Self perpetuation of the shoot meristem is essential for the repetitive initiation of shoot structures during plant development. In Arabidopsis shoot meristem maintenance is disrupted by recessive mutations in the WUSCHEL (WUS) gene. The defect is evident at all developmental stages and is restricted to shoot and floral meristems, whereas the root meristem is not affected. wus mutants fail to p...

Nodules on the roots of legume plants host nitrogen-fixing Rhizobium bacteria. Several lines of evidence indicate that nodules are evolutionarily related to roots. We determined whether developmental control of the Medicago truncatula nodule meristem bears resemblance to that in root meristems through analyses of root meristem-expressed PLETHORA genes. In nodules, MtPLETHORA 1 and 2 are prefere...

Plants differ from most animals in their ability to initiate new cycles of growth and development, which relies on the establishment and activity of branch meristems harboring new stem cell niches. In seed plants, this is achieved by axillary meristems, which are established in the axil of each leaf base and develop into lateral branches. Here, we describe the initial processes of Arabidopsis t...

The shoot apical meristem is the ultimate source of the cells that constitute the entire aboveground portion of the plant body. In Arabidopsis thaliana, meristem maintenance is regulated by the negative feedback loop of WUSCHEL-CLAVATA (WUS-CLV). Although CLV-like genes, such as FLORAL ORGAN NUMBER1 (FON1) and FON2, have been shown to be involved in maintenance of the reproductive meristems in ...

The timing of the switch from vegetative to reproductive development is crucial for species survival. The plant-specific transcription factor and meristem identity regulator LEAFY (LFY) controls this switch in Arabidopsis, in part via the direct activation of two other meristem identity genes, APETALA1 (AP1) and CAULIFLOWER (CAL). We recently identified five new direct LFY targets as candidates...

BACKGROUND AND AIMS In angiosperms, the shoot apical meristem produces a shoot system composed of stems, leaves and axillary buds. Podostemoideae, one of three subfamilies of the river-weed family Podostemaceae, have a unique 'shoot' that lacks a shoot apical meristem and is composed only of leaves. Tristichoideae have been interpreted to have a shoot apical meristem, although its branching pat...

We report two new recessive mutations in Arabidopsis, mgoun1 and mgoun2 which cause a reduction in the number of leaves and floral organs, larger meristems and fasciation of the inflorescence stem. Although meristem structure is affected in the mutants, we provide evidence that its overall organisation is normal, as shown by the expression patterns of two meristem markers. Microscopical analyse...

Plant architecture consists of repeating units called phytomers, each containing an internode, leaf and axillary meristem. The formation of boundaries within the phytomer is necessary to differentiate and separate these three components, otherwise some will grow at the expense of others. The microRNA-targeted SBP-box transcription factor tasselsheath4 (tsh4) plays an essential role in establish...

Root elongation requires cell divisions in the meristematic zone and cell elongation in the elongation zone. The boundary between dividing and elongating cells is called the transition zone. In the meristem zone, initial cells are continuously dividing, but on the basal side of the meristem cells exit the meristem through the transition zone and enter in the elongation zone, where they stop div...

The shoot meristem is a proliferating, changing cell population yet displays a stable organization. Recent studies have addressed how signaling processes coordinate the behaviour of shoot meristem cells.