The effects of auxin and cytokinin on light dependent carotenoid synthesis were studied in callus cultures derived from Ricinus endosperm tissue. Chloroplasts differentiate when calli are grown in the light in the presence of cytokinin and auxin. When cultures are transferred to an auxin-free medium, chromoplast differentiation is initiated, i.e. rhodoxanthin accumulates whereas lutein and chlo...

Changes in levels of abscisic acid (ABA) and cytokinin activity in the xylem sap of willow (Salix viminalis, L.) were followed throughout two growth cycles.Growth in spring was preceded by decreasing levels of ABA and an increase in cytokinin activity. The onset of dormancy was associated with low levels of cytokinins and high contents of ABA. A second peak of ABA was found in July which was no...

Cytokinins influence many aspects of plant growth and development. The current model for cytokinin signaling is a multi-step phosphorelay similar to the prokaryotic two-component systems that are used in responses to environmental stimuli. Recently, progress has been made in improving our understanding of the molecular mechanism that underlies cytokinin signaling. Molecular and genetic analyses...

The phytohormones cytokinin and auxin orchestrate the root meristem development in angiosperms by determining embryonic bipolarity. Ferns, having the most basal euphyllophyte root, form neither bipolar embryos nor permanent embryonic primary roots but rather an adventitious root system. This raises the questions of how auxin and cytokinin govern fern root system architecture and whether this ca...

In higher plants, inorganic nitrogen has crucial effects on growth and development, providing cellular components and modulating gene expression. To date, not only nitrogen assimilatory genes but also a substantial number of genes with other functions have been shown to be selectively regulated by the availability of nitrogen. In terms of the communicating substance(s) between root and shoot, a...

UNLABELLED Endophytic bacteria are harmless in most plant species; and known to boost the growth and development of the host plants probably by secreting growth hormones. The isolation, identification and screening of endophytic bacteria for the plant growth regulators like cytokinin are needed to get the leads for their applications in agriculture sector. We describe the isolation and identifi...

The Sho gene from Petunia hybrida encodes an enzyme responsible for the synthesis of plant cytokinins. The 3' region of the Sho gene contains a promoter in the opposite orientation that produces a partially overlapping antisense transcript. Although Sho expression varies significantly in individual cell types, the sense and antisense transcript levels maintain a stable ratio in most tissue type...

BACKGROUND Although cytokinins have been known for decades to play important roles in the regulation of plant growth and development, our knowledge of the regulatory mechanism of endogenous content of specific cytokinins remains limited. METHODOLOGY/PRINCIPAL FINDINGS Here, we characterized two SOB five-like (SOFL) genes, AtSOFL1 and AtSOFL2, in Arabidopsis (Arabidopsis thaliana) and showed t...

The diverse plasticity of plant architecture is largely determined by shoot branching. Shoot branching is an event regulated by multiple environmental, developmental and hormonal stimuli through triggering lateral bud response. After perceiving these signals, the lateral buds will respond and make a decision on whether to grow out. TCP transcriptional factors, BRC1/TB1/FC1, were previously prov...

Cytokinins are distributed through the vascular system and trigger responses of target cells via receptor-mediated signal transduction. Perception and transduction of the signal can occur at the plasma membrane or in the cytosol. The signal is terminated by the action of extra- or intracellular cytokinin oxidases. While radiotracer studies have been used to study transport and metabolism of cyt...