The molecular genetic research leads researchers to believe that glutinous rice - which differs from non-glutinous, or common, rice on account of a mutation in its Waxy gene that suppresses the formation of a starch called amylose - most likely originated a single time in Southeast Asia. Further, DNA evidence - namely the lower-than-expected genetic variability in the Waxy gene - suggests that early domesticators of glutinous rice liked its adhesive quality and wanted to preserve that particular trait.
Dr. Michael Purugganan, associate professor of genetics, and Dr. Kenneth Olsen, post-doctoral research associate in genetics, publish their findings in the Oct. 23 edition of Genetics.
To learn more about the origin and evolution of sticky rice, the researchers studied 105 glutinous and non-glutinous samples of rice donated from the multitudinous stock kept by the International Rice Research Institute in Los Banos, Philippines.
Rice contains two starches: amylose and amylopectin. Glutinous rice lacks amylose; in fact, it is the lack of amylose that gives it its sticky composition. Non-glutinous rice - what you'd find if you cooked up a name-brand package of rice from the grocery store, for example - contains up to 30 percent amylose; the result is rice with grains that separate.
Glutinous rice is the staple food in some areas in Southeast Asia, including parts of Laos, Thailand and Cambodia, the researchers say. Sticky rice has also migrated north to become an important part of the diet in places like China and Japan. Used primarily in a number of desserts - rice cakes, for example - sticky rice has achieved important cultural standing in East and Southeast Asia.
But Asian folklore diverges on the origin of glutinous
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Contact: Dr. Michael Purugganan
michael_purugganan@ncsu.edu
919-515-1761
North Carolina State University
22-Oct-2002