-phylogenetics approach, which leverages within-population variation and divergence from an outgroup. Results indicated that most sites in the viral open reading frames (ORFs) evolved under conditions of strong to moderate purifying selection. The most highly constrained sequences corresponded to some nonstructural proteins (nsps) and to the M protein. Conversely, nsp1 and accessory ORFs, particularly ORF8, had a nonnegligible proportion of codons evolving under conditions of very weak purifying selection or close to selective neutrality. Overall, limited evidence of positive selection was detected. The 6 bona fide positively selected sites were located in the N protein, in ORF8, and in nsp1. A signal of positive selection was also detected in the receptor-binding motif (RBM) of the spike protein but most likely resulted from a recombination event that involved the BatCoV RaTG13 sequence. In line with previous data, we suggest that the common ancestor of SARS-CoV-2 and BatCoV RaTG13 encoded/encodes an RBM similar to that observed in SARS-CoV-2 itself and in some pangolin viruses. It is presently unknown whether the common ancestor still exists and, if so, which animals it infects. Our data, however, indicate that divergence of SARS-CoV-2 from BatCoV RaTG13 was accompanied by limited episodes of positive selection, suggesting that the common ancestor of the two viruses was poised for human infection. IMPORTANCE Coronaviruses are dangerous zoonotic pathogens; in the last 2 decades, three coronaviruses have crossed the species barrier and caused human epidemics. One of these is the recently emerged SARS-CoV-2. We investigated how, since its divergence from a closely related bat virus, natural selection shaped the genome of SARS-CoV-2. We found that distinct coding regions in the SARS-CoV-2 genome evolved under conditions of different degrees of constraint and are consequently more or less prone to tolerate amino acid substitutions. In practical terms, the level of constraint provides indications about which proteins/protein regions are better suited as possible targets for the development of antivirals or vaccines. We also detected limited signals of positive selection in three viral ORFs. However, we warn that, in the absence of knowledge about the chain of events that determined the human spillover, these signals should not be necessarily interpreted as evidence of an adaptation to our species.

Biochemical genetics and recognition of a western stock of the common gemfish, Rexea solandri (Scombroidea : Gempylidae), in Australia

1997 ◽  
Vol 48 (2) ◽  
pp. 103 ◽  
Author(s):  
Donald J. Colgan ◽  
John R. Paxton
Keyword(s):  
Restriction Fragment ◽  
Protein Electrophoresis ◽  
Fish Stock ◽  
Stock Structure ◽  
Muscle Tissues ◽  
Restriction Fragment Polymorphism ◽  
The Common ◽  
Reduced Activity ◽  
Western Australian

Protein electrophoresis and analysis of restriction fragment polymorphism in mitochondrial DNA (mtDNA) provided information on population/stock structure of Rexea solandri. Two distinct Australian stocks are evident, with one (AAT-2) of 36 enzymatic loci and all 11 mtDNA digestion profiles showing highly significant differences between eastern and southern/western Australian specimens. The split is at the western end of Bass Strait, with limited mixing off western Tasmania. No external characters were found that would allow determination of the provenance of an individual fish. Stock distinction between eastern Australian and New Zealand fish is less clear; some differences, usually statistically non-significant, in genetic frequencies were found and some rare allozymic or restriction fragment variants were found in one or other but not both regions. Estimates of gene flow suggest that only tens of individuals per generation migrate between the regions. In an experiment on tissue deterioration, after six days of exposure out of doors, significant amounts of intact mtDNA were present in all tissues, and all fragments of the HINF 1 phenotype were clearly scorable. Of 19 enzymes tested, only three showed reduced activity on Day 6. Gonad and muscle tissues were more resistant to degradation than was liver tissue.

Temperature optima for growth and photosynthetic processes in Trebouxia erici isolated from an Antarctic lichen and cultivated in a temperature gradient

2017 ◽  
Vol 7 (1) ◽  
pp. 34-44 ◽  
Author(s):  
Timm Bayer ◽  
Nıevas Vıals Alba
Keyword(s):  
Chlorophyll Fluorescence ◽  
Natural Populations ◽  
Effective Quantum Yield ◽  
Ps Ii ◽  
Chlorophyll Fluorescence Parameters ◽  
Different Temperatures ◽  
Chlorophyll Production ◽  
Time Courses ◽  
Temperature Optima

The temperature optimum for photosynthesis and growth of natural populations of Trebouxia erici isolated from an Antarctic lichen (Usnea antarctica) was determined using a long-term cultivation (26 days) at different temperatures. Several chlorophyll fluorescence parameters were used in T. erici cultivated in a liquid medium to assess the effect of cultivation temperature (0, 10, 20 and 30oC). Analysis of time courses of the capacity of photosynthetic processes in PS II (FV/FM), effective quantum yield of photosystem II (FPSII), relative fluorescence decline ratio (RFd), and quenching of background chlorophyll fluorescence (qF0) revealed that optimum temperature is between 10 to 20°C. Biomass production evaluated as a total chlorophyll production after 26 days of cultivation was maximal at 20°C. The results are discussed in relation to the data reported by other literature sources for Trebouxia sp. and other algae isolated from chlorolichens.

Observations on the Simulium neavei complex at Amani in Tanganyika.

1960 ◽  
Vol 51 (1) ◽  
pp. 95-113 ◽  
Author(s):  
D. J. Lewis
Keyword(s):  
Short Distance ◽  
Drainage System ◽  
Follicular Epithelium ◽  
Wing Size ◽  
Lower Altitude ◽  
Local Climate ◽  
Before And After ◽  
History Of ◽  
Efficient Vector ◽  
The Common

The paper deals with two members of the Simulium neavi Eoub. complex found at Amani in the forest of the Usambara Mountains, Tanganyika Territory. They have already been described but are at present termed the Amani unhanded and banded forms, scientific names being witheld until the taxonomy of the whole complex is better understood.Some methods of study are described.Pupae of the unhanded form constituted a large proportion of the total number found on the common local crab, Potamon (Potamonautes) lirrangensis Eathbun, which amounted to roughly one pupa to seven crabs. This form predominated in the lower and more open parts of the drainage system examined. The adults were not seen to bite man. This and the banded form were found at a much lower altitude than any hitherto reported for the complex, probably owing to the particular nature of the local climate. Neither form was abundant.The larvae and pupae of the banded form, like the unhanded one, live externally on the crabs. The variability of wing size of the banded form is described. Observations were made on the internal anatomy of the adult with special reference to the ovaries in which the follicular relics are usually very large, indicating that the female probably bites soon after laying eggs. As in S. damnosum Theo. there is an easily recognisable class of old flies with clear Malpighian tubes. Nulliparous and parous flies have rather different biting cycles. The banded form bit man readily but only about five were taken per hour in good catching places and far fewer elsewhere.Human onchorcerciasis has been reported from Amani but is not known to do any harm there. The existence of the disease in the presence of rather small numbers of Simuliids is of interest in relation to a belief that S. neavei is a more efficient vector of onchocerciasis than is S. damnosum. Out of 359 banded females dissected 41·2 per cent, were parous and 12·8 per cent, of these were infected with nematodes, at least some of which were not Onchocerca volvulus.Taxonomy, the ovarioles and the Simuliid-crab association are discussed. The formation of the large follicular relics of the banded form is considered in relation to the history of the follicular epithelium before and after ovulation. The crab association is regarded as commensalism-, and it is suggested that the crabs benefit the Simuliids by carrying them a short distance to a suitable current and that they thus enable them to live in fast rivers and so extend their range.

Local climate controls among-population variation in germination patterns in two Erica species across western Iberia

2018 ◽  
Vol 28 (2) ◽  
pp. 112-122 ◽  
Author(s):  
Daniel Chamorro ◽  
Belén Luna ◽  
José M. Moreno
Keyword(s):  
Climate Change ◽  
Heat Shock ◽  
Seed Dormancy ◽  
Climate Change Impacts ◽  
Population Variation ◽  
Local Climate ◽  
Climate Gradients ◽  
Germination Response ◽  
Key Factor ◽  
Response To Temperature

AbstractIn seasonal climates, germination timing is mainly controlled by temperature, especially in species with physiological seed dormancy. The germination response to temperature may, however, vary among populations across the distribution range of species. Understanding how populations along climate gradients vary in their sensitivity to temperature is important for determining their vulnerability to climate variability and change. Here, we investigated the germination response of two Erica species with physiological seed dormancy (E. australis and E. umbellata) to changes in temperature throughout the seasons (simulated autumn through to spring) and to the local climate in six localities across a latitudinal gradient in western Iberia. Effects were studied with and without exposing the seeds to a heat shock. The local climate of seed provenance emerged as a key factor in modifying the germination sensitivity to germination temperature and their variation through the seasons. Although each species showed idiosyncratic germination responses to temperature treatments and across the gradient, germination of both species was sensitive to warmer temperatures and to a heat shock. Both showed similar seasonal germination patterns: as we moved from south to north, populations tended to have a larger germination peak in spring, which was greater at colder temperatures. We conclude that rising temperatures associated with climate change will affect these species, particularly at their northern ranges, where many seeds will remain dormant during warmer winters. Arguably, models aiming at assessing climate change impacts in these species need to include such variability across latitude.

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