Plant Science

Support Shoots, Repress Roots

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Science  25 Sep 2009:
Vol. 325, Issue 5948, pp. 1601
DOI: 10.1126/science.325_1601d
CREDIT: GRIGG ET AL., CURR. BIOL. 19, 1485 (2009)

Most flowering plants grow at both ends. The growth of leaves and flowers derives from the shoot apical meristem, and the growth of roots derives from the root meristem. Although the meristems, which are clusters of undifferentiated stem cells, have much in common, they generate different tissues and structures. Studying the small mustard plant Arabidopsis, Grigg et al. offer an analysis of how the meristems come to differ. Two homeodomain proteins, PHABULOSA (PHB) and PHAVOLUTA (PHV), support shoot apical meristem development and repress root meristem development. PHB and PHV are regionally repressed by a microRNA pathway, and this enables development of the root meristem. This regulatory network is in place as early as the 32-cell stage of embryonic development, when the root stem cells begin to emerge. Repression of PHB and PHV seems to be particularly important for establishing the quiescent center cells of the root meristem.

Curr. Biol. 19, 1485 (2009).

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