The parasitic ascomycete Mniaecia jungermanniae induces the formation of giant perichaetia and apogamous sporophytes in leafy liverworts

2006 ◽  
Vol 84 (3) ◽  
pp. 384-392 ◽  
Author(s):  
Silvia Pressel ◽  
Jeffrey G Duckett
Keyword(s):  
Growth Regulators ◽  
Parasitic Fungus ◽  
Symbiotic Association ◽  
First Report ◽  
Perfect Stage ◽  
Local Depression ◽  
In The Wild ◽  
Organic Nutrients

To test the hypothesis that the apothecia of Mniaecia jungermanniae (Nees ex Fr.) Boud. growing on stems of the liverwort Cephalozia bicuspidata (L.) Dumort. might be the perfect stage of an ascomycete fungus forming a symbiotic association with swollen rhizoids in a liverwort, we grew both axenically and resynthesized the association. Contrary to our expectation, Mniaecia remained extracellular, but induced, on Cephalozia , the formation of giant perichaetia containing supernumerary archegonia followed by parthenogenetic and apogamous sporophytes. This is the first report of these latter two features in liverworts. By analogy with apogamy and apospory in mosses and pteridophytes that are induced by media supplemented with organic nutrients and growth regulators, we suggest that the abnormal structures in Cephalozia resulted from substances produced by Mniaecia. Giant perichaetia and abnormal perianths were also observed on wild colonies of Cephalozia, Diplophyllum , and Scapania heavily infected with Mniaecia. Apart from local depression of perianth formation in the wild, this parasitic fungus appears to cause no long-term damage to its hosts.

Somatic Embryogenesis and In vitro Plant Regeneration in Vigna trilobata (L.) Verd. - A Potential Pasture Legume

1970 ◽  
Vol 19 (1) ◽  
pp. 89-99
Author(s):  
K. Choudhary ◽  
M. Singh ◽  
M. S. Rathore ◽  
N. S. Shekhawat
Keyword(s):  
Somatic Embryogenesis ◽  
Growth Regulators ◽  
Somatic Embryos ◽  
Basal Medium ◽  
Long Term Study ◽  
Continuous Application ◽  
First Time ◽  
Pasture Legume

This long term study demonstrates for the first time that it is possible to propagate embryogenic Vigna trilobata and to subsequently initiate the differentiation of embryos into complete plantlets. Initiation of callus was possible on 2,4-D. Somatic embryos differentiated on modified MS basal nutrient medium with 1.0 mg/l  of 2,4-D and 0.5 mg/l  of Kn. Sustained cell division resulted in globular and heart shape stages of somatic embryos. Transfer of embryos on to a fresh modified MS basal medium with 0.5 mg/l of Kn and 0.5 mg/l of GA3 helped them to attain maturation and germination. However, the propagation of cells, as well as the differentiation of embryos, were inhibited by a continuous application of these growth regulators. For this reason, a long period on medium lacking these growth regulators was necessary before the differentiation of embryos occurred again. The consequences for improving the propagation of embryogenic cultures in Vigna species are discussed. Key words: Pasture  legume, Vigna trilobata, Globular, Heart shape, somatic embryogenesis D.O.I. 10.3329/ptcb.v19i1.4990 Plant Tissue Cult. & Biotech. 19(1): 89-99, 2009 (June)

An ER–Golgi Tethering Factor SLOH4/MIP3 Is Involved in Long-term Heat Tolerance of Arabidopsis

2020 ◽  
Author(s):  
Kazuho Isono ◽  
Ryo Tsukimoto ◽  
Satoshi Iuchi ◽  
Akihisa Shinozawa ◽  
Izumi Yotsui ◽  
...  
Keyword(s):  
Heat Stress ◽  
Heat Tolerance ◽  
Secretory Proteins ◽  
Wild Type ◽  
Additional Function ◽  
Transcript Levels ◽  
Unfolded Protein ◽  
In The Wild ◽  
Protein Response

Abstract Plants are often exposed not only to short-term (S-) heat stress but also to diurnal long-term (L-) heat stress over several consecutive days. To reveal the mechanisms underlying L-heat stress tolerance, we here used a forward genetic screening for sensitive to long-term heat (sloh) mutants and isolated sloh4. The mutant was hypersensitive to L- but not S-heat stress. The causal gene of sloh4 was identical to MIP3 encoding a member of the MAIGO2 (MAG2) tethering complex, which is composed of the MAG2, MIP1, MIP2, and MIP3 subunits and is localized at the endoplasmic reticulum (ER) membrane. Although sloh4/mip3 was hypersensitive to L-heat stress, the sensitivity of the mag2-3 and mip1–1 mutants was similar to that of the wild type. Under L-heat stress, the ER stress and the following unfolded protein response (UPR) were more pronounced in sloh4 than in the wild type. Transcript levels of bZIP60-regulated UPR genes were strongly increased in sloh4 under L-heat stress. Two processes known to be mediated by INOSITOL REQUIRING ENZYME1 (IRE1)—accumulation of the spliced bZIP60 transcript and a decrease in the transcript levels of PR4 and PRX34, encoding secretory proteins—were observed in sloh4 in response to L-heat stress. These findings suggest that misfolded proteins generated in sloh4 under L-heat stress may be recognized by IRE1 but not bZIP28, resulting in initiation of the UPR via activated bZIP60. Therefore, it would be possible that only MIP3 in MAG2 complex has an additional function in L-heat tolerance, which is not related to the ER–Golgi vesicle tethering.

scholarly journals Non-breeding feather concentrations of testosterone, corticosterone and cortisol are associated with subsequent survival in wild house sparrows

2011 ◽  
Vol 279 (1733) ◽  
pp. 1560-1566 ◽  
Author(s):  
Lee Koren ◽  
Shinichi Nakagawa ◽  
Terry Burke ◽  
Kiran K. Soma ◽  
Katherine E. Wynne-Edwards ◽  
...  
Keyword(s):  
Stress Hormones ◽  
Passer Domesticus ◽  
House Sparrows ◽  
Long Term Study ◽  
Darwinian Fitness ◽  
Liquid Chromatography Tandem Mass ◽  
In The Wild ◽  
The Subject ◽  
As Stress

Potential mechanistic mediators of Darwinian fitness, such as stress hormones or sex hormones, have been the focus of many studies. An inverse relationship between fitness and stress or sex hormone concentrations has been widely assumed, although empirical evidence is scarce. Feathers gradually accumulate hormones during their growth and provide a novel way to measure hormone concentrations integrated over time. Using liquid chromatography–tandem mass spectrometry, we measured testosterone, corticosterone and cortisol in the feathers of house sparrows ( Passer domesticus ) in a wild population which is the subject of a long-term study. Although corticosterone is considered the dominant avian glucocorticoid, we unambiguously identified cortisol in feathers. In addition, we found that feathers grown during the post-nuptial moult in autumn contained testosterone, corticosterone and cortisol levels that were significantly higher in birds that subsequently died over the following winter than in birds that survived. Thus, feather steroids are candidate prospective biomarkers to predict the future survival of individuals in the wild.

scholarly journals Population genetics of the coral Acropora millepora: Towards a genomic predictor of bleaching

2019 ◽  
Author(s):  
Zachary L. Fuller ◽  
Veronique J.L. Mocellin ◽  
Luke Morris ◽  
Neal Cantin ◽  
Jihanne Shepherd ◽  
...  
Keyword(s):  
Genome Wide Association Study ◽  
Balancing Selection ◽  
Genome Wide Association ◽  
Conservation Strategies ◽  
Genome Sequences ◽  
Acropora Millepora ◽  
Genome Wide ◽  
A Genome ◽  
In The Wild

AbstractAlthough reef-building corals are rapidly declining worldwide, responses to bleaching vary both within and among species. Because these inter-individual differences are partly heritable, they should in principle be predictable from genomic data. Towards that goal, we generated a chromosome-scale genome assembly for the coral Acropora millepora. We then obtained whole genome sequences for 237 phenotyped samples collected at 12 reefs distributed along the Great Barrier Reef, among which we inferred very little population structure. Scanning the genome for evidence of local adaptation, we detected signatures of long-term balancing selection in the heat-shock co-chaperone sacsin. We further used 213 of the samples to conduct a genome-wide association study of visual bleaching score, incorporating the polygenic score derived from it into a predictive model for bleaching in the wild. These results set the stage for the use of genomics-based approaches in conservation strategies.

scholarly journals Orchid Reintroduction Based on Seed Germination-Promoting Mycorrhizal Fungi Derived From Protocorms or Seedlings

2021 ◽  
Vol 12 ◽  
Author(s):  
Da-Ke Zhao ◽  
Marc-André Selosse ◽  
Limin Wu ◽  
Yan Luo ◽  
Shi-Cheng Shao ◽  
...  
Keyword(s):  
Seed Germination ◽  
Mycorrhizal Fungi ◽  
Essential Element ◽  
Ecological Factors ◽  
New Approach ◽  
Practical Procedure ◽  
In The Wild ◽  
Orchid Mycorrhizal Fungi ◽  
Ecological Specificity

Orchids are among the most endangered in the plant kingdom. Lack of endosperm in their seeds renders orchids to depend on nutrients provided by orchid mycorrhizal fungi (OMF) for seed germination and seedling formation in the wild. OMF that parasitize in germination seeds is an essential element for orchid seedling formation, which can also help orchid reintroduction. Considering the limitations of the previous orchid reintroduction technology based on seed germination-promoting OMF (sgOMF) sourced from orchid roots, an innovative approach is proposed here in which orchid seeds are directly co-sown with sgOMF carrying ecological specificity from protocorms/seedlings. Based on this principle, an integrative and practical procedure concerning related ecological factors is further raised for re-constructing long-term and self-sustained orchid populations. We believe that this new approach will benefit the reintroduction of endangered orchids in nature.

scholarly journals A nonlinear relationship between prediction errors and learning rates in human reinforcement learning

2019 ◽  
Author(s):  
Erdem Pulcu
Keyword(s):  
Reinforcement Learning ◽  
Nonlinear Relationship ◽  
Prediction Errors ◽  
Learning Rates ◽  
The Face ◽  
In The Wild ◽  
Actual Outcome ◽  
Update Rules ◽  
Different Sources

AbstractWe are living in a dynamic world in which stochastic relationships between cues and outcome events create different sources of uncertainty1 (e.g. the fact that not all grey clouds bring rain). Living in an uncertain world continuously probes learning systems in the brain, guiding agents to make better decisions. This is a type of value-based decision-making which is very important for survival in the wild and long-term evolutionary fitness. Consequently, reinforcement learning (RL) models describing cognitive/computational processes underlying learning-based adaptations have been pivotal in behavioural2,3 and neural sciences4–6, as well as machine learning7,8. This paper demonstrates the suitability of novel update rules for RL, based on a nonlinear relationship between prediction errors (i.e. difference between the agent’s expectation and the actual outcome) and learning rates (i.e. a coefficient with which agents update their beliefs about the environment), that can account for learning-based adaptations in the face of environmental uncertainty. These models illustrate how learners can flexibly adapt to dynamically changing environments.

Senescence in the wild: Insights from a long-term study on Seychelles warblers

2015 ◽  
Vol 71 ◽  
pp. 69-79 ◽  
Author(s):  
Martijn Hammers ◽  
Sjouke A. Kingma ◽  
Kat Bebbington ◽  
Janske van de Crommenacker ◽  
Lewis G. Spurgin ◽  
...  
Keyword(s):  
Term Study ◽  
Long Term Study ◽  
In The Wild

First report on the efficacy of l-alanine-based in situ-forming implants for the long-term parenteral delivery of drugs

2005 ◽  
Vol 108 (2-3) ◽  
pp. 433-441 ◽  
Author(s):  
François Plourde ◽  
Aude Motulsky ◽  
Anne-Claude Couffin-Hoarau ◽  
Didier Hoarau ◽  
Huy Ong ◽  
...  
Keyword(s):  
First Report ◽  
Parenteral Delivery ◽  
In Situ Forming ◽  
In Situ Forming Implants

Distinct rhizomicrobiota assemblages and plant performance in lettuce grown in soils with different agricultural management histories

2021 ◽  
Vol 97 (4) ◽  
Author(s):  
Doreen Babin ◽  
Loreen Sommermann ◽  
Soumitra Paul Chowdhury ◽  
Jan H Behr ◽  
Martin Sandmann ◽  
...  
Keyword(s):  
Growth Regulators ◽  
Stress Responses ◽  
Crop Production ◽  
Agricultural Management ◽  
Plant Performance ◽  
16S Rrna Genes ◽  
Rrna Genes ◽  
Soil Microbiota ◽  
Sustainable Crop Production

ABSTRACT A better understanding of factors shaping the rhizosphere microbiota is important for sustainable crop production. We hypothesized that the effect of agricultural management on the soil microbiota is reflected in the assemblage of the rhizosphere microbiota with implications for plant performance. We designed a growth chamber experiment growing the model plant lettuce under controlled conditions in soils of a long-term field experiment with contrasting histories of tillage (mouldboard plough vs cultivator tillage), fertilization intensity (intensive standard nitrogen (N) + pesticides/growth regulators vs extensive reduced N without fungicides/growth regulators), and last standing field crop (rapeseed vs winter wheat). High-throughput sequencing of bacterial and archaeal 16S rRNA genes and fungal ITS2 regions amplified from total community DNA showed that these factors shaped the soil and rhizosphere microbiota of lettuce, however, to different extents among the microbial domains. Pseudomonas and Olpidium were identified as major indicators for agricultural management in the rhizosphere of lettuce. Long-term extensive fertilization history of soils resulted in higher lettuce growth and increased expression of genes involved in plant stress responses compared to intensive fertilization. Our work adds to the increasing knowledge on how soil microbiota can be manipulated by agricultural management practices which could be harnessed for sustainable crop production.

scholarly journals Propagation of Threatened Nepenthes khasiana: Methods and Precautions

2015 ◽  
Vol 7 (3) ◽  
pp. 313-315
Author(s):  
Jibankumar S. KHURAIJAM ◽  
Rup K. ROY
Keyword(s):  
Plant Species ◽  
Threatened Species ◽  
Ex Situ Conservation ◽  
Ex Situ ◽  
In The Wild ◽  
Propagation Technique ◽  
Subsequent Propagation ◽  
Nepenthes Khasiana

Ex-situ conservation is an important key in the management of rare, endangered and threatened (RET) plant species and its effectiveness depends on several factors. Maintenance of viable germplasm and its subsequent propagation plays an important role in long term conservation of many RET species. Nepenthes khasiana is a rare and gravely threatened species in the wild due to over-collection and other threats. The species needs urgent in-situ and ex-situ conservation. Development of easy to propagate techniques would pave faster multiplication for its use of educational, medicinal and horticultural purpose. In the present paper, successful propagation technique of Nepenthes khasiana through seeds is demonstrated along with detailed information on precautions to be taken during the adoption of the techniques.

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