Posted by punnya on June 8, 2013, 10:30 p.m.
pple
| Apple | |
|---|---|
 | |
| A typical apple | |
| Scientific classification | |
| Kingdom: | Plantae |
| (unranked): | Angiosperms |
| (unranked): | Eudicots |
| (unranked): | Rosids |
| Order: | Rosales |
| Family: | Rosaceae |
| Genus: | Malus |
| Species: | M. domestica |
| Binomial name | |
| Malus domestica Borkh., 1803 | |
| Synonyms | |
The apple is the pomaceous fruit of the apple tree, species Malus domestica in the rose family (Rosaceae). It is one of the most widely cultivated tree fruits, and the most widely known of the many members of genus Malus that are used by humans. Apples grow on small, deciduous trees. The tree originated in Central Asia, where its wild ancestor, Malus sieversii, is still found today. Apples have been grown for thousands of years in Asia and Europe, and were brought to North America by European colonists. Apples have been present in the mythology and religions of many cultures, including Norse, Greek and Christian traditions. In 2010, the fruit's genome was decoded, leading to new understandings of disease control and selective breeding in apple production.
There are more than 7,500 known cultivars of apples, resulting in a range of desired characteristics. Different cultivars are bred for various tastes and uses, including cooking, fresh eating and cider production. Domestic apples are generally propagated bygrafting, although wild apples grow readily from seed. Trees are prone to a number of fungal, bacterial and pest problems, which can be controlled by a number of organic and non-organic means.
About 69 million tonnes of apples were grown worldwide in 2010, and China produced almost half of this total. The United States is the second-leading producer, with more than 6% of world production. Turkey is third, followed by Italy, India and Poland. Apples are often eaten raw, but can also be found in many prepared foods (especially desserts) and drinks. Many beneficial health effects have been found from eating apples; however, two forms of allergies are seen to various proteins found in the fruit.
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Botanical information
The apple forms a tree that is small and deciduous, reaching 3 to 12 metres (9.8 to 39 ft) tall, with a broad, often densely twiggy crown.[3] The leaves are alternately arranged simple ovals 5 to 12 cm long and 3–6 centimetres (1.2–2.4 in) broad on a 2 to 5 centimetres (0.79 to 2.0 in) petiole with an acute tip, serrated margin and a slightly downy underside. Blossoms are produced in spring simultaneously with the budding of the leaves. The flowers are white with a pink tinge that gradually fades, five petaled, and 2.5 to 3.5 centimetres (0.98 to 1.4 in) in diameter. The fruit matures in autumn, and is typically 5 to 9 centimetres (2.0 to 3.5 in) in diameter. The skins of ripe apples range from red to yellow to green in colouration, and covered in a protective layer of epicuticular wax[4], while the flesh is pale yellowish-white. The center of the fruit contains five carpels arranged in a five-point star, each carpel containing one to three seeds, called pips.[3]
Wild ancestors
The original wild ancestor of Malus domestica was Malus sieversii, found growing wild in the mountains of Central Asia in southern Kazakhstan, Kyrgyzstan, Tajikistan, and Xinjiang, China.[3][5] Cultivation of the species, most likely beginning on the forested flanks of the Tian Shan mountains, progressed over a long period of time and permitted secondary introgression of genes from other species into the open-pollinated seeds. Significant exchange with Malus sylvestris, the crabapple, resulted in current populations of apples to be more related to crabapples than to the more morphologically similar progenitor Malus sieversii. In strains without recent admixture the contribution of the latter predominates.[6][7][8]
Genome
In 2010, an Italian-led consortium announced they had decoded the complete genome of the apple in collaboration with horticultural genomicists at Washington State University,[9] using the Golden delicious variety.[10] It had about 57,000 genes, the highest number of any plant genome studied to date[11] and more genes than the human genome (about 30,000).[12] This new understanding of the apple genome will help scientists in identifying genes and gene variants that contribute to resistance to disease and drought, and other desirable characteristics. Understanding the genes behind these characteristics will allow scientists to perform more knowledgeable selective breeding. Decoding the genome also provided proof that Malus sieversii was the wild ancestor of the domestic apple—an issue that had been long-debated in the scientific community.[13]
History
The center of diversity of the genus Malus is in eastern Turkey. The apple tree was perhaps the earliest tree to be cultivated,[14]and its fruits have been improved through selection over thousands of years. Alexander the Great is credited with finding dwarfed apples in Kazakhstan in Asia in 328 BCE;[3] those he brought back to Macedonia might have been the progenitors of dwarfing root stocks. Winter apples, picked in late autumn and stored just above freezing, have been an important food in Asia and Europe for millennia, as well as in Argentina and in the United States since the arrival of Europeans.[14] Apples were brought to North America by colonists in the 17th century,[3] and the first apple orchard on the North American continent was planted in Boston by ReverendWilliam Blaxton in 1625.[15] The only apples native to North America are crab apples, which were once called "common apples".[16]Apple varieties brought as seed from Europe were spread along Native American trade routes, as well as being cultivated on Colonial farms. An 1845 United States apples nursery catalogue sold 350 of the "best" varieties, showing the proliferation of new North American varieties by the early 19th century.[16] In the 20th century, irrigation projects in Washington state began and allowed the development of the multibillion dollar fruit industry, of which the apple is the leading product.[3]
Until the 20th century, farmers stored apples in frostproof cellars during the winter for their own use or for sale. Improved transportation of fresh apples by train and road replaced the necessity for storage.[17][18] In the 21st century, long-term storage again came into popularity, as "controlled atmosphere" facilities were used to keep apples fresh year-round. Controlled atmosphere facilities use high humidity and low oxygen and carbon dioxide levels to maintain fruit freshness.[19]
