Age-related loss of rooting capability in Arabidopsis thaliana and its reversal by peptides containing the Arg-Gly-Asp (RGD) motif
Department of Plant Biology, University of Alcalá, ES-28871, Alcalá de Henares, Madrid, Spain 1Present address: Barberet & Blanc S.A., Camino Viejo, 205 ES-30890, Puerto Lumbreras, Murcia, Spain. Physiologia Plantarum
(Impact Factor: 3.14).
05/2002; 114(4):601-607. DOI: 10.1034/j.1399-3054.2002.1140414.x
We describe here an experimental system to study the age-related decline of adventitious root formation in Arabidopsis thaliana L. (Heynh), ecotype Landsberg erecta (Ler). The system is based on the different rooting capacity of hypocotyls from de-rooted juvenile (12-day-old) and adult (26-day-old) plants. Hypocotyls from de-rooted juvenile plants rooted readily within a week of culture, and the rooting process was not dependent on exogenous auxin. In contrast, hypocotyls from de-rooted adult plants rooted poorly and only after longer periods of time. Exogenously applied auxin had no effect on rooting of hypocotyls from de-rooted adult plants. Rooting capacity, although correlated with the transition to flowering, did not depend on this transition. Root induction declined in a similar manner when the transition to flowering was delayed, either genetically with the fve mutant or physiologically with short days. The results showed that rooting of hypocotyls from de-rooted adult plants depended on the effect of peptides containing the RGD motif. Both the percentage of rooting and the number of roots were largely increased when the hypocotyls were treated transiently with the RGD peptide. The effect of the RGD peptide was a necessary, but not sufficient, condition for rooting of hypocotyls from de-rooted adult plants.
Available from: PubMed Central
- "A protein with GTP-binding motifs, involved in regulating cell wall biosynthesis and actin organization, was associated with adventitious root formation and other processes requiring directional cell expansion, such as lateral root formation or the growth of root hairs, in poplar (Xu et al., 2012). In addition to the inductive effects of auxin, the effect of the RGD peptides is a necessary condition for rooting of hypocotyls from de-rooted adult plants of Arabidopsis (Díaz-Sala et al., 2002). These results provide support for the hypothesis that cell wall–plasma membrane–cytoskeleton interactions of specific cells could be involved in the rooting capacity of adult plants, perhaps by the stabilization of differentiation, cell division, and morphogenesis. "
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ABSTRACT: Cellular plasticity refers, among others, to the capability of differentiated cells to switch the differentiation process and acquire new fates. One way by which plant cell plasticity is manifested is through de novo regeneration of organs from somatic differentiated cells in an ectopic location. However, switching the developmental program of adult cells prior to organ regeneration is difficult in many plant species, especially in forest tree species. In these species, a decline in the capacity to regenerate shoots, roots, or embryos from somatic differentiated cells is associated with tree age and maturation. The decline in the ability to form adventitious roots from stem cuttings is one of the most dramatic effects of maturation, and has been the subject of investigations on the basic nature of the process. Cell fate switches, both in plants and animals, are characterized by remarkable changes in the pattern of gene expression, as cells switch from the characteristic expression pattern of a somatic cell to a new one directing a new developmental pathway. Therefore, determining the way by which cells reset their gene expression pattern is crucial to understand cellular plasticity. The presence of specific cellular signaling pathways or tissue-specific factors underlying the establishment, maintenance, and redirection of gene expression patterns in the tissues involved in adventitious root formation could be crucial for cell fate switch and for the control of age-dependent cellular plasticity.
Available from: Arthur G Fett-Neto
- "Another useful model to study AR and the loss of rooting capacity is Arabidopsis thaliana. Using de-rooted hypocotyls of young (12 day old) and adult (26 day old) plants of the Landsberg ecotype, it was shown that AR was much slower in adult de-rooted plants and that endogenous polar auxin transport (evaluated with NPA application) was crucial for AR (Díaz-Sala et al., 2002). These authors also showed that rooting was not dependent on phase shift to reproductive phase, although a correlation was observed. "
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ABSTRACT: Adventitious rooting (AR) is a multifactorial response leading to new roots at the base of stem cuttings, and the establishment of a complete and autonomous plant. AR has two main phases: a) induction, with a requirement for higher auxin concentration; b) formation, inhibited by high auxin and in which anatomical changes take place. The first stages of this process in severed organs necessarily include wounding and water stress responses which may trigger hormonal changes that contribute to reprogram target cells that are competent to respond to rooting stimuli. At severance, the roles of jasmonate and abscisic acid are critical for wound response and perhaps sink strength establishment, although their negative roles on the cell cycle may inhibit root induction. Strigolactones may also inhibit AR. A reduced cytokinin concentration in cuttings results from the separation of the root system, whose tips are a relevant source of these root induction inhibitors. The combined increased accumulation of basipetally transported auxins from the shoot apex at the cutting base is often sufficient for AR in easy-to-root species. The role of peroxidases and phenolic compounds in auxin catabolism may be critical at these early stages right after wounding. The events leading to AR strongly depend on mother plant nutritional status, both in terms of minerals and carbohydrates, as well as on sink establishment at cutting bases. Auxins play a central role in AR. Auxin transporters control auxin canalization to target cells. There, auxins act primarily through selective proteolysis and cell wall loosening, via their receptor proteins TIR1 and ABP1. A complex microRNA circuitry is involved in the control of auxin response factors essential for gene expression in AR. After root establishment, new hormonal controls take place, with auxins being required at lower concentrations for root meristem maintenance and cytokinins needed for root tissue differentiation.
Available from: Azamal Husen
- "In this study, both rooting and sprouting by coppice-shoot cuttings declined with increasing age of donor plants. Decreased rooting potential of cuttings due to aging/or maturity of donor plants has been previously reported in several plant species        which may be due to decreased sensitivity of aging tissues to rooting promoters or accumulation of inhibitory substances for rooting and/or decrease in the content of endogenous auxins responsible for root formation by cuttings   . "
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