The jasmonates are well studied in the context of plant defence but increasingly are also recognised as playing roles in development. In many systems, jasmonates antagonise the effects of cytokinins. The aim of the present work was to elucidate interactions between methyl jasmonate and cytokinin (benzyladenine) in regulating growth of zucchini (Cucurbita pepo L., cv. Cocozelle, var. Tripolis) c...

Cytokinins are involved in key developmental processes in rice (Oryza sativa), including the regulation of cell proliferation and grain yield. However, the in vivo action of histidine kinases (OsHks), putative cytokinin receptors, in rice cytokinin signaling remains elusive. This study examined the function and characteristics of OsHk3, 4 and 6 in rice. OsHk6 was highly sensitive to isopentenyl...

In angiosperms, after the floral transition, the inflorescence meristem produces floral meristems (FMs). Determinate growth of FMs produces flowers of a particular size and form. This determinate growth requires specification of floral organs and termination of stem-cell divisions. Establishment of the FM and specification of outer whorl organs (sepals and petals) requires the floral homeotic g...

Strains of Escherichia coli that express two different cytokinin receptors of Arabidopsis thaliana, CRE1/AHK4 and AHK3, were used to study the relative sensitivity of these receptors to various cytokinins. Both receptors were most sensitive to the bases of the isoprenoid-type cytokinins trans-zeatin and isopentenyladenine but differed significantly in the recognition of other cytokinin compound...

The plant hormone cytokinin is implicated in the control of root architecture and development, including legume root nodulation. Gonzalez-Rizzo et al. (pages 2680–2693) identified a Medicago truncatula homolog of Arabidopsis, CYTOKININ RESPONSE1 (CRE1), which encodes a cytokinin receptor histidine kinase, and made use of RNA interference of Mt CRE1 to investigate the role of cytokinin in the no...

The plant hormone cytokinin is implicated in the control of root architecture and development, including legume root nodulation. Gonzalez-Rizzo et al. (pages 2680–2693) identified a Medicago truncatula homolog of Arabidopsis, CYTOKININ RESPONSE1 (CRE1), which encodes a cytokinin receptor histidine kinase, and made use of RNA interference of Mt CRE1 to investigate the role of cytokinin in the no...

We have isolated 20 cDNA clones for which the corresponding mRNAs accumulate 2- to 20-fold within 4 hr of cytokinin addition to cytokinin-starved soybean suspension cultures. These changes in mRNA levels precede the greening and cell growth induced by cytokinin in this system. Treatment with cycloheximide before cytokinin addition enhances the accumulation of these messages. In addition, the ab...

Cytokinins are plant hormones that play critical roles in growth and development. In Arabidopsis, the transcriptional response to cytokinin is regulated by action of type-B Arabidopsis response regulators (ARRs). Although central elements in the cytokinin signal transduction pathway have been identified, mechanisms controlling output remain to be elucidated. Here we demonstrate that a family of...

The phytohormones auxin and cytokinin are key regulators of plant development, and both regulate almost all aspects of plant growth and development. Communication between auxin-cytokinin signaling pathways has been the subject of intense research. However, few studies have focused specifically on the development of the early gynoecium. We have recently discovered that cytokinin signaling plays ...

Understanding how hormones and genes interact to coordinate plant growth is a major challenge in developmental biology. The activities of auxin, ethylene, and cytokinin depend on cellular context and exhibit either synergistic or antagonistic interactions. Here we use experimentation and network construction to elucidate the role of the interaction of the POLARIS peptide (PLS) and the auxin eff...