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R Waites

Publications and source records attributed to R Waites.

5 recordsLinked to original sources
PubMed2001

Control of cell fate in plant meristems.

In contrast to animals, plants do not stop to initiate organs with the end of embryogenesis. Instead, most of the growth and development of higher plants will take place during later phases following germination of the seed. Plant development depends on the activity of two meristems, the root meristem and the shoot apical meristem (SAM), that are located at opposite ends of the plant embryo. These meristems serve as a source of pluripotent stem cells and, in case of the SAM, provide a centre for repetitive organ initiation. In order to maintain the SAM throughout plant life, the cells that are lost from the meristem through organ initiation and differentiation have to be replaced from the stem cell population. In this paper, we will discuss recent results indicating that the fate of stem cells in plant meristems is controlled by directional signalling systems.

Animals↗
PubMed2001

The Handlebars gene is required with Phantastica for dorsoventral asymmetry of organs and for stem cell activity in Antirrhinum.

In angiosperms, individual lateral organs and whole flowers may develop asymmetrically along their dorsoventral axes. Dorsoventral asymmetry of Antirrhinum leaves requires activity of the Phantastica gene and other factors acting redundantly with it. We describe the effects of a mutation in the Handlebars gene, identified as an enhancer of the phantastica mutant phenotype. Genetic analysis suggests that Handlebars functions redundantly with Phantastica to promote dorsal fate in lateral organs and to maintain activity of stem cells within shoot apical meristems. Handlebars appears dispensable in vegetative development but is needed for asymmetry of petals along the dorsoventral axis of the flower as a whole. This suggests that common mechanisms may control dorsoventral asymmetry in lateral organ primordia and in floral meristems.

Cotyledon↗
PubMed1998

The PHANTASTICA gene encodes a MYB transcription factor involved in growth and dorsoventrality of lateral organs in Antirrhinum.

The organs of a higher plant show two fundamental axes of asymmetry: proximodistal and dorsoventral. Dorsoventrality in leaves, bracts, and petal lobes of Antirrhinum majus requires activity of the PHANTASTICA (PHAN) gene. Conditional mutants revealed that PHAN is also required for earlier elaboration of the proximodistal axis. PHAN was isolated and shown to encode a MYB transcription factor homolog. PHAN mRNA is first detected in organ initials before primordium initiation. The structure and expression pattern of PHAN, together with its requirement in two key features of organ development, are consistent with a role in specifying lateral organ identity as distinct from that of the stem or meristem. PHAN also appears to maintain meristem activity in a non-cell-autonomous manner.

Alleles↗
PubMed1998

Early events in leaf development.

Morphological studies of early events in leaf development have been hindered by the lack of stereotypic patterns of cell division and markers for cell identity. However, molecular genetic analysis, particularly in maize, has begun to suggest the mechanisms which partition meristematic cells into a leaf primordium, define regional identities within the primordium and direct localised growth which leads to outgrowth and flattening of the leaf. Therefore, the leaf may provide a model for pattern formation applicable to other parts of the plant.

Meristem↗