Genetics of Gibberella fujikuroi. III. Significance of heterokaryosis in naturally occurring corn isolates

1983 ◽  
Vol 61 (12) ◽  
pp. 3320-3325 ◽  
Author(s):  
Gurmel S. Sidhu
Keyword(s):  
Gibberella Fujikuroi ◽  
Growth Stages ◽  
Corn Plant ◽  
Stalk Rot ◽  
Naturally Occurring ◽  
Fungal Organisms ◽  
Colony Color ◽  
The Subject ◽  
Different Growth Stages

Among the stalk rot fungal organisms, Gibberella fujikuroi (Saw.) Wn. (conidial anamorph Fusarium moniliforme Sheld.) was abundant in naturally infected com plants. Numerous phenotypically different isolates of F. moniliforme were recovered from the host. Some of these isolates formed heterokaryons more frequently in a given stage of plant growth. Frequently occurring heterokaryons were termed major and became the subject of this report. The component homokaryons exhibited differences in colony color, texture, growth rate, and sporulation. Based on these differences, ratios of two homokaryons recovered from a single representative of each of the four major heterokaryons were found to be balanced. Representative natural and laboratory-induced heterokaryons were compared for stability and balance of nuclear ratios on MM and SRM (stalk residue medium). Different heterokaryons predominated at different growth stages of the corn plant indicating preferential adaptation. Possible role of these heterokaryons in generating and maintaining natural variability was evaluated.

Genetics of Gibberella fujikuroi. II. Natural occurrence and significance of heterokaryosis in sorghum isolates

1983 ◽  
Vol 61 (12) ◽  
pp. 3314-3319 ◽  
Author(s):  
Gurmel S. Sidhu
Keyword(s):  
Fusarium Moniliforme ◽  
Growth Stage ◽  
Gibberella Fujikuroi ◽  
Growth Stages ◽  
Natural Occurrence ◽  
Stalk Rot ◽  
Colony Color ◽  
Different Growth Stages ◽  
Natural Media

Of all the stalk rot fungi, Gibberella fujikuroi (Sawada) Wollenw. (anamorph stage Fusarium moniliforme Sheld.) was most frequently isolated from naturally infected, symptomless sorghum plants. Phenotypically distinct isolates of G. fujikuroi were recovered. This variability is ascribed to heterokaryosis. The homokaryotic components of the most frequently recovered heterokaryons found at a given growth stage were identified on the basis of colony color, texture, growth rate, and sporulation. Nuclear ratios were determined to confirm the presence and stability of heterokaryons. Natural and laboratory-induced heterokaryons were compared on synthetic and natural media, prepared from plant tissue, for stability and other attributes. The occurrence of different heterokaryons at different growth stages suggests genetic adaptation and a possible role of heterokaryosis in generating and maintaining natural variability in this fungus.

scholarly journals Alfalfa (Medicago sativaL.) shoot saponins: identification and bio-activity by the assessment of aphid feeding

2010 ◽  
Vol 105 (1) ◽  
pp. 62-70 ◽  
Author(s):  
H. Mazahery-Laghab ◽  
B. Yazdi-Samadi ◽  
M. Bagheri ◽  
A. R. Bagheri
Keyword(s):  
Plant Development ◽  
Insect Pests ◽  
Biological Effects ◽  
Biological Role ◽  
Growth Stages ◽  
Oral Toxicity ◽  
Medicagenic Acid ◽  
Significant Difference ◽  
Different Growth Stages

Biochemical components in alfalfa (Medicago sativaL.), such as saponins, can act as protecting factors against bio-stresses. Saponins are also antifeedants and show oral toxicity towards higher and lower animals. Changes in saponins, such as variation in the carbon skeleton, or hydrolysis of saponin glycosides and other conjugates, may change their biological effects. The aims of this research were to study saponin variation in different growth stages of alfalfa and to investigate the biological role of saponins in the spotted alfalfa aphid,Therioaphis maculata. Saponins from alfalfa shoots in different growth stages were extracted, chemically purified and analysed by TLC. Specific saponins such as soyasaponin1 from root and shoot and two bisdesmosides of medicagenic acid, one from shoot and another from root tissues, were identified using reference compounds allowing changes in saponin composition during plant development in different shoot tissues of alfalfa to be assessed. The response of the alfalfa aphid to feeding on alfalfa in different growth stages was studied. No significant difference in the survival of aphids, from neonate to adult, was observed, but due to the antibiotic effects of saponins, two differences were found in the onset of nymph production and cumulative nymph production. The results show that the saponin composition in alfalfa changes with plant development and this, in turn, can often negatively affect the development of specific insect pests such as the spotted alfalfa aphid, suggesting a possible biological role of alfalfa saponins.

scholarly journals Rhythmic Control of The Plant-Microbiome Holobiont

2020 ◽  
Author(s):  
Tao Lu ◽  
Zhenyan Zhang ◽  
Yan Li ◽  
Qi Zhang ◽  
Liwei Sun ◽  
...  
Keyword(s):  
Microbial Community ◽  
Circadian Clock ◽  
Root Exudates ◽  
Root Exudation ◽  
Biological Clock ◽  
Diurnal Rhythms ◽  
Growth Stages ◽  
Plant Host ◽  
Different Growth Stages

Abstract Background: Many physiological and metabolic processes in plants are modulated by a circadian clock. Rhizospheric microorganisms fed by root exudates provide beneficial functions to their plant host. The intricate connection between the circadian clock and the rhizospheric microbial community remains poorly understood. Results: We investigated the role of the Arabidopsis circadian clock in shaping the rhizospheric microbial community using wild-type plants and clock mutants (cca1-1 and toc1-101). We performed transcriptomic and metabolomic analyses and sequenced amplicons of the 16S ribosomal RNA gene to characterize gene transcription, root exudation and the bacterial communities, respectively, throughout the day (24 h). Deficiencies of the central circadian clock led to abnormal diurnal rhythms for thousands of expressed genes and dozens of root exudates. Bacterial community failed to follow obvious patterns in the 24-h period, and lack of coordination with plant growth in the clock mutants. Conclusions: Our findings suggested that the biological clock was an important force that drove plants to adjust their rhizospheric microbiomes for adapting to different growth stages.

Bdellovibrio sp. – A Predator under Groundwater Conditions? A Short Communication

1991 ◽  
Vol 24 (2) ◽  
pp. 321-324 ◽  
Author(s):  
Z. Filip ◽  
P. Schmelz ◽  
R. Smed-Hildmann
Keyword(s):  
Limiting Factors ◽  
Growth Stages ◽  
Ph Values ◽  
Transmission Electron ◽  
Groundwater Samples ◽  
Collection Strain ◽  
The Individual ◽  
Pristine Aquifer ◽  
Different Growth Stages

The role of Bdellovibrio sp. in affecting the development of gram-negative bacteria under natural conditions is not yet completely understood. In our investigations, no predatory activity was observed in groundwater samples from a deep pristine aquifer. As limiting factors, temperature and pH may play a role. Their respective ambient values were T=10° C and pH 6.07. In laboratory experiments using a collection strain of B.bacteriovorus and a wild type from sewage, appreciable numbers of plaques appeared at a minimum temperature of 18° C. The optimum temperature at which more than 100 plaques were pounted was 26° C and 30° C. At pH values lower than 6 no plaques were formed but more than 100 were observed at pH 7, 8 and 9. From the individual plaques, different growth stages of Bdellovibrio sp. have been identified using a transmission electron microscope.

Role of Vocal Tract Morphology in Speech Development

2004 ◽  
Vol 47 (5) ◽  
pp. 1059-1080 ◽  
Author(s):  
Lucie Ménard ◽  
Jean-Luc Schwartz ◽  
Louis-Jean Boë
Keyword(s):  
Vocal Tract ◽  
Speech Development ◽  
Growth Stages ◽  
Physical Factors ◽  
Acoustic Model ◽  
Phonological Representations ◽  
Vocal Apparatus ◽  
Specific Configuration ◽  
Different Growth Stages

The development of speech from infancy to adulthood results from the interaction of neurocognitive factors, by which phonological representations and motor control abilities are gradually acquired, and physical factors, involving the complex changes in the morphology of the articulatory system. In this article, an articulatory-to-acoustic model, integrating nonuniform vocal tract growth, is used to describe the effect of morphology in the acoustic and perceptual domains. While simulating mature control abilities of the articulators (freezing neurocognitive factors), the size and shape of the vocal apparatus are varied, to represent typical values of speakers from birth to adulthood. The results show that anatomy does not prevent even the youngest speaker from producing vowels perceived as the 10 French oral vowels /i y u e ø o ε œ a/. However, the specific configuration of the vocal tract for the newborn seems to favor the production of those vowels perceived as low and front. An examination of the acoustic effects of articulatory variation for different growth stages led to the proposed variable sensorimotor maps for newbornlike, childlike, and adultlike vocal tracts. These maps could be used by transcribers of infant speech, to complete existing systems and to provide some hints about underlying articulatory gestures recruited during growth to reach perceptual vowel targets in French.

scholarly journals Calcium Plays a Double-Edged Role in Modulating Cadmium Uptake and Translocation in Rice

2020 ◽  
Vol 21 (21) ◽  
pp. 8058
Author(s):  
Shuo Zhang ◽  
Qi Li ◽  
Muhammad Mudassir Nazir ◽  
Shafaqat Ali ◽  
Younan Ouyang ◽  
...  
Keyword(s):  
Agricultural Production ◽  
Essential Element ◽  
Growth Period ◽  
Growth Stages ◽  
Cd Uptake ◽  
Rice Grains ◽  
Cd Contamination ◽  
Cd Translocation ◽  
Different Growth Stages

Cadmium (Cd) contamination in soils poses great risks to both agricultural production and human health. Calcium (Ca) is an essential element playing a significant role in protecting plants against Cd toxicity. However, how Ca affects Cd uptake and translocation in rice is still not fully elucidated. In this study, the regulatory role of Ca in Cd uptake and upward translocation was investigated in rice at different growth stages. Our results showed that the supplement of 5 mM Ca significantly reduced Cd uptake by rice roots, because of their competition for Ca-permeable channels as an absorption site and Ca-induced downregulation of OsNRAMP1 and OsNRAMP5. However, Ca application facilitated the upward translocation of Cd by both upregulating OsHMA2 to induce xylem loading of Cd and downregulating OsHMA3 to reduce vacuolar sequestration of Cd. Such contrary results suggested a double-edged role of Ca in regulating root Cd uptake and root-to-shoot Cd translocation in rice. Although it increased Cd content in the aboveground vegetative tissues during the whole growth period, the addition of 5 mM Ca eventually decreased Cd content in rice grains at the ripening stage. All these results suggest that Ca-based amendments possess great potential for the production of low-Cd rice grains.

Fine structure and properties of defects in naturally occurring silicates and oxides

1990 ◽  
Vol 48 (4) ◽  
pp. 460-461
Author(s):  
David R. Veblen
Keyword(s):  
Chemical Reactions ◽  
High Resolution Electron Microscopy ◽  
Extended Defects ◽  
Single Chain ◽  
Naturally Occurring ◽  
Resolution Electron ◽  
Fine Structures ◽  
Image Simulations ◽  
Similar Crystal Structure

Extended defects and interfaces control many processes in rock-forming minerals, from chemical reactions to rock deformation. In many cases, it is not the average structure of a defect or interface that is most important, but rather the structure of defect terminations or offsets in an interface. One of the major thrusts of high-resolution electron microscopy in the earth sciences has been to identify the role of defect fine structures in reactions and to determine the structures of such features. This paper will review studies using HREM and image simulations to determine the structures of defects in silicate and oxide minerals and present several examples of the role of defects in mineral chemical reactions. In some cases, the geological occurrence can be used to constrain the diffusional properties of defects.The simplest reactions in minerals involve exsolution (precipitation) of one mineral from another with a similar crystal structure, and pyroxenes (single-chain silicates) provide a good example. Although conventional TEM studies have led to a basic understanding of this sort of phase separation in pyroxenes via spinodal decomposition or nucleation and growth, HREM has provided a much more detailed appreciation of the processes involved.

Top-Down Processing and Visual Reorientation Illusions in a Virtual Reality Environment

2004 ◽  
Vol 63 (3) ◽  
pp. 143-149 ◽  
Author(s):  
Fred W. Mast ◽  
Charles M. Oman
Keyword(s):  
Virtual Reality ◽  
Visual Processing ◽  
Line Length ◽  
Perceptual Cues ◽  
Virtual Reality Environment ◽  
Top Down ◽  
Test Conditions ◽  
The Subject ◽  
Processing Mechanisms

The role of top-down processing on the horizontal-vertical line length illusion was examined by means of an ambiguous room with dual visual verticals. In one of the test conditions, the subjects were cued to one of the two verticals and were instructed to cognitively reassign the apparent vertical to the cued orientation. When they have mentally adjusted their perception, two lines in a plus sign configuration appeared and the subjects had to evaluate which line was longer. The results showed that the line length appeared longer when it was aligned with the direction of the vertical currently perceived by the subject. This study provides a demonstration that top-down processing influences lower level visual processing mechanisms. In another test condition, the subjects had all perceptual cues available and the influence was even stronger.

Cytokinins from terminal buds of Euphoria longana during different growth stages

1997 ◽  
Vol 99 (1) ◽  
pp. 185-189
Author(s):  
Wen-Shaw Chen ◽  
Kuang-Liang Huang ◽  
Hsiao-Ching Yu
Keyword(s):  
Growth Stages ◽  
Terminal Buds ◽  
Different Growth Stages
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