Tobacco stands out as a complex allotetraploid with a large 4.5 Gb genome with significant proportion (>70%) of repeats. As a species, N. tabacum (2n=4x=48) evolved through the interspecific hybridization of the ancestors of Nicotiana sylvestris (2n=24, maternal donor) and Nicotiana tomentosiformis (2n=24, paternal donor) about 200,000 years ago. Common tobacco (Nicotiana tabacum) is one of the most widely cultivated non-food crops worldwide and is grown in ~120 countries. It belongs to the Nicotiana genus, which is named after Jean Nicot de Villemain who, in 1560, became the first person to import these plants from the Americas to Europe. The term Nicotiana was originally used by Adam Lonitzer to describe tobacco plants in 1630 and in 1788 by Carl von Linné (Linnaeus) to designate the entire genus. Over 75 naturally occurring Nicotiana species, including 49 native to America and 25 native to Australia, have been classified by Goodspeed and Knapp. Most commercial tobaccos cultivated today belong to the species Nicotiana tabacum L., for which >1,600 N. tabacum cultivated varieties (cultivars) are listed in the National Plant Germplasm System. The three most commonly used tobacco types are Flue-Cured (or Virginia), Burley and Oriental, which are traditionally grown and harvested under different agricultural practices.

The text above was extracted from Sierro, N. et al. 2014

Nicotiana tabacum plants in the field.

Two versions of the Nicotiana tabacum genome (Sierro, N. et al. 2014 and Edwards, K. et al. 2017) and the genomes from N. sylvestris and N. tomentosiformis have been sequenced:

• Edwards, K. et al. A reference genome for Nicotiana tabacum enables map-based cloning of homeologous loci implicated in nitrogen utilization efficiency.
  BMC Genomics (2017)
• Sierro, N. et al. The tobacco genome sequence and its comparison with those of tomato and potato.
  Nature Communications 5 (2014).
• Sierro, N. et al. Reference genomes and transcriptomes of Nicotiana sylvestris and Nicotiana tomentosiformis.
  Genome Biology 14, R60 (2013).