Plant Science

Cereal Mutation

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Science  21 Aug 2009:
Vol. 325, Issue 5943, pp. 921
DOI: 10.1126/science.325_921a
CREDIT: PALMER ET AL., PLOS ONE 4, E6301 (2009)

More than 9000 years ago, the domestication of barley began. Today, wild barley carries spikelets with two rows of grains, whereas domesticated barley varieties are found with two or six rows. The latter has a higher protein content and greater fecundity, although the grains of the former are larger and hence yield roughly equal biomass. Six-row varieties are commonly preferred and have been available in northern Africa for thousands of years. A loss-of-function mutation in the gene Vrs1 produces a six-row morphology.

Archaeological analysis at Qasr Ibrim, a settlement on the boundary of the Nubian and Roman Empires, has shown that two-row barley (shown above) predominates. By analysis of ancient barley samples found at Qasr Ibrim, Palmer et al. discovered the same loss-of-function mutation in Vrs1 and infer that a subsequent and as yet unidentified mutation derived the two-row morphology from the domesticated six-row variety. The agricultural preference for two-row barley hints at a competitive advantage, such as its greater tolerance to drought. That the several cultures that occupied Qasr Ibrim during the past 3000 years all adopted the local two-row barley suggests that this strain is particularly well suited for cultivation at this locale.

PLoS ONE 4, e6301 (2009).

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