Mom's in Charge

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Science  10 Feb 2012:
Vol. 335, Issue 6069, pp. 636
DOI: 10.1126/science.335.6069.636-c

Imprinting is a genetic mechanism that directs an offspring to use only one copy of a parental gene. Typically, this occurs through the directed expression of an allele from only one parent. In the mammalian placenta, imprinting ensures proper nutrient allocation to the developing offspring. Costa et al. investigated whether this was also the case in the endosperm, the nutritive accessory tissue found in the seeds of flowering plants. In maize plants, the imprinted gene Maternally expressed gene1 (Meg1), which encodes a small peptide known to control cell differentiation in plants, regulated nutrient allocation and affected embryo growth. Meg1 promoted the development and differentiation of the endosperm nutrient transfer tissue, which is responsible for the uptake and partitioning of sugars within the seed. In this system, imprinting was necessary for fine-balancing nutrient allocation from the maternal tissue to both the embryo and endosperm. These findings suggest that, similar to their roles in the mammalian placenta, imprinted genes function in the plant endosperm to control the nourishment of the embryo.

Curr. Biol. 22, 160 (2012).

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