Aromatic rice explained

Aromatic rice is one of the major types of rice.^[1] It is a medium- to long-grained rice. It is known for its nutty aroma and taste, which is caused by the chemical compound 2-acetyl-1-pyrroline.^[2] Varieties of aromatic rice include Ambemohar, Basmati, Jasmine, Sona Masuri, Texmati, Tulaipanji, Tulshimala, Wehani, Kalijira, Chinigura, Gobindobhog, Kali Mooch and wild Pecan rice.^[3] When cooked, the grains have a light and fluffy texture except for Gobindobhog rice which is sticky in texture.

Aromatic rice produces more 2-acetyl-1-pyrroline than usual due to a loss-of-function mutation in the BADH2 gene. The BADH2 mutation can be transferred by conventional breeding; it is a recessive trait.^[4] Gene editing can be used to induce a similar mutation in ordinary rice, turning them aromatic without affecting other traits.^[5]

The aromatic cultivar group originated in the Indian subcontinent about 2400 - 4000 years ago, from an admixture of the newly-introduced japonica rice (carrying the BADH2 mutation) and the local aus rice. Not all members of the cultivar group are fragrant.^[6] The aromatic group is considered part of the japonica subspecies.^[7]

Further reading

• R.K. Singh, U.S. Singh and G.S. Khush (editors). (2000). Aromatic rices. New Delhi : Oxford & IBH Pub. Google Books.

Notes and References

1. Web site: The U.S. Rice Export Market. USDA. Nov 2000.
   "There are four types of rice traded globally: indica, japonica, aromatic, and glutinous."
2. Enhanced resistance to two stem borers in an aromatic rice containing a synthetic cryIA(b) gene . 10.1023/A:1009695324100 . 3. 5 . Molecular Breeding. 401–414. 1997 . Ghareyazie . Behzad . Alinia . Faramarz . Menguito . Corazon A. . Rubia . Leila G. . De Palma . Justina M. . Liwanag . Evelyn A. . Cohen . Michael B. . Khush . Gurdev S. . Bennett . John . 34294922 .
3. Book: Aromatic Rices. 2000. Int. Rice Res. Inst.. 978-81-204-1420-4. 8–.
4. Chen . S . Yang . Y . Shi . W . Ji . Q . He . F . Zhang . Z . Cheng . Z . Liu . X . Xu . M . Badh2, encoding betaine aldehyde dehydrogenase, inhibits the biosynthesis of 2-acetyl-1-pyrroline, a major component in rice fragrance. . The Plant Cell . July 2008 . 20 . 7 . 1850–61 . 10.1105/tpc.108.058917 . 18599581. 2518245 .
5. Shan . Q . Zhang . Y . Chen . K . Zhang . K . Gao . C . Creation of fragrant rice by targeted knockout of the OsBADH2 gene using TALEN technology. . Plant Biotechnology Journal . August 2015 . 13 . 6 . 791–800 . 10.1111/pbi.12312 . 25599829 . free.
6. Civáň . Peter . Ali . Sajid . Batista-Navarro . Riza . Drosou . Konstantina . Ihejieto . Chioma . Chakraborty . Debarati . Ray . Avik . Gladieux . Pierre . Brown . Terence A . Origin of the Aromatic Group of Cultivated Rice (Oryza sativa L.) Traced to the Indian Subcontinent . Genome Biology and Evolution . 2019-03-01 . 11 . 3 . 832–843 . 10.1093/gbe/evz039. 30793171 . 6427689 .
7. Garris . Amanda J. . Tai . T. H. . Coburn . J. . Kresovich . S. . McCouch . S. . Susan McCouch . 2004 . Genetic structure and diversity in Oryza sativa L. . . 15654106 . 10.1534/genetics.104.035642 . 169 . 3 . 1631–1638 . 1449546.