Crosstalk between Auxin, Cytokinins, and Sugars in the Plant Cell Cycle

Abstract

Plant meristems are utilization sinks, in which cell division activity governs sink strength. However, the molecular mechanisms by which cell division activity and sink strength are adjusted to a plant's developmental program in its environmental setting are not well understood. Mitogenic hormonal as well as metabolic signals drive and modulate the cell cycle, but a coherent idea of how this is accomplished, is still missing. Auxin and cytokinins are known as endogenous mitogens whose concentrations and timing, however, can be externally affected. Although the sites and mechanisms of signal interaction in cell cycle control have not yet been unravelled, crosstalk of sugar and phytohormone signals could be localized to several biochemical levels. At the expression level of cell cycle control genes, like cyclins, Cdks, and others, synergistic but also antagonistic interactions could be demonstrated. Another level of crosstalk is that of signal generation or modulation. Cytokinins affect the activity of extracellular invertases and hexose-uptake carriers and thus impinge on an intracellular sugar signal. With tobacco BY-2 cells, a coordinated control of cell cycle activity at both regulatory levels could be shown. Comparison of the results obtained with the root cell-representing BY-2 cells with literature data from shoot tissues or green cell cultures of Arabidopsis and Chenopodium suggests opposed and tissue-specific regulatory patterns of mitogenic signals and signal crosstalk in root and shoot meristems.

New Insights into Roles of Cell Wall Invertase in Early Seed Development Revealed by Comprehensive Spatial and Temporal Expression Patterns of GhCWIN1 in Cotton

“…By cross talking with hormones, invertase-mediated sugar signaling may regulate the expression of cell cycle control genes, thereby modulating chromosomal duplication and cell cycles (Hartig and Beck, 2006), as proposed for embryonic cell division in legumes (Weber et al, 2005) and maize (Rijavec et al, 2009;LeClere et al, 2010). Consistent with this is the strong expression of GhCWIN1 and AtCWIN4 transcripts in globular embryos of cotton ( Fig.…”

Whole Genome Analysis of Gene Expression Reveals Coordinated Activation of Signaling and Metabolic Pathways during Pollen-Pistil Interactions in Arabidopsis

“…S1C; Supplemental File S2). Cross talk of cytokinin and auxin in the regulation of cell division is another well-known process, namely in specific cellcycle transitions (Hartig and Beck, 2006). This cross talk seems to be important for the regulation of expression and activity of CdkA at the G2/M transition (Sorrell et al, 2001) and to induce the expression of the D3 cyclins at the G1/S transition (Riou-Khamlichi et al, 1999).…”

Osmotic stress stimulates shoot organogenesis in callus of rice (Oryza sativa L.) via auxin signaling and carbohydrate metabolism regulation

“…Many studies discussed the possible role of phytohormones, sugar sensing, and osmotic stress during shoot organogenesis, respectively Hartig and Beck 2006;Pernisová et al 2009). However, no reports have elucidated the underlying mechanism among these factors.…”