Current Biology
Volume 22, Issue 2, 24 January 2012, Pages 160-165
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Maternal Control of Nutrient Allocation in Plant Seeds by Genomic Imprinting

https://doi.org/10.1016/j.cub.2011.11.059Get rights and content
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Summary

Imprinted genes are commonly expressed in mammalian placentas and in plant seed endosperms, where they exhibit preferential uniparental allelic expression. In mammals, imprinted genes directly regulate placental function and nutrient distribution from mother to fetus [1, 2, 3, 4]; however, none of the >60 imprinted genes thus far reported in plants have been demonstrated to play an equivalent role in regulating the flow of resources to the embryo [5, 6, 7]. Here we show that imprinted Maternally expressed gene1 (Meg1) in maize [8] is both necessary and sufficient for the establishment and differentiation of the endosperm nutrient transfer cells located at the mother:seed interface. Consistent with these findings, Meg1 also regulates maternal nutrient uptake, sucrose partitioning, and seed biomass yield. In addition, we generated an imprinted and nonimprinted synthetic Meg1 (synMeg1) dosage series whereby increased dosage and absence of imprinting both resulted in an unequal investment of maternal resources into the endosperm. These findings highlight dosage regulation by genomic imprinting as being critical for maintaining a balanced distribution of maternal nutrients to filial tissues in plants, as in mammals. However, unlike in mammals, Meg1 is a maternally expressed imprinted gene that surprisingly acts to promote rather than restrict nutrient allocation to the offspring.

Highlights

► Imprinted Meg1 is necessary and sufficient for maize transfer cell development ► Meg1 regulates maternal nutrient translocation into the seed and seed biomass yield ► Meg1 dosage is critical for balanced nutrient distribution within the seed ► Imprinting is a potential constraining factor in crop seed improvement

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