One in the Same, Almost

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Science  26 Nov 2010:
Vol. 330, Issue 6008, pp. 1157
DOI: 10.1126/science.330.6008.1157-c

Although many flowering plants reproduce by sexual reproduction, some plants evade the complexities of chromosome reduction, dispersion of gametes, and fertilization by undergoing a type of asexual reproduction called apomixis. Such plants produce a seed, but that seed carries the same diploid genome as its one parent and can generate a new plant. Apomixis has been suggested to be a deregulated form of sexual reproduction. Garcia-Aguilar et al. have now analyzed the molecular mechanisms that distinguish the sexual reproduction pathway found in maize from the apomictic pathway found in a wild relative of maize. The results implicate an alteration in DNA methylation pathways, which normally impose repressive marks on the chromatin. When certain methyltransferases expressed during sexual reproduction function poorly, or are deleted, the chromatin takes on a state that is more permissive of transcription, and a developmental program resembling apomixis is seen. Thus, chromatin modifications and their subsequent effects on gene transcription are involved in determining whether a plant reproduces sexually or by apomixis.

Plant Cell 10.1105/tpc.109.072181 (2010).

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