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An apple is a round, edible fruit produced by an apple tree (Malus domestica). Apple trees are cultivated worldwide and are the most widely grown species in the genus Malus. The tree originated in Central Asia, where its wild ancestor, Malus sieversii, is still found. Apples have been grown for thousands of years in Asia and Europe and were introduced to North America by European colonists. Apples have religious and mythological significance in many cultures, including Norse, Greek, and European Christian tradition.
Apples grown from seed tend to be very different from those of their parents, and the resultant fruit frequently lacks desired characteristics. For commercial purposes, including botanical evaluation, apple cultivars are propagated by clonal grafting onto rootstocks.
Apple trees grown without rootstocks tend to be larger and much slower to fruit after planting. Rootstocks are used to control the speed of growth and the size of the resulting tree, allowing for easier harvesting.
There are more than 7,500 cultivars of apples. Different cultivars are bred for various tastes and uses, including cooking, eating raw, and cider or apple juice production. Trees and fruit are prone to fungal, bacterial, and pest problems, which can be controlled by a number of organic and non-organic means.
In 2010, the fruit's genome was sequenced as part of research on disease control and selective breeding in apple production.
The word apple, whose Old English ancestor is æppel, is descended from the Proto-Germanic noun *aplaz, descended in turn from Proto-Indo-European *h₂ébōl.
As late as the 17th century, the word also functioned as a generic term for all fruit including nuts -such as the 14th-century Middle English expression appel of paradis, meaning a banana.
More information: National Geographic
Apples are diploid (though triploid cultivars are not uncommon), have 17 chromosomes and an estimated genome size of approximately 650 Mb. Several whole genome sequences have been completed and made available. The first one in 2010 was based on the diploid cultivar 'Golden Delicious'. However, this first whole genome sequence turned out to contain several errors in part owing to the high degree of heterozygosity in diploid apples which, in combination with an ancient genome duplication, complicated the assembly. Recently, double- and trihaploid individuals have been sequenced, yielding whole genome sequences of higher quality.
The first whole genome assembly was estimated to contain around 57,000 genes, though the more recent genome sequences support estimates between 42,000 and 44,700 protein-coding genes. The availability of whole genome sequences has provided evidence that the wild ancestor of the cultivated apple most likely is Malus sieversii. Re-sequencing of multiple accessions has supported this, while also suggesting extensive introgression from Malus sylvestris following domestication.
Malus sieversii is recognized as a major progenitor species to the cultivated apple, and is morphologically similar. Due to the genetic variability in Central Asia, this region is generally considered the center of origin for apples.
The apple is thought to have been domesticated 4000-10000 years ago in the Tian Shan mountains, and then to have travelled along the Silk Road to Europe, with hybridization and introgression of wild crabapples from Siberia (M. baccata), the Caucasus (M. orientalis), and Europe (M. sylvestris). Only the M. sieversii trees growing on the western side of the Tian Shan mountains contributed genetically to the domesticated apple, not the isolated population on the eastern side.
More information: Historic Sites North Carolina
but Newton was the one who asked why.
Bernard Baruch
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