"Waxy corn" is a general term for "glutinous corn".
A type of corn characterized by its sticky texture when cooked as a result of larger amounts of amylopectin is called sticky corn.The corn was first described in 1909.The American breeders used this plant as a genetic marker to find hidden genes in other maize breeding programs.In 1922, a researcher found that the endosperm of waxy maize contained only mylopectin and no amylose starch molecule in opposition to normal dent maize varieties that contain both.Until World War II, the main source of tapioca in the USA was waxy maize, but when Japan severed the supply lines of the States, they forced processors to turn to other sources.Amylopectin can be found in food products, but also in the textile, corrugating and paper industry.
When feeding trials showed that waxy maize could produce more efficient feed gains, interest in the maize suddenly increased.The synthesis of amylose in the endosperm can be stopped by a defect in metabolism.The code is based on a single gene.Waxy maize has to be isolated from any nearby normal maize fields by at least 200 meters.
The history of waxy maize is not known.The first mention of it was found in the archives of the USDA.The Rev. was in 1908.A sample of seeds was sent to the U.S. office of foreign seed and plant introduction.There is a note with the seeds.The colors are said to be the same variety.The seeds were planted by a man named Guy N. Collins near Washington, D.C., and may be found to be of some use.He was able to grow 53 plants to maturity and make a detailed characterisation of them, which was published in a USDA bulletin in December 1909.[2]
The plant was rediscovered in the Philippines in 1920.When screening the distribution of maize in Asia, Kuleshov found it in many other places.There is a citation needed.
The question of whether maize was known in the Orient before it was discovered in America is related to the discovery of a distinct type of maize in China.The question was closed by De Candolle at the end of the 19th century.Despite the contrary opinion of some authors, I think these two assertions are positive.
A re-examination of the question was suggested by the finding of this unique variety of maize.He states that the Portuguese arrived in China in 1516 with maize.According to Collins, the maize has arisen by a way of change.It was difficult for some scholars to believe that from 1516 on the American plant had had time to penetrate into a wild country that was not accessible to foreigners.[3]
We are able to match both of these arguments.At first, we know that it's common.If maize was introduced into Asia in the Post-Columbian times, it would have met an acute and pressing need like the potato in Ireland.[5]
There are 6000 local histories in China written from A.D. 347 on.The first accurate description of maize was published in the 16th century.The introduction of maize into China may have happened two or three decades before 1550...We are not aware of a single plant fragment, artifact, illustration, or written record to prove that maize reached Asia before 1492.Any statement about its occurrence there in the past is to be regarded with skepticism.The two assertions of De Candolle are still valid.There is a citation needed.
The new plants were described by Collins as having a number of unique characteristics.The unique features allow the plant to resist the drying out of the silks at the time of flowering.Although the plants produced small ears that they could not compete with the improved varieties, the possession of this adaptation gave the new type an economic interest.The effort has been made to combine the desirable characteristics of this small variety with those of larger and more productive types.[9]
Collins suspected that there was a difference in chemical composition when he looked at the appearance of normal and waxy maize endosperm.The percentages were within the normal range.In view of the recent development of specialized maize products as human food, the unique type of starch may be of some economic importance.For a long time the main use of waxy maize was a genetic marker for other maize breeding programs.Some of the traits were used to "tag" the existence of hidden genes and follow them through breeding programs.It is possible that waxy maize would have become extinct in the USA without this special application in breeding.There is a citation needed.
In 1922, P. Weatherwax of Indiana University in Bloomington reported that there was a rare form of amylopectin in waxy maize.He found that the rare starch stained red with iodine, unlike the normal starch which stained blue.French et al.They were joined by Sprague, Brimhall, et al.The endosperm of waxy maize is mostly amylopectin.Parnell had shown the presence of amylopectin in rice.It was [13].
The waxy trait was introduced into a regular high-yielding hybrid maize by G.F. Sprague and other plant breeders at Iowa State College in 1937.By this time, the waxy plant no longer had the peculiar structural traits noted by Collins, probably due to years of crossing into various genetic stocks.Only the unique endosperm was retained.The main source of pure amylopectin at this time was the cassava plant, a tropical shrub with a large underground tuber.There are no comments at this time.
When the supply lines of the States were severed during World War II, processors were forced to use waxy maize.Waxy maize appeared to be especially suitable for this purpose because it could be processed with the same equipment already used for ordinary maize.In 1942 and 1943, the production of waxy maize in Iowa for industrial use amounted to over 300 metric tons.There were only 5 varieties of waxy maize available in 1944.81650 tons of grains were produced in 1943 to cover the special requirements for amylopectin.All the waxy maize produced in the U.S. was grown for food or industrial processing after World War II.Most of the maize was grown in Iowa, Illinois, and Indiana.[18]
The Southern corn leaf disease epidemic occurred in 1970.They swept the U.S. corn belt.At the same time, at least 80% of the maize being grown in the U.S. was susceptible to the disease because it contained the "Texas type" male-sterile cytoplasm, which allowed production of hybrid seed without mechanical or hand detasseling.There was a scramble in 1971 to find any kind of maize that had normal cytoplasm.The seed of waxy maize made it to the market.Individual genes such as wx, o2 and Htl were transferred to regular dent corn through backcrossing.[19]
Some farmers fed this grain to their cattle and they liked it.Feeding trials showed that the waxy maize produced more efficient weight gains.The maize type became the subject of major research importance after interest in it suddenly mushroomed.[18]
In 2002, an estimated 1,200,000 to 1,300,000 tonnes of waxy maize was produced in the United States, representing only 0,5% of the total maize production.[20]
The normal dent maize has a content of 25% amylose with the rest being a mylopectin and the intermediate fraction.There are different percentages among cultivars and with kernels development.For 399 maize varieties, amylose percentage ranged from 20 to 36%.There are maize germplasm that range from less than 20 to 100% complement of amylopectin.There is 100% amylopectin in waxy maize.[13]
Fractionation of normal starch to obtain pure amylose is very expensive.There is a citation needed.
Waxy endosperm is a defect in metabolism that is acted against by natural selection in most maize populations.[5]
In an open-pollinated maize variety, ten to twenty plants are required for adequate representation of genetic diversity.Since the number of ears saved for seed by ancient Asian maize cultivators with only small plots of land at their disposal was often smaller than this, and since new maize populations are sometimes established by growing the progeny of a single ear, there must have been genetic drift.There is a citation needed.
In parts of Asia of varieties with waxy endosperm, there is a striking example of genetic drift.In maize races of America such a variety is unknown, but it has been found in New England flint maize and in a South American variety.There are 26 and 27 items.
Artificial selection is to blame for the fact that waxy maize occurs so frequently in a part of the world that also has waxy rice, sorghum, and millet.After the discovery of America, the people of Asia were familiar with the waxy varieties of cereals and used them for special purposes.The fact that waxy endosperm came to their attention is probably due to genetic drift.The gene for waxy endosperm, which is low in American maize, is high in some Asian maize.There is a citation needed.
The practice of growing maize as single plants among other cereals would result in some degree of self-pollination and, in any stock in which the waxy gene was present, would inevitably lead in a very short time to the establishment of pure waxy.[5]
Genetics began with describing the physical appearance of the maize.These genes were coupled to other genes.The best collection of genes found in higher plants are known as the waxy locus.[29]
Some of the waxy mutants are very stable.The stable mutants remains the same and the unstable one changes because of the addition of transposable elements.The excellent book of Neuffer, Coe et al. can be found here.It is recommended.There is a citation needed.
During the 20th century, it has been the subject of major research because it is expressed in an easy identifiable non lethal phenotype.Nelson made a genetic map of most of them.
For all known amylose and amylopectine forming genes, the waxy gene is Epistatic.It causes dramatic increases in sugars and WSP in a su1 background with ae or aedu genes.There is a citation needed.
The male and female gametophytes express the wx locus in the endosperm.Depending on the source, Amylose and amylopectin have different IA values of 19 to 20 and 1%, respectively.Weatherwax discovered this process in 1922.10
The amount of apparent amylose can be determined either by measuring the absorbency of the starch-iodine complex and relating this value to that of pure a mylose and a Mylopectin standards.[45]
The values used on the iodine binding are only estimates of amylose content because of the differences in binding abilities.There is a small measure of apparent amylose when a mylopectin molecule has long external branches.There is a citation needed.
There is no amylose peak in the wx- containing starches.The maximum absorbency of a starch-iodine complex is referred to as the lambda max.[39]
Plants with genes on the Wx:wx can be characterized by staining the pollen.The blue and brown pollens are very helpful in backcrossing program.The whole of the plant will be brown if it is homozygous.Being dominant will make the iodine appear blue.There is a citation needed.
Normal dent maize has two different pathways for the formation of starch, one leading to branched chain and the other to straight-chain polysaccharides.48
The NDP-glucose-starch glucosyltransferase is found in the Wx code.The amylose biosynthesis is done by this specific starch synthase.The Wx Gen catalyses the linkage from glucose to amylose in the developing endosperm.The major component of maize is the amyloplasts.Nelson showed that the endosperm had very low glucosyltransferase activity.There is a citation needed.
Akatsuka noticed a linear correlation between the activity of the transferase and the Wx dosage in maize.The amylose content was the same in both types, suggesting that activity of the transferase is not directly linked to it.There is a citation needed.
There is evidence of a molecule that is intermediate in size to amylose and a mylopectin in maize.The number of chains per molecule and average length of the chains in the intermediate fraction are different from those in either amylopectin or a mylose.The researchers used indirect evidence from IA to show the presence of normal maize starch of 5 to 7% intermediate polysaccharides.There is a citation needed.
It was said that amylopectin contained three different types of chains.Each macromolecule has one C-chain, which is the only reducing group.The B-chains are linked to the macromolecules linked by their potential reducing group.The degree of multiple branching is measured by the ratio of A-B chains.The exact arrangement of chains within the amylopectin molecule is not clear.[39]
There is an effect on the amylose and amylopectine structure of the maize when it is combined with another maize variant.
Extra measures are needed to make waxy maize starch on an industrial scale.There is a citation needed.
New varieties with the waxy locus are relatively easy to breed through back-crossing, but their productivity is less than that of dent maize.There is a citation needed.
To prevent cross-pollination, waxy maize has to be isolated from any nearby fields by at least 200 meters.There are volunteer dent maize plants that sprouted from the previous year's debris.A few volunteers in a field of maize will cause dents in the whole field, instead of the waxy grains with amylopectin.There is a citation needed.
Most of the waxy grain is produced under contract.The extra costs incurred from the lower yield and the extra handling are paid for by a premium.There is a citation needed.
Amylopectin can be used to make a clear paste with a sticky or tacky surface.The paste rheology is similar to pastes of root or tuber starches.Amylopectine is more stable and has a lower tendency to retrogradate.The different properties of normal dent corn starch, containing also amylose, are used mainly in following different applications.There is a citation needed.