Submitted to: Maydica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/1/2005
Publication Date: 12/1/2005
Citation: Lunde, C., Hake, S.C. 2005. Florets and Rosettes: Meristem Genes in Maize and Arabidopsis. Maydica. 50:451-458. Interpretive Summary: Spectacular variety in plant form and adaptation can be seen throughout the Angiosperms. Even basal plants display complex morphologies as a result of their genetic programs. Both the shoot and root arise from a fixed number of stem cells in the respective shoot and root apical meristems. These meristems are controlled by gene networks that in turn are influenced by events that occur externally - a necessity due to the sessile nature of plants. Recent studies suggest that the key regulatory pathways controlling maintenance of stem cell populations and their transition into organs have largely been conserved since the divergence of monocots and dicots, 134 million years ago (Wikström et al., 2001). The regulation of these pathways may help explain differences in morphology between these two major plant subdivisions. Maize has comparatively large meristems and initiates a series of inflorescence meristems before producing determinant floral meristems. This expanded developmental program, along with abundant genetic resources, makes maize an ideal model for meristem studies. Several pathways have been elucidated in Arabidopsis that control organ generation and meristem maintenance. Maize orthologues have been identified that are conserved in protein sequence and function. Examples of these shared networks include those of the clavata and knox pathways. Evolution of unique structures particular to the grasses, such as the spikelet, has also occurred. In this case, no Arabidopsis orthologs have been identified, rather different genes have been co-opted for unique functions. Such examples are the adaptation of ERF proteins for spikelet meristem determinacy. We present a comparison of the regulation of key meristem pathways in the dicot model plant, Arabidopsis, and maize.
Technical Abstract: Maize and Arabidopsis genes that regulate inflorescence development are contrasted. Genes that regulate meristem size are often conserved, whereas genes that regulate meristem identity in maize do not have readily identifiable orthologs in Arabidopsis.