The Teign Gorge is located in the north eastern section of Dartmoor National Park close to the ancient stannary town Chagford and the pretty villages Drewsteignton and Dunsford. The National Trust's Castle Drogo is at the mouth of the gorge.

Teign Gorge 

  

The Teign Gorge is located in the north eastern section of Dartmoor National Park close to the ancient stannary town Chagford and the pretty villages Drewsteignton and Dunsford. The National Trust's Castle Drogo is at the mouth of the gorge. The National

Trust's Dunsford Wood and Steps Bridge are to the east.

We've been walking the Teign Gorge on a regular basis for over seven years now and never tire of its natural beauty. It's widely recognised as being one of the most stunning areas in the National Park. We've positioned the Teign Gorge on Google maps so zoom in on the 'Satellite' setting to see its exact location.

Cut by the River Teign that rises at two sources on Dartmoor's high north plateau, the gorge is a wooded, steep sided valley that runs for miles towards the National Park border.

If you are visiting for the first time, explore the area between Castle Drogo and Fingle Bridge. There's ample parking at both attractions. Follow the Hunter's Path along the northern lip of the gorge and return on the Fisherman's Path that follows the course of the River Teign. The views from the Hunter's Path around Sharp Tor (Teign Gorge/North East Dartmoor) are particularly impressive. You'll see Chagford and the high moors around Hangingstone Hill to the west.

Within the gorge, we'd recommend visiting Castle Drogo, Fingle Bridge with its pub and Sharp Tor. Across the valley from Castle Drogo is the superb Whiddon Deer Park. Cranbrook Castle Hillfort offers immense views of Dartmoor National Park and large areas of Devon. Paths have been opened up on the southern side of the gorge under the name Deer Stalkers Paths.

Given the high number of attractions within the Teign Gorge, plan a weekend break to Chagford to explore the area. There's a top walk along the gorge from Chagford. In Spring and Autumn, it's particularly stunning.

If this is your type of thing, try also the Dart Gorge and Lustleigh Cleave, Tavy Cleave and the wooded valleys around Burrator Reservoir.

In early August 2013, the National Trust and Woodland Trust announced that they had acquired, and were set to restore, a stretch of woodland in the middle of the Teign Gorge between the National Trust's Castle Drogo Estate and the National Trust's woodland around Steps Bridge. This woodland is known as Fingle Woods (National Trust/Woodland Trust). The acquisition means that the entire length of the gorge is now managed by the National Trust and Woodland Trust. A statement from the National Trust explained: 'Together we'll be able to create almost 30 miles (48km) of footpaths for visitors who will be able to see and enjoy the woodlands and get a real feel for the enormity of the place. The woodlands now belong to us jointly and we are ready to start the restoration process for the benefit of wildlife and people over the next 50 years. It also now allows us to manage a 10km long landscape of woodland in the Teign Gorge on Dartmoor'.

Holne,

Mel Pool, Holne, Dartmoor National Park

Wild swimming is popular in Dartmoor National Park. Mel Pool is one of the most beautiful, and remote, places in which you can enjoy it. A stretch of cascades and calm pools of water on the River Dart in the stunning Dart Gorge, it's relatively difficult to get to although nothing too challenging for a fit person.

We've positioned the Mel Pool area on Google maps so zoom in on the 'Satellite' setting to see its location.

The Dart Gorge is an amazing steep-sided gorge cut by the River Dart as it flows from the north moor down to Dartmouth. Mel Tor is a rocky outcrop on the north lip of the gorge. Bench Tor is another rocky outcrop on a spur of land on the south side of the gorge. Between Mel Tor and Bench Tor, all the way down at the bottom of the gorge, is Mel Pool where the Dart bends through particularly wild woodland and runs towards another wild swimming area called Sharrah Pool. Heavily wooded gorge walls tower above you and amplify the sound of water as it flows east.

To visit, follow the road that runs from Ashburton to Holne. Continue past Holne to Venford Reservoir on the edge of the south moor. There are two car parks on either side of the reservoir. Start from the car park to the east. From that car park, walk north west to the corner of the railings that surround the reservoir dam and water works. Drop down to a disused road. This runs round the spur of land on which Bench Tor is located. Follow the disused road for a few minutes and you'll see a track to your left that cuts down through bracken. It runs alongside Venford Brook as it drops to the edge of the River Dart. A path runs east. Follow the river downstream. You'll pass cascades, a waterfall and other pools of water in which you can swim. Somtimes you walk by the river. Sometimes you leave the bank and walk above the river. Mel Pool is located on the bend of the river as marked on the Ordnance Survey Explorer OL28 'Dartmoor' map. There are giant slabs of granite and stretches of calm water.

Note that you can follow the river on foot down to Sharrah Pool. It's very difficult walking on narrow tracks and across slippery rocks. There are some steep climbs and drops so be very careful. Don't try this route if you are not a confident walker or reasonably fit. That said, we've done this with young kids so, in the scheme of things, it's not that difficult. 

tmôr yr afon the river sea dating from the 3800s BC. The Levels were the location of the Glastonbury Lake Village as well as two Lake villages at Meare Lake. Several settlements and hill forts were built on the natural "islands" of slightly raised land, including Brent Knoll and Glastonbury.

The city of Swansea is the largest settlement on the Welsh coast of the Bristol Channel. Other major built-up areas include Barry (including Barry Island), Port Talbot and Llanelli. Smaller resort towns include Porthcawl, Mumbles, Saundersfoot and Tenby. The cities of Cardiff and Newport adjoin the Severn estuary, but lie upstream of the Bristol Channel itself. On the English side, the resort towns of Weston-super-Mare, Burnham-on-Sea, Watchet, Minehead and Ilfracombe are located on the Bristol Channel. Barnstaple and Bideford are sited on estuaries opening onto Bideford Bay, at the westernmost end of the Bristol Channel. Just upstream of the official eastern limit of the Channel, adjoining the Severn estuary, is the city of Bristol, originally established on the River Avon but now with docks on the Severn estuary, which is one of the most important ports in Britain. It gives its name to the Channel, which forms its seaward approach. Bristol Channel floods, 1607
On 30 January 1607 (New style) thousands of people were drowned, houses and villages swept away, farmland inundated and flocks destroyed when a flood hit the shores of the Channel. The devastation was particularly bad on the Welsh side, from Laugharne in Carmarthenshire to above Chepstow on the English border. Cardiff was the most badly affected town. There remain plaques up to 8 ft (2.4 m) above sea level to show how high the waters rose on the sides of the surviving churches. It was commemorated in a contemporary pamphlet "God's warning to the people of England by the great overflowing of the waters or floods."

Love o’ the ground, All healand True Love, Mothers wort and Queen of the Meadows. As for a salve wherewith to anoint the forehead against visits from “Elf or goblin night visitors,

Country Contentments 
STO LEN goods are sweetest when a title is needed for extracts from the “ Cunynge Curiosities” of 10th- to 18th-century writers; books “wherein, thou o Reader (if thou canst but read) art sure to finde abundance and plenty of matters most dainty.” Gervase Markham, the author of 16th-century Country Contentments, writes, like Sir Hugh Platt in The Garden of Eden, “to the pleasuring of others,” and title thief though I am, I can not feel that kindly Master Markham grudges me my stolen heading. “ I shall not blush to tell you I had some ambition to publish this book” for the “ pleasing” of “ all Gentlemen and Ladies and others delighting in God’s vegetable creatures.” 
“When the greate books at large are not to be had but at greate price,” or after hours of search in ancient libraries, many modern readers must be denied access to the “Truths and Mysteries” early writers deemed all important, and occasionally, as Platt says, “rolled up in the most cloudy and darksome speech” after having“wrung them from the earth by the painfull hand of experience for your good entertainment.” Surely in a world which pessimists insist is being given over to the devil all should hear of a reliable Anglo-Saxon Salve against “Temptations of the Fiend”? A famous politician begged for the inclusion of a “Leechdom against a man full of elfin tricks,” and suggested that certain citizens of the U.S.A. would welcome “A lithe soft drink against a devil and dementedness,” and might not Scotland Yard consider the possibilities of a prescription said to be infallible “If any evil tempting occur to a man” ? Such simple remedies, brewed, pounded or devised from garden herbes— “honest wortes,” mingled with Holy water, prayers, and flowers whose very names bring healing:— Love o’ the ground, All healand True Love, 
Mothers wort and Queen of the Meadows. As for a salve wherewith to anoint the forehead against visits from “Elf or goblin night visitors,” our nurseries still need it, while an ointment inducing Elves to return and restore our lost childish faith in them would be of even greater value to some of us. 2


Miss Rohde in her exquisite Garden of Herbs quotes a 16th-century receipt 

“ To enable one to see the fairies,” 
a charm I never saw written down, 
though one very similar was told me over thirty years ago by an old woman in the West Country.
 As in Miss Rohde’s version,
 Rosewater and Marigold water, herbs and flowers gathered to the East, played their part, but first in importance
           — or perhaps first in my memory— was, thyme and grass from a fairy ring.
 I often wanted to test its magical properties, but never succeeded in waking at dawn. 

According to my informer, dawn, or just before set of full moon, was the correct hour at which to make one’s first bow to the little unseen folk. 

At that time of my life the inner wonder of her beliefs and friendship with the fairies— which none of her neighbours seemed to doubt— was just as it should be, and nothing much out of the ordinary. 

Now, when I could better appreciate it and have no unsympathetic nursemaid to scoff at pleadings to be allowed a hedgehog in bed to keep me awake on important business, the old lady sleeps forever, and the wood where she said the fairies could be found was cut down in 1916. 
To have missed collecting all the details for preparing such a truly content-giving charm still makes me “monstrous melancholy” ; old adjectives, “prodigious,” “vastly,” and their like, express better than modern words the seriousness of such a loss.
 The loss of enjoyment and belief in ancient charms and customs, not to mention courtesies, has spread like a pest amongst country-folk since Trippers “boomswisshed” into their midst, 

Trippers ready to believe that their name denotes: a rider in bangs, a litter distributor, one willing to murder flowers and behead wild rosebuds with paper streamers: not “one who walks nimbly, or dances with light feet.” Motor horns seem to be “The passing bell, also called the soul bell, ” sounding the knell of better days. 
The above paragraph was gently censored by one with a knowledge of “ Gardens and their Godly treasure to be found therein” that ranks him kin to Thomas Hill, who wrote as finale to The Profitable Art of Gardening, “The favour of God be with thee always.”
 At his suggestion I add a quotation from Grose: 4
“ The passing Bell was antiently rung for two purposes, one to bespeak the Prayers of all good Christians for a Soul just departing; the other to drive away evil Spirits who stood at the Bed’s foot, and about the House, ready to seize their prey, or at least to molest and terrify the Soul in its passage: but by the ringing of that Bell (for Durandus informs us Evil Spirits are much afraid of Bells) they were kept aloof and the Soul like a hunted Hare gained the start or what is by Sportsmen called Law.” Even if many of the old Contentments are gone beyond recall, we can, as he says, loudly “ring the funerall peale” over such fiendish customs as the games of “Mumble Sparrow” and “Cat in Bottle”— inflicting intense suffering on helpless animals.
 The charm and sheer word magic of most of the old writers incline one to forget that the Country Contentments of our ancestors generally were balanced by discontentments.


 The New Art and Mystery of Gossiping and early issues of The Tatler and Spectator hint that 17th- and 18th-century Housewives were faced with difficulties similar to the troubles of a Maisonette wife or Flat-wife of to-day. 5

nine barrows overlooking Wells ,Somerset

Priddy Nine Barrows Cemetery and Ashen Hill Barrow Cemetery are a collection of round barrows, dating from the Bronze Age, near Priddy in the English county of Somerset. They are designated as ancient monuments.[1][2][3]

The barrows sit on crests of land at either end of a field in an area of the Mendip Hills with several Neolithic remains. They are assumed to be related to the Priddy Circles which lie 750 metres (2,460 ft) to the north. Ashen Hill consists of six bowl barrows and two bell barrows aligned east to west while Priddy Nine Barrows divided into one group of seven round barrows and another pair slightly separated from the others.

Excavations in 1815 uncovered cremation burials and grave goods. A geophysical magnetometry survey suggested that there may have been three further barrows.

Blackfriars ship

Blackfriars ship 

This Roman ship was discovered by Peter Marsden in 1962 in the bed of the River Thames, off Blackfriars in the City of London, and excavated in 1962-1963. The ship was a wreck that lay about 120 metres from the Roman shore at the south-west corner of the Roman city of Londinium.

The construction of the ship was dated to about AD 150 by dendrochronology, and its sinking soon after by associated pottery and a coin.

The remains of the forward half of the ship and the extreme aft timbers were excavated, and only the forward half was destroyed during the modern construction work.

 The aft half remains unexcavated.

 The wreck was about 14m long and 6.5m wide, and comprised the bottom and parts of the collapsed sides of a Romano-Celtic ship. The vessel was built of oak (Quercus) and had no keel, but instead two broad keel-planks. A stempost lay at the bow and a sternpost at the stern. The planks were carvel laid and fastened by large iron nails to oak frames - massive floor-timbers in the bottom, and lighter side-frames at the sides. The bottom nails had partly cone-shaped heads hollowed to contain a caulking of thin slivers of hazel (Corylus avellana) in pine resin, and the sides had fully cone-shaped heads similarly caulked. The pointed ends of all nails had been turned over the inboard face of the frames. Between the strakes was a caulking of hazel (Corylus avellana) shavings in a pine resin.

The mast-step was a rectangular socket in a transverse floor-timber about one-third of the length of the vessel from the bow, and in the bottom of the step was a votive offering of a worn bronze coin of Domitian that had been minted in Rome in AD 88-89.

Enough remained to reconstruct the sides up to over 2.5m above the bottom, and this enabled a hydrostatic analysis to be undertaken. This showed that the vessel could probably carry a cargo of about 50 tonnes at a draught of about 1.5m.

The hold lay in the middle of the ship and was lined with a ceiling of oak planks. The wreck was carrying a cargo of building stone by the rivers Medway and Thames from the Maidstone area of Kent, south-east England, to London. Forward of the mast-step in the bottom was an unfinished millstone of Millstone Grit, probably either from the Pennine Hills of northern England or, more likely, from the Namur region by the river Meuse in Belgium.

The ship had certainly sailed at sea for traces of Teredo and Limnoria borings existed in the planks. It appears to have sunk by accident in a collision.

Some timbers are preserved at the Shipwreck Heritage Centre, Hastings, and in the Museum of London, England.

Fusarium graminearum

Gibberella zeae

Fusarium graminearum)

Gibberella zeae
Scientific classification
Kingdom:	Fungi
Division:	Ascomycota
Class:	Sordariomycetes
Order:	Hypocreales
Family:	Nectriaceae
Genus:	Gibberella
Species:	G. zeae
Binomial name
Gibberella zeae (Schwein.) Petch, (1936)
Synonyms
Botryosphaeria saubinetii Dichomera saubinetii Dothidea zeae Fusarium graminearum Fusarium roseum Gibbera saubinetii Gibberella roseum Gibberella saubinetii Sphaeria saubinetii Sphaeria zeae

Gibberella zeae, also known by the name of its anamorph Fusarium graminearum, is a plant pathogen which causes fusarium head blight, a devastating disease on wheat and barley.^[1] The pathogen is responsible for billions of dollars in economic losses worldwide each year.^[2] Infection causes shifts in the amino acid composition of wheat,^[3] resulting in shriveled kernels and contaminating the remaining grain with mycotoxins, mainly deoxynivalenol, which inhibits protein biosynthesis; and zearalenone, an estrogenic mycotoxin. These toxins cause vomiting, liver damage, and reproductive defects in livestock, and are harmful to humans through contaminated food. Despite great efforts to find resistance genes against F. graminearum, no completely resistant variety is currently available. Research on the biology of F. graminearum is directed towards gaining insight into more details about the infection process and reveal weak spots in the life cycle of this pathogen to develop fungicides that can protect wheat from scab infection.

Contents

• 1Life cycle
• 2Host and symptoms
• 3Infection process
• 4Management
• 5Importance
• 6See also
• 7References
• 8External links

Life cycle[edit]

F. graminearum is a haploid homothallic ascomycete. The fruiting bodies, perithecia, develop on the mycelium and give rise to ascospores, which land on susceptible parts of the host plant to germinate. The fungus causes fusarium head blight on wheat, barley, and other grass species, as well as ear rot on corn. The primary inocula are the ascospores, sexual spores which are produced in the perithecia.^[4] Spores are forcibly discharged and can germinate within six hours upon landing on the plant surface. The scab disease is monocyclic; after one cycle of infection with ascospores, the fungus produces macroconidia by asexual reproduction.^[5] These structures overwinter in the soil or in plant debris on the field and give rise to the mycelium in the next season.

Host and symptoms[edit]

The pathogen is capable of causing a variety of diseases: head blight or 'scab' on wheat (Triticum), barley (Hordeum), rice (Oryza), oats (Avena), and Gibberella stalk and ear rot disease on maize (Zea). Additionally, the fungus may infect other plant species without causing any disease symptoms.^[6]
Maize
In Gibberella stalk rot, the leaves on early-infected plants will turn a dull greyish-green, and the lower internodes will soften and turn a tan to dark-brown. A pink-red discoloration occurs within the stalks of diseased tissue. Shredding of the pith may reveal small, round, black perithecia on the stalks.^[7] Gibberella (red) ear rot can have a reddish mold that is often at the ear tip. The infection occurs by colonizing corn silk and symptoms first occur at the ear's apex. The white mycelium turns from pink to red over time, eventually covering the entire ear. Ears that become infected early don't fully develop the reddish mold near the ear tip, as the mold grows between the husks and ear.^[6]
Rice
Gibberella zeae can turn affected seeds red and cause brown discoloration in certain areas on the seed or the entire seed surface. The surface of husks develop white spots that later become yellow and salmon or carmine. Infected grains are light, shrunken and brittle. Stem nodes begin to rot and wilt, eventually causing them to turn black and disintegrate when they are infected by the fungal pathogen.^[7]
Wheat
Brown, dark purple-black necrotic lesions will form on the outer surface of the spikelets, what the wheat ear breaks up into. The lesions may be referred to as scabs, but this is not to be confused and associated with other scab diseases such as those with different host and pathogen. Head blight is visible before the spikes mature.^[7] Spikelets begin to appear water-soaked before the loss of chlorophyll, which gives a white straw color. Peduncles that are directly under the inflorescence can become discolored into a brown-purple color. Tissues of the inflorescence typically become blighted into a bleached tan appearance, and the grain within it atrophies.^[6] The awn will become deformed, twisted and curve in a downward direction.
Barley
Infections on barley are not always visible in the field. Similar to wheat, infected spikelets show a browning or water-soaked appearance. The infected kernels display a tan to dark brown discoloration. During long periods of wetness, pink to salmon-orange spore masses can be seen on the infected spikelets and kernels.^[6] The cortical lesions of infected seeds become a reddish-brown in cool, moist soil. Warm soil can cause head blight to occur after emergence, and crown and basal culm rot can be observed in later plant development.^[7]

Infection process[edit]

Wheat scab caused by G. zeae (artificial inoculation)

F. graminearum infects wheat spikes from anthesis through the soft dough stage of kernel development. The fungus enters the plant mostly through the flowers; however, the infection process is complex and the complete course of colonization of the host has not been described. Germ tubes seem not to be able to penetrate the hard, waxy surface of the lemma and palea which protect the flower. The fungus enters the plant through natural openings such as stomates, and needs soft tissue such as the flowers, anthers and embryo to infect the plant.^[8] From the infected floret, the fungus can grow through the rachis and cause severe damage in a short period of time under favorable conditions. Upon germination of the spores on the anthers and the surface of the developing kernel, hyphae penetrate the epicarp and spread through the seed coat. Successively, the different layers of the seed coat and finally the endosperm are colonized and killed.^[9]

Management[edit]

The control of this disease can be achieved using a combination of the following strategies: fungicide applications, resistance breeding, proper storage, crop rotation, crop residue tillage, and seed treatment. The correct usage of fungicide applications against Fusarium head blight can reduce the disease by 50 to 60 percent.^[10] Fusarium refers to a large genus of soil fungi that are economically important due to the profound effects they have on crops. Application of fungicides is necessary at early heading date for barley and early flowering for wheat, where the early application can limit the infection of the ear. Barley and wheat differ in fungicide application because of their differences in developmental traits.^[11] The disease generally develops late in the season or during storage, so fungicide use is only effective in the early season. Management against insect pests such as ear borers, for corn, will also reduce the infection of the ear from wounds caused by insect feeding.^[12]
Cultivating a variety of hosts that are resistant to Fusarium head blight is one of the most evidence-based and cost-effective ways to manage the disease. Using varieties that have looser tusks that cover the ear are less vulnerable to Fusarium head blight. Once the crop has been harvested, it is essential to store it at low moisture, below 15%, as this will reduce the appearance of Gibberella zeae and Fusarium species in storage.^[12]
Avoiding the planting of small grain crops following other small grain crops or corn and tillage of crop residue minimizes the chances of Fusarium head blight in environmentally favorable years. The rotation of small grains with soybean or other non-host crops has proven to reduce Fusarium head blight and mycotoxin contamination.^[10] Crop rotation with the tillage of residue prevents crops from remaining to infect on the soil surface. Residues can provide an overwintering medium for Fusarium species to cause Fusarium head blight. As a result, the chances of infection are greatly improved in the succeeding small grain crop.^[10] If minimal or no tillage occurs, the residue spreads and allows the fungus to overwinter on stalks and rotted ears of corn and produce spores.
The seeds (kernels) that colonize with the fungus have less resistance because of poor germination. Planting certified or treated seeds can reduce the amount of seedling blight, which is caused by the seeds colonized with the fungus. If it is necessary to replant seeds that were harvested from a Fusarium head blight infected field, then the seeds should be treated to avoid reoccurrence of the infection.^[10]

Importance[edit]

The loss of yield and contamination of seed with mycotoxins, alongside reduced seed quality, are the main contributions to the impact of this disease. Two mycotoxins, trichothecene deoxynivalenol, a strong biosynthesis inhibitor, and zearalenone, an estrogenic mycotoxin, can be found in grains after Fusarium head blight epidemics.^[13] Deoxynivalenol is a type of vomitoxin and, as its name states, is an antifeedant. Livestock that consume crops contaminated with vomitoxin become sick and refuse to eat anymore. Zearalenone is a phytoestrogen, mimicking mammals' estrogen. It can be disastrous if it gets into the food chain, as zearalenone causes abortions in pregnant females and feminization of males.^[14]
In 1982, a major epidemic affected 4 million hectares of the spring wheat and barely growing in the northern Great Plains of North Dakota, South Dakota, and Minnesota. The yield losses exceeded 6.5 million tons worth approximately $826 million, with total losses related to the epidemic near one billion dollars.^[7] Years that followed this epidemic, reported losses that have been estimated between $200-$400 million annually. Losses in barley because of Fusarium head blight are large in part due to the presence of deoxynivalenol. Barley prices from 1996 in Minnesota fell from $3.00 to $2.75 per bushel if the mycotoxin was present and another $0.05 for each part per million of deoxynivalenol present.^[7]

See also[edit]

• Fusarium graminearum genome database
• Ascomycota
• Homothallic
• Ascospore

References[edit]

1. ^ Bai G, Shaner G (2004):Management and resistance in wheat and barley to Fusarium head blight. Annual Review of Phytopathology 42: 135-161 [1]
2. ^ De Wolf ED, Madden LV, Lipps PE (2003): Risk assessment models for wheat Fusarium head blight epidemics based on within-season weather data. Phytopathology 93: 428-435. [2]
3. ^ Beyer M, Aumann J (2008): Effects of Fusarium infection on the amino acid composition of winter wheat grain. Food Chemistry 111: 750-754. [3]
4. ^ Beyer M, Verreet J-A (2005): Germination of Gibberella zeae ascospores as affected by age of spores after discharge and environmental factors. European Journal of Plant Pathology 111: 381-389. [4]
5. ^ Beyer M, Röding S, Ludewig A, Verreet J-A (2004): Germination and survival of Fusarium graminearum macroconidia as affected by environmental factors. Journal of Phytopathology 152: 92-97.[5]
6. ^ Jump up to: ^{a b c d} Rubella, Goswami; Kistler, Corby (2004). "Heading for disaster: Fusarium graminearum on cereal crop" (PDF). Molecular Plant Pathology. 5 (6): 515–525. doi:10.1111/J.1364-3703.2004.00252.X. PMID 20565626.
7. ^ Jump up to: ^{a b c d e f} "headblight of maize (Gibberella zeae)". www.plantwise.org. Retrieved 2017-10-25.
8. ^ Bushnell WR, Leonard KJ (2003): Fusarium head blight of wheat and barley.APS Press, St. Paul, Minnesota
9. ^ Jansen C, Von Wettstein D, Schäfer W, Kogel K-H, Felk A, Maier FJ (2005): Infection patterns in barley and wheat spikes inoculated with wild-type and trichodiene synthase gene disrupted Fusarium graminearum. Proceedings of the National Academy of Sciences 102: 16892-16897 [6]
10. ^ Jump up to: ^{a b c d} "Managing Fusarium Head Blight in Virginia Small Grains". Retrieved 2017-10-25.
11. ^ Alqudah, Ahmad M.; Schnurbusch, Thorsten (2017-05-30). "Heading Date Is Not Flowering Time in Spring Barley". Frontiers in Plant Science. 8: 896. doi:10.3389/fpls.2017.00896. ISSN 1664-462X. PMC 5447769. PMID 28611811.
12. ^ Jump up to: ^{a b} User, Super. "Fusarium and gibberella ear rot (extended information)". maizedoctor.org. Retrieved 2017-10-25.
13. ^ Guenther, John C.; Trail, Frances (2005). "The Development and Differentiation of Gibberella zeae (Anamorph: Fusarium graminearum) during Colonization of Wheat". Mycologia. 97 (1): 229–237. doi:10.1080/15572536.2006.11832856. JSTOR 3762213.
14. ^ Volk, Tom. "Gibberella zeae or Fusarium graminearum, head blight of wheat". botit.botany.wisc.edu. Retrieved 2017-10-25.

External links[edit]

• Interactive Science Experiment Showcasing the Growth of Gibberella zeae (GCSE/A-level)^{[permanent dead link]}
• Fusarium graminearum Database
• Index Fungorum
• USDA ARS Fungal Database

Taxon identifiers	Wikidata: Q288349 EoL: 189378 EPPO: GIBBZE Fungorum: 255496 GBIF: 5251673 iNaturalist: 382448 IRMNG: 10645104 MycoBank: 255496 NBN: NBNSYS0000017983 NCBI: 5518 NZOR: 97dc2e22-d377-4f76-9802-c49ec481b843 uBio: 1221959

Retrieved from "https://en.wikipedia.org/w/index.php?title=Gibberella_zeae&oldid=895500975"

Categories:

• Gibberella
• Fungal plant pathogens and diseases
• Barley diseases
• Wheat diseases
• Fungi described in 1936

Physarum polycephalum

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Physarum polycephalum
Physarum polycephalum plasmodium forming over tree chunk.
Scientific classification
Kingdom:	Protista
Phylum:	Mycetozoa
Class:	Myxogastria
Order:	Physarales
Family:	Physaraceae
Genus:	Physarum
Species:	P. polycephalum
Binomial name
Physarum polycephalum

Physarum polycephalum, literally the "many-headed slime", is a slime mold that inhabits shady, cool, moist areas, such as decaying leaves and logs. Like slime molds in general, it is sensitive to light; in particular, light can repel the slime mold and be a factor in triggering spore growth.

Contents

• 1Characteristics
• 2Life cycle
• 3Streaming behavior
• 4Situational behavior
• 5References
• 6External links

Characteristics[edit]

This protist may be seen without a microscope. P. polycephalum is typically yellow in color, and eats fungal spores, bacteria, and other microbes. P. polycephalum is one of the easiest eukaryotic microbes to grow in culture, and has been used as a model organism for many studies involving amoeboid movement and cell motility.^[1]

Life cycle[edit]

The main vegetative phase of P. polycephalum is the plasmodium (the active, streaming form of slime molds). The plasmodium consists of networks of protoplasmic veins, and many nuclei. It is during this stage that the organism searches for food.^[2] The plasmodium surrounds its food and secretes enzymes to digest it.
If environmental conditions cause the plasmodium to desiccate during feeding or migration, Physarum will form a sclerotium. The sclerotium is basically hardened multinucleated tissue that serves as a dormant stage, protecting Physarum for long periods of time. Once favorable conditions resume, the plasmodium reappears to continue its quest for food.
As the food supply runs out, the plasmodium stops feeding and begins its reproductive phase. Stalks of sporangia form from the plasmodium; it is within these structures that meiosis occurs and spores are formed. Sporangia are usually formed in the open so that the spores they release will be spread by wind currents.
Spores can remain dormant for years if need be. However, when environmental conditions are favorable for growth, the spores germinate and release either flagellated or amoeboid swarm cells (motile stage); the swarm cells then fuse together to form a new plasmodium.

Streaming behavior[edit]

The movement of P. polycephalum is termed shuttle streaming. Shuttle streaming is characterized by the rhythmic back-and-forth flow of the protoplasm; the time interval is approximately two minutes. The forces of the streaming vary for each type of microplasmodium.
The force in amoeboid microplasmodia is generated by contraction and relaxation of a membranous layer probably consisting of actin (type of filament associated with contraction). The filament layer creates a pressure gradient, over which the protoplasm flows within limits of the cell periphery.
The force behind streaming in the dumbbell-shaped microplasmodia is generated by volume changes in both the periphery of the cell and in the invagination system of the cell membrane.

Situational behavior[edit]

P. polycephalum plasmodium cultivating two "islands" of agar substrate overlying a glass coverslip.

Physarum polycephalum has been shown to exhibit characteristics similar to those seen in single-celled creatures and eusocial insects. For example, a team of Japanese and Hungarian researchers have shown P. polycephalum can solve the Shortest path problem. When grown in a maze with oatmeal at two spots, P. polycephalum retracts from everywhere in the maze, except the shortest route connecting the two food sources.^[3] When presented with more than two food sources, P. polycephalum apparently solves a more complicated transportation problem. With more than two sources, the amoeba also produces efficient networks.^[4] In a 2010 paper, oatflakes were dispersed to represent Tokyo and 36 surrounding towns.^[5][6] P. polycephalum created a network similar to the existing train system, and "with comparable efficiency, fault tolerance, and cost". Similar results have been shown based on road networks in the United Kingdom^[7] and the Iberian peninsula (i.e., Spain and Portugal).^[8] Some researchers claim that P. polycephalum is even able to solve the NP-hard Steiner minimum tree problem.^[9]
P. polycephalum can not only solve these computational problems, but also exhibits some form of memory. By repeatedly making the test environment of a specimen of P. polycephalum cold and dry for 60-minute intervals, Hokkaido University biophysicists discovered that the slime mould appears to anticipate the pattern by reacting to the conditions when they did not repeat the conditions for the next interval. Upon repeating the conditions, it would react to expect the 60-minute intervals, as well as testing with 30- and 90-minute intervals.^[10][11]
P. polycephalum has also been shown to dynamically re-allocate to apparently maintain constant levels of different nutrients simultaneously.^[12][13] In particular, specimen placed at the center of a Petri dish spatially re-allocated over combinations of food sources that each had different protein–carbohydrate ratios. After 60 hours, the slime mould area over each food source was measured. For each specimen, the results were consistent with the hypothesis that the amoeba would balance total protein and carbohydrate intake to reach particular levels that were invariant to the actual ratios presented to the slime mould.
As the slime mould does not have any nervous system that could explain these intelligent behaviours, there has been considerable interdisciplinary interest in understanding the rules that govern its behaviour. Scientists are trying to model the slime mold using a number of simple, distributed rules. For example, P. polycephalum has been modeled as a set of differential equations inspired by electrical networks. This model can be shown to be able to compute shortest paths.^[14] A very similar model can be shown to solve the Steiner tree problem.^[9] However, currently these models do not make sense biologically, as they for example assume energy conservation inside the slime mould. Living organisms consume food, so energy can not be conserved. To build more realistic models, more data about the slime mould's network construction needs to be gathered. To this end, researchers are analysing the network structure of lab-grown P. polycephalum.^[15]
In a book^[16] and several preprints that have not been scientifically peer reviewed,^[17][18] it has been claimed that because plasmodia appear to react in a consistent way to stimuli, they are the "ideal substrate for future and emerging bio-computing devices".^[18] An outline has been presented showing how it may be possible to precisely point, steer and cleave plasmodium using light and food sources,^[18] especially Valerian root.^[19] Moreover, it has been reported that plasmodia can be made to form logic gates,^[17] enabling the construction of biological computers. In particular, plasmodia placed at entrances to special geometrically shaped mazes would emerge at exits of the maze that were consistent with truth tables for certain primitive logic connectives. However, as these constructions are based on theoretical models of the slime mould, in practice these results do not scale to allow for actual computation. When the primitive logic gates are connected to form more complex functions, the plasmodium ceased to produce results consistent with the expected truth tables.
Even though complex computations using Physarum as a substrate are currently not possible, researchers have successfully used the organism's reaction to its environment in a USB sensor^[20] and to control a robot.^[21]

References[edit]

Specific

1. ^ "- Journal of Physics D: Applied Physics - IOPscience". iopscience.iop.org. Retrieved 2017-06-08.
2. ^ "Life at the Edge of Sight — Scott Chimileski, Roberto Kolter | Harvard University Press". www.hup.harvard.edu. Retrieved 2018-01-26.
3. ^ Nakagaki, Toshiyuki; Yamada, Hiroyasu; Tóth, Ágota (2000). "Intelligence: Maze-solving by an amoeboid organism". Nature. 407 (6803): 470. doi:10.1038/35035159. PMID 11028990.
4. ^ Nakagaki, Toshiyuki; Kobayashi, Ryo; Nishiura, Yasumasa; Ueda, Tetsuo (November 2004). "Obtaining multiple separate food sources: behavioural intelligence in Physarum plasmodium". Proceedings of the Royal Society B. 271 (1554): 2305–2310. doi:10.1098/rspb.2004.2856. PMC 1691859. PMID 15539357.
5. ^ Tero, Atsushi; Takagi, Seiji; Saigusa, Tetsu; Ito, Kentaro; Bebber, Dan P.; Fricker, Mark D.; Yumiki, Kenji; Kobayashi, Ryo; Nakagaki, Toshiyuki (January 2010). "Rules for Biologically Inspired Adaptive Network Design". Science. 327 (5964): 439–442. Bibcode:2010Sci...327..439T. CiteSeerX 10.1.1.225.9609. doi:10.1126/science.1177894. PMID 20093467.
6. ^ Moseman, Andrew (2010-01-22). "Brainless Slime Mold Builds a Replica Tokyo Subway". Discover Magazine. Retrieved 2011-06-22.
7. ^ Adamatzky, Andrew; Jones, Jeff (2010). "Road planning with slime mould: If Physarum built motorways it would route M6/M74 through Newcastle". International Journal of Bifurcation and Chaos. 20 (10): 3065–3084. arXiv:0912.3967. Bibcode:2010IJBC...20.3065A. doi:10.1142/S0218127410027568.
8. ^ Adamatzky, Andrew; Alonso-Sanz, Ramon (July 2011). "Rebuilding Iberian motorways with slime mould". Biosystems. 5 (1): 89–100. doi:10.1016/j.biosystems.2011.03.007. PMID 21530610.
9. ^ Jump up to: ^{a b} Caleffi, Marcello; Akyildiz, Ian F.; Paura, Luigi (2015). "On the Solution of the Steiner Tree NP-Hard Problem via Physarum BioNetwork". IEEE/ACM Transactions on Networking. PP (99): 1092–1106. doi:10.1109/TNET.2014.2317911.
10. ^ Saigusa, Tetsu; Tero, Atsushi; Nakagaki, Toshiyuki; Kuramoto, Yoshiki (2008). "Amoebae Anticipate Periodic Events". Physical Review Letters. 100 (1): 018101. Bibcode:2008PhRvL.100a8101S. doi:10.1103/PhysRevLett.100.018101. PMID 18232821.
11. ^ Barone, Jennifer (2008-12-09). "Top 100 Stories of 2008 #71: Slime Molds Show Surprising Degree of Intelligence". Discover Magazine. Retrieved 2011-06-22.
12. ^ Dussutour, Audrey; Latty, Tanya; Beekman, Madeleine; Simpson, Stephen J. (2010). "Amoeboid organism solves complex nutritional challenges". PNAS. 107 (10): 4607–4611. Bibcode:2010PNAS..107.4607D. doi:10.1073/pnas.0912198107. PMC 2842061. PMID 20142479.
13. ^ Bonner, John Tyler (2010). "Brainless behavior: A myxomycete chooses a balanced diet". PNAS. 107 (12): 5267–5268. Bibcode:2010PNAS..107.5267B. doi:10.1073/pnas.1000861107. PMC 2851763. PMID 20332217.
14. ^ Becchetti, Luca; Bonifaci, Vincenzo; Dirnberger, Michael; Karrenbauer, Andreas; Mehlhorn, Kurt (2013). Physarum Can Compute Shortest Paths: Convergence Proofs and Complexity Bounds. ICALP. Lecture Notes in Computer Science. 7966. pp. 472–483. doi:10.1007/978-3-642-39212-2_42. ISBN 978-3-642-39211-5.
15. ^ Dirnberger, Michael; Neumann, Adrian; Kehl, Tim (2015). "NEFI: Network Extraction From Images". arXiv:1502.05241 [cs.CV].
16. ^ Adamatzky, Andrew (2010). Physarum Machines: Computers from Slime Mould. World Scientific Series on Nonlinear Science, Series A. 74. World Scientific. ISBN 978-981-4327-58-9. Retrieved 2010-10-31.
17. ^ Jump up to: ^{a b} Andrew, Adamatzky (2010). "Slime mould logical gates: exploring ballistic approach". Applications, Tools and Techniques on the Road to Exascale Computing (IOS Press, ), Pp. 2012: 41–56. arXiv:1005.2301. Bibcode:2010arXiv1005.2301A.
18. ^ Jump up to: ^{a b c} Adamatzky, Andrew (2008-08-06). "Steering plasmodium with light: Dynamical programming of Physarum machine". arXiv:0908.0850 [nlin.PS].
19. ^ Adamatzky, Andrew (31 May 2011). "On attraction of slime mould Physarum polycephalum to plants with sedative properties". Nature Precedings. doi:10.1038/npre.2011.5985.1.
20. ^ Night, Will (2007-05-17). "Bio-sensor puts slime mould at its heart". New Scientist. Retrieved 2011-06-22.
21. ^ Night, Will (2006-02-13). "Robot moved by a slime mould's fears". New Scientist. Retrieved 2011-06-22.

General

• Gawlitta, W; KV Wolf; HU Hoffmann; W Stockem (1980). "Studies on microplasmodia of Physarum polycephalum". Cell and Tissue Research. 209 (1): 71–86. doi:10.1007/bf00219924.
• Henry Stempen; Steven L. Stevenson (1994). Myxomycetes. A Handbook of Slime Molds. Timber Press. ISBN 978-0-88192-439-8.

External links[edit]

Wikimedia Commons has media related to Physarum polycephalum.

• Tedx Talk given by Audrey Dussutour, a French Slime mold Specialist.
• PhysarumPlus: An Internet Resource for Students of Physarum polycephalum and Other Acellular Slime Molds
• Cellular memory hints at the origins of intelligence – The learning and memory potential of Physarum polycephalum
• Time lapse video of Physarum growing in a Petri dish
• Slime Mould Collective - "An international network of/for intelligent organisms"
• NEFI: A software that can be used to extract networks from images of Physarum.