The genome sequence of segmental allotetraploid peanut Arachis hypogaea

TLDR

The cultivated peanut is a hybrid allotetraploid derived from two ancestral species, carrying nearly complete chromosome sets from each. New polyploid hybrids from ancestral species demonstrate that homeologous recombination can produce phenotypic variation, exemplified by spontaneous flower color changes. The peanut genome sequence reveals extensive mobile‑element activity, deletions, and homeologous recombination that generated diversity, supporting a single origin and facilitating domestication over diploid relatives.

Abstract

Like many other crops, the cultivated peanut (Arachis hypogaea L.) is of hybrid origin and has a polyploid genome that contains essentially complete sets of chromosomes from two ancestral species. Here we report the genome sequence of peanut and show that after its polyploid origin, the genome has evolved through mobile-element activity, deletions and by the flow of genetic information between corresponding ancestral chromosomes (that is, homeologous recombination). Uniformity of patterns of homeologous recombination at the ends of chromosomes favors a single origin for cultivated peanut and its wild counterpart A. monticola. However, through much of the genome, homeologous recombination has created diversity. Using new polyploid hybrids made from the ancestral species, we show how this can generate phenotypic changes such as spontaneous changes in the color of the flowers. We suggest that diversity generated by these genetic mechanisms helped to favor the domestication of the polyploid A. hypogaea over other diploid Arachis species cultivated by humans. The genome sequence of segmental allotetraploid peanut suggests that diversity generated by genetic deletions and homeologous recombination helped to favor the domestication of Arachis hypogaea over its diploid relatives.