The cultivated peanut is an allotetraploid (AABB, 2n=4x=40) that carries the A genome from A. duranensis and the B genome from A. ipaensis. These two ancestral diploids separated from each other about 3 million years ago. The genome merger, allopolyploidy event, ocurred relatively very recently, five to ten thousand years ago, followed by domestication in South America from where it appeared in most part of the world by 1600.

栽培的花生基因组是4倍体，还没测，这次是测的4倍体祖先的A基因组和B基因组，这两个基因组是二倍体，分别是A genome from A. duranensis and the B genome from A. ipaensis。

N50,scaffold,length, 947955 5343284

N50,contig,length, 22293 23492

  组装结果不是很好，contigN50 才20多K

ng.3517.pdf

 The genome sequences of Arachis duranensis and Arachis ipaensis, the diploid ancestors of cultivated peanut

David John Bertioli1,2,27, Steven B Cannon3,27, Lutz Froenicke4,5,27, Guodong Huang6,27, Andrew D Farmer7, Ethalinda K S Cannon8, Xin Liu6, Dongying Gao2, Josh Clevenger9, Sudhansu Dash7, Longhui Ren10, Márcio C Moretzsohn11, Kenta Shirasawa12, Wei Huang13, Bruna Vidigal1,11, Brian Abernathy2, Ye Chu14, Chad E Niederhuth15, Pooja Umale7, Ana Cláudia G Araújo11, Alexander Kozik4, Kyung Do Kim2, Mark D Burow16,17, Rajeev K Varshney18, Xingjun Wang19, Xinyou Zhang20, Noelle Barkley21,22, Patrícia M Guimarães11, Sachiko Isobe12, Baozhu Guo23, Boshou Liao24, H Thomas Stalker25, Robert J Schmitz15, Brian E Scheffler26, Soraya C M Leal-Bertioli2,11, Xu Xun6, Scott A Jackson2, Richard Michelmore4,5 & Peggy Ozias-Akins9,14

Cultivated peanut (Arachis hypogaea) is an allotetraploid with closely related subgenomes of a total size of ~2.7 Gb. This makes the assembly of chromosomal pseudomolecules very challenging. As a foundation to understanding the genome of cultivated peanut, we report the genome sequences of its diploid ancestors (Arachis duranensis and Arachis ipaensis). We show that these genomes are similar to cultivated peanut’s A and B subgenomes and use them to identify candidate disease resistance genes, to guide tetraploid transcript assemblies and to detect genetic exchange between cultivated peanut’s subgenomes. On the basis of remarkably high DNA identity of the A. ipaensis genome and the B subgenome of cultivated peanut and biogeographic evidence, we conclude that A. ipaensis may be a direct descendant of the same population that contributed the B subgenome to cultivated peanut.

Cultivated peanut, Arachis hypogaea, is an important oilseed crop with a total global production area of some 59 million acres. Besides oil, peanut seed is rich in protein and a good source of vitamins and minerals. In U.S.A. the consumption is more than six pounds of peanuts per capita annually. U.S. peanut production, valued at $2 billion annually, extends from Virginia south to Florida and westward to New Mexico.

In the U.S., peanuts are an important crop in several southeastern states, partly due to the work of the African-American botanist George Washington Carver, who in the 1920s and 1930s promoted them as an alternative crop to cotton; he famously described 145 different products made from peanuts, many of which he himself developed.

The peanut or groundnut (also known as earthnuts, goober peas, monkey nuts, pygmy nuts and pig nuts), is an annual herbaceous plant in the Fabaceae (legume or bean family) now grown in tropical and warm-temperate regions worldwide for its seeds and their oil. The seeds contain up to 50% oil making it one of the important oilseed crops in the world. After pollination, the flower stalks elongate, growing to 6 cm long, and push the developing pods into the ground, so that the fruit must be dug up from the soil to be harvested. The latin term hypogaea refers to this "below+ground" growth of the pod. Although appearing as and referred to as a nut, it is actually the underground pod of a legume, rather than a true nut. The fruit is an indehiscent legume (a pod that does not have sutures or split open freely), typically containing 1 to 3 soft seeds (sometimes as many as 6).

Origin:
Cultivated peanut originated and was domesticated in South and Central America 3-5 thousand years ago, derived all of its genetic material from two wild ancestors, A. duranensis and A. ipaensis whose genomes merged several thousand years ago, in a rare genetic event. The wild species, therefore, have half as much genetic material as cultivated peanut. These two “simpler” genomes have first been sequenced toward achieving its ultimate goal: the complete genomic sequence for cultivated peanut.