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Danny Geelen - One of the best experts on this subject based on the ideXlab platform.
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Ethylene Controls Adventitious Root Initiation Sites in Arabidopsis Hypocotyls Independently of Strigolactones
Journal of Plant Growth Regulation, 2017Co-Authors: Amanda Rasmussen, Thomas Depaepe, Filip Vandenbussche, Dominique Van Der Straeten, Yuming Hu, François-didier Boyer, Danny GeelenAbstract:Adventitious Root formation is essential for cutting propagation of diverse species; however, until recently little was known about its regulation. Strigolactones and ethylene have both been shown to inhibit Adventitious Roots and it has been suggested that ethylene interacts with strigolactones in Root hair elongation. We have investigated the interaction between strigolactones and ethylene in regulating Adventitious Root formation in intact seedlings of Arabidopsis thaliana. We used strigolactone mutants together with 1-aminocyclopropane-1-carboxylic acid (ACC) (ethylene precursor) treatments and ethylene mutants together with GR24 (strigolactone agonist) treatments. Importantly, we conducted a detailed mapping of Adventitious Root initiation along the hypocotyl and measured ethylene production in strigolactone mutants. ACC treatments resulted in a slight increase in Adventitious Root formation at low doses and a decrease at higher doses, in both wild-type and strigolactone mutants. Furthermore, the distribution of Adventitious Roots dramatically changed to the top third of the hypocotyl in a dose-dependent manner with ACC treatments in both wild-type and strigolactone mutants. The ethylene mutants all responded to treatments with GR24. Wild type and max4 (strigolactone-deficient mutant) produced the same amount of ethylene, while emanation from max2 (strigolactone-insensitive mutant) was lower. We conclude that strigolactones and ethylene act largely independently in regulating Adventitious Root formation with ethylene controlling the distribution of Root initiation sites. This role for ethylene may have implications for flood response because both ethylene and Adventitious Root development are crucial for flood tolerance.
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Adventitious Root induction in Arabidopsis thaliana as a model for in vitro Root organogenesis.
Methods in molecular biology (Clifton N.J.), 2012Co-Authors: Inge Verstraeten, Tom Beeckman, Danny GeelenAbstract:Adventitious Root formation, the development of Roots on non-Root tissue (e.g. leaves, hypocotyls and stems) is a critical step during micropropagation. Although Root induction treatments are routinely used for a large number of species micropropagated in vitro as well as for in vivo cuttings, the mechanisms controlling Adventitious Rooting are still poorly understood. Researchers attempt to gain better insight into the molecular aspects by studying Adventitious Rooting in Arabidopsis thaliana. The existing assay involves etiolation of seedlings and measurements of de novo formed Roots on the elongated hypocotyl. The etiolated hypocotyls express a novel auxin-controlled signal transduction pathway in which auxin response factors (ARFs), microRNAs and environmental conditions that drive Adventitious Rooting are integrated. An alternative assay makes use of so-called thin cell layers (TCL), excised strips of cells from the inflorescence stem of Arabidopsis thaliana. However, both the etiolated seedling system and the TCL assay are only distantly related to industrial Rooting processes in which Roots are induced on adult stem tissue. Here, we describe an Adventitious Root induction system that uses segments of the inflorescence stems of Arabidopsis thaliana, which have a histological structure similar to cuttings or in vitro micropropagated shoots. The system allows multiple treatments with chemicals as well as the evaluation of different environmental conditions on a large number of explants. It is therefore suitable for high throughput chemical screenings and experiments that require numerous data points for statistical analysis. Using this assay, the Adventitious Root induction capacity of classical auxins was evaluated and a differential response to the different auxins could be demonstrated. NAA, IBA and IAA stimulated Adventitious Rooting on the stem segment, whereas 2,4-D and picloram did not. Light conditions profoundly influenced the Root induction capacity of the auxins. Additionally to the environmental control of Adventitious Root formation, we also investigated the spatial and temporal aspects of stem-based Adventitious Root organogenesis. To determine the cells involved in de novo Root initiation on the adult stems, we adopted scanning electron microscopy, which allows the visualization of the auxin responsive stem tissue. Using this technique, direct (without callus interface) and indirect (with intermediate callus phase) organogenesis was readily distinguished. The described micro-stem segment system is also suitable for other non-woody species and it is a valuable tool to perform fast evaluations of different treatments to study Adventitious Root induction.
Eric J W Visser - One of the best experts on this subject based on the ideXlab platform.
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environmental factors constraining Adventitious Root formation during flooding of solanum dulcamara
Functional Plant Biology, 2017Co-Authors: Qian Bo-zhang, Jannah W T Boerakker, Daniek Bosch, Heidrun Huber, Hans De Kroon, Eric J W VisserAbstract:Flooding is a compound stress, imposing strong limitations on plant development. The expression of adaptive traits that alleviate flooding stress may be constrained if floodwater levels are too deep. For instance, Adventitious Root outgrowth is typically less profound in completely submerged plants than in partially submerged plants, suggesting additional constraints in full submergence. As both oxygen and carbohydrates are typically limited resources under submergence, we tested the effects of oxygen concentration in the floodwater and carbohydrate status of the plants on flooding-induced Adventitious Root formation in Solanum dulcamara L. Partially submerged plants continued to form Adventitious Roots in low-oxygen floodwater, whereas completely submerged plants developed hardly any Roots, even in floodwater with twice the ambient oxygen concentration. This suggests that contact with the atmosphere, enabling internal aeration, is much more important to optimal Adventitious Root formation than floodwater oxygen concentrations. If plants were depleted of carbohydrates before flooding, Adventitious Root formation in partial submergence was poor, unless high light was provided. Thus, either stored or newly produced carbohydrates can fuel Adventitious Root formation. These results imply that the impact of an environmental stress factor like flooding on plant performance may strongly depend on the interplay with other environmental factors.
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life cycle stage and water depth affect flooding induced Adventitious Root formation in the terrestrial species solanum dulcamara
Annals of Botany, 2015Co-Authors: Qian Bo-zhang, Eric J W Visser, Hans De Kroon, Heidrun HuberAbstract:Background and Aims Flooding can occur at any stage of the life cycle of a plant, but often adaptive responses of plants are only studied at a single developmental stage. It may be anticipated that juvenile plants may respond differently from mature plants, as the amount of stored resources may differ and morphological changes can be constrained. Moreover, different water depths may require different strategies to cope with the flooding stress, the expression of which may also depend on developmental stage. This study investigated whether flooding-induced Adventitious Root formation and plant growth were affected by flooding depth in Solanum dulcamara plants at different developmental stages. Methods Juvenile plants without pre-formed Adventitious Root primordia and mature plants with primordia were subjected to shallow flooding or deep flooding for 5 weeks. Plant growth and the timing of Adventitious Root formation were monitored during the flooding treatments. Key Results Adventitious Root formation in response to shallow flooding was significantly constrained in juvenile S. dulcamara plants compared with mature plants, and was delayed by deep flooding compared with shallow flooding. Complete submergence suppressed Adventitious Root formation until up to 2 weeks after shoots restored contact with the atmosphere. Independent of developmental stage, a strong positive correlation was found between Adventitious Root formation and total biomass accumulation during shallow flooding. Conclusions The potential to deploy an escape strategy (i.e. Adventitious Root formation) may change throughout a plant’s life cycle, and is largely dependent on flooding depth. Adaptive responses at a given stage of the life cycle thus do not necessarily predict how the plant responds to flooding in another growth stage. As variation in Adventitious Root formation also correlates with finally attained biomass, this variation may form the basis for variation in resistance to shallow flooding among plants.
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Regulatory role of auxin in Adventitious Root formation in two species of Rumex, differing in their sensitivity to waterlogging
Physiologia Plantarum, 1995Co-Authors: Eric J W Visser, Clementine J. Heijink, Karen J. G. M. Van Hout, Laurentius A. C. J. Voesenek, G. W. M. Barendse, Cornelis W. P. M. BlomAbstract:Adventitious Rooting in Rumex plants, in which the Root systems were in hypoxic conditions, differed considerably between two species. R. palustris, a species from frequently flooded river forelands, developed a large number of Adventitious Roots during hypoxia, whereas Adventitious Root formation was poor in R. thyrsiflorus, a species from seldom flooded dykes and river dunes. Adventitious Rooting could also be evoked in aerated plants of both species by application of auxin (1-naphthaleneacetic acid or indoleacetic acid) to the leaves. The response to auxin was dose-dependent, but even high auxin doses could not stimulate R. thyrsiflorus to produce as many Adventitious Roots as R. palustris. Consequently, the difference between the species in the amount of Adventitious Root formation was probably genetically determined, and not a result of a different response to auxin. A prerequisite for hypoxia-induced Adventitious Root formation is the basipetal transport of auxin within the shoot, as specific inhibition of this transport by N-1-naphthylphthalamic acid severely decreased the number of Roots in hypoxia-treated plants. It is suggested that hypoxia of the Root system causes stagnation of auxin transport in the Root system. This can lead to an accumulation of auxin at the base of the shoot rosette, resulting in Adventitious Root formation.
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Adventitious Root formation as an adaptive response to environmental stress
1993Co-Authors: C.w.p.m. Blom, L.a.c.j. Voesenek, W.m.h.g. Engelaar, Eric J W VisserAbstract:First International Symposium on the Biology of Adventitious Root Formation, Dallas, USA. United States Department of Agriculture. Forest Service, General Technical Report NC-154,
Heidrun Huber - One of the best experts on this subject based on the ideXlab platform.
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environmental factors constraining Adventitious Root formation during flooding of solanum dulcamara
Functional Plant Biology, 2017Co-Authors: Qian Bo-zhang, Jannah W T Boerakker, Daniek Bosch, Heidrun Huber, Hans De Kroon, Eric J W VisserAbstract:Flooding is a compound stress, imposing strong limitations on plant development. The expression of adaptive traits that alleviate flooding stress may be constrained if floodwater levels are too deep. For instance, Adventitious Root outgrowth is typically less profound in completely submerged plants than in partially submerged plants, suggesting additional constraints in full submergence. As both oxygen and carbohydrates are typically limited resources under submergence, we tested the effects of oxygen concentration in the floodwater and carbohydrate status of the plants on flooding-induced Adventitious Root formation in Solanum dulcamara L. Partially submerged plants continued to form Adventitious Roots in low-oxygen floodwater, whereas completely submerged plants developed hardly any Roots, even in floodwater with twice the ambient oxygen concentration. This suggests that contact with the atmosphere, enabling internal aeration, is much more important to optimal Adventitious Root formation than floodwater oxygen concentrations. If plants were depleted of carbohydrates before flooding, Adventitious Root formation in partial submergence was poor, unless high light was provided. Thus, either stored or newly produced carbohydrates can fuel Adventitious Root formation. These results imply that the impact of an environmental stress factor like flooding on plant performance may strongly depend on the interplay with other environmental factors.
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life cycle stage and water depth affect flooding induced Adventitious Root formation in the terrestrial species solanum dulcamara
Annals of Botany, 2015Co-Authors: Qian Bo-zhang, Eric J W Visser, Hans De Kroon, Heidrun HuberAbstract:Background and Aims Flooding can occur at any stage of the life cycle of a plant, but often adaptive responses of plants are only studied at a single developmental stage. It may be anticipated that juvenile plants may respond differently from mature plants, as the amount of stored resources may differ and morphological changes can be constrained. Moreover, different water depths may require different strategies to cope with the flooding stress, the expression of which may also depend on developmental stage. This study investigated whether flooding-induced Adventitious Root formation and plant growth were affected by flooding depth in Solanum dulcamara plants at different developmental stages. Methods Juvenile plants without pre-formed Adventitious Root primordia and mature plants with primordia were subjected to shallow flooding or deep flooding for 5 weeks. Plant growth and the timing of Adventitious Root formation were monitored during the flooding treatments. Key Results Adventitious Root formation in response to shallow flooding was significantly constrained in juvenile S. dulcamara plants compared with mature plants, and was delayed by deep flooding compared with shallow flooding. Complete submergence suppressed Adventitious Root formation until up to 2 weeks after shoots restored contact with the atmosphere. Independent of developmental stage, a strong positive correlation was found between Adventitious Root formation and total biomass accumulation during shallow flooding. Conclusions The potential to deploy an escape strategy (i.e. Adventitious Root formation) may change throughout a plant’s life cycle, and is largely dependent on flooding depth. Adaptive responses at a given stage of the life cycle thus do not necessarily predict how the plant responds to flooding in another growth stage. As variation in Adventitious Root formation also correlates with finally attained biomass, this variation may form the basis for variation in resistance to shallow flooding among plants.
Qian Bo-zhang - One of the best experts on this subject based on the ideXlab platform.
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environmental factors constraining Adventitious Root formation during flooding of solanum dulcamara
Functional Plant Biology, 2017Co-Authors: Qian Bo-zhang, Jannah W T Boerakker, Daniek Bosch, Heidrun Huber, Hans De Kroon, Eric J W VisserAbstract:Flooding is a compound stress, imposing strong limitations on plant development. The expression of adaptive traits that alleviate flooding stress may be constrained if floodwater levels are too deep. For instance, Adventitious Root outgrowth is typically less profound in completely submerged plants than in partially submerged plants, suggesting additional constraints in full submergence. As both oxygen and carbohydrates are typically limited resources under submergence, we tested the effects of oxygen concentration in the floodwater and carbohydrate status of the plants on flooding-induced Adventitious Root formation in Solanum dulcamara L. Partially submerged plants continued to form Adventitious Roots in low-oxygen floodwater, whereas completely submerged plants developed hardly any Roots, even in floodwater with twice the ambient oxygen concentration. This suggests that contact with the atmosphere, enabling internal aeration, is much more important to optimal Adventitious Root formation than floodwater oxygen concentrations. If plants were depleted of carbohydrates before flooding, Adventitious Root formation in partial submergence was poor, unless high light was provided. Thus, either stored or newly produced carbohydrates can fuel Adventitious Root formation. These results imply that the impact of an environmental stress factor like flooding on plant performance may strongly depend on the interplay with other environmental factors.
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life cycle stage and water depth affect flooding induced Adventitious Root formation in the terrestrial species solanum dulcamara
Annals of Botany, 2015Co-Authors: Qian Bo-zhang, Eric J W Visser, Hans De Kroon, Heidrun HuberAbstract:Background and Aims Flooding can occur at any stage of the life cycle of a plant, but often adaptive responses of plants are only studied at a single developmental stage. It may be anticipated that juvenile plants may respond differently from mature plants, as the amount of stored resources may differ and morphological changes can be constrained. Moreover, different water depths may require different strategies to cope with the flooding stress, the expression of which may also depend on developmental stage. This study investigated whether flooding-induced Adventitious Root formation and plant growth were affected by flooding depth in Solanum dulcamara plants at different developmental stages. Methods Juvenile plants without pre-formed Adventitious Root primordia and mature plants with primordia were subjected to shallow flooding or deep flooding for 5 weeks. Plant growth and the timing of Adventitious Root formation were monitored during the flooding treatments. Key Results Adventitious Root formation in response to shallow flooding was significantly constrained in juvenile S. dulcamara plants compared with mature plants, and was delayed by deep flooding compared with shallow flooding. Complete submergence suppressed Adventitious Root formation until up to 2 weeks after shoots restored contact with the atmosphere. Independent of developmental stage, a strong positive correlation was found between Adventitious Root formation and total biomass accumulation during shallow flooding. Conclusions The potential to deploy an escape strategy (i.e. Adventitious Root formation) may change throughout a plant’s life cycle, and is largely dependent on flooding depth. Adaptive responses at a given stage of the life cycle thus do not necessarily predict how the plant responds to flooding in another growth stage. As variation in Adventitious Root formation also correlates with finally attained biomass, this variation may form the basis for variation in resistance to shallow flooding among plants.
Amanda Rasmussen - One of the best experts on this subject based on the ideXlab platform.
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Ethylene Controls Adventitious Root Initiation Sites in Arabidopsis Hypocotyls Independently of Strigolactones
Journal of Plant Growth Regulation, 2017Co-Authors: Amanda Rasmussen, Thomas Depaepe, Filip Vandenbussche, Dominique Van Der Straeten, Yuming Hu, François-didier Boyer, Danny GeelenAbstract:Adventitious Root formation is essential for cutting propagation of diverse species; however, until recently little was known about its regulation. Strigolactones and ethylene have both been shown to inhibit Adventitious Roots and it has been suggested that ethylene interacts with strigolactones in Root hair elongation. We have investigated the interaction between strigolactones and ethylene in regulating Adventitious Root formation in intact seedlings of Arabidopsis thaliana. We used strigolactone mutants together with 1-aminocyclopropane-1-carboxylic acid (ACC) (ethylene precursor) treatments and ethylene mutants together with GR24 (strigolactone agonist) treatments. Importantly, we conducted a detailed mapping of Adventitious Root initiation along the hypocotyl and measured ethylene production in strigolactone mutants. ACC treatments resulted in a slight increase in Adventitious Root formation at low doses and a decrease at higher doses, in both wild-type and strigolactone mutants. Furthermore, the distribution of Adventitious Roots dramatically changed to the top third of the hypocotyl in a dose-dependent manner with ACC treatments in both wild-type and strigolactone mutants. The ethylene mutants all responded to treatments with GR24. Wild type and max4 (strigolactone-deficient mutant) produced the same amount of ethylene, while emanation from max2 (strigolactone-insensitive mutant) was lower. We conclude that strigolactones and ethylene act largely independently in regulating Adventitious Root formation with ethylene controlling the distribution of Root initiation sites. This role for ethylene may have implications for flood response because both ethylene and Adventitious Root development are crucial for flood tolerance.
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Strigolactones inhibit Adventitious Root formation
2010Co-Authors: Amanda RasmussenAbstract:Adventitious Root formation from a non-Root tissue facilitates clonal propagation of elite plant varieties and is therefore central to many plant industries worldwide. However many plant species cannot be propagated in this way posing significant limitations particularly on the forestry and horticulture industries. Although clonal propagation has been used for centuries, we have only recently begun to understand the process of Adventitious Root formation at the genetic, molecular and biochemical levels. Adventitious Root initiation is regulated by many hormones including auxin and cytokinins. The research described in this thesis discovered a new function for strigolactones as a regulator of Adventitious Rooting. Strigolactones, known for their role in shoot branching, were clearly involved in the suppression of Adventitious Root initiation in two biological systems: pea stem cuttings and Arabidopsis seedling hypocotyls. The CYCB1:GUS marker together with microscopy of strigolactone mutants in both systems, established that strigolactones limit the size of the region in which Adventitious Roots can initiate (Rooting zone). There was no difference in the density of Adventitious Roots within the Rooting zone and there was no evidence of unfinished primordia within wild type and strigolactone mutant plants. To determine if strigolactones may play a wider role in plant development, pea and Arabidopsis strigolactone mutants were also screened for developmental phenotypes such as germination, intact primary Root growth and lateral Root branching, but only primary Root growth was affected and the phenotype was quite subtle. In order to understand how strigolactones function in concert with other hormones already known to be involved in Adventitious Rooting, the interactions of strigolactones with cytokinins and auxins were investigated. Arabidopsis cytokinin production and response mutants (ipt1 ipt5 ipt7 triple mutant and ahk3 ahk4 double mutant, respectively) responded to strigolactones and the strigolactone deficient mutants responded to cytokinin. These findings were supported by grafting studies between wild type and strigolactone response mutants in pea and suggest that cytokinins and strigolactones likely act independently. Because auxin is important in Adventitious Root formation, the interaction between strigolactone and auxin was investigated using the Arabidopsis 35S:YUCCA1 auxin overproducing mutant and also using treatments with different types of auxin. Fewer Adventitious Roots were formed in 35S:YUCCA1 after strigolactone treatments compared to the control treatments and the strigolactone mutants of both pea and Arabdidopsis generated more Adventitious Roots in response to auxin treatments. This suggests that strigolactone does not act upstream of auxin biosynthesis and that auxin does not act directly upstream of strigolactone biosynthesis. It is possible though that strigolactone inhibits auxin transport, at least locally, and thereby reduces the amount of auxin that can build up in the Rooting zone. Future research prompted by the data presented in this thesis should investigate a role for strigolactones in regulating auxin transport or also regulation of local auxin levels via conversion of IBA to IAA. Experimental reduction of strigolactone production in pea and Arabidopsis increased the number of Adventitious Roots that formed. Five ornamental species were also tested and Adventitious Rooting was improved by reduction of strigolactones in the species that were more difficult to Root. These results suggest that manipulation of strigolactones could be used to improve Adventitious Rooting of commercially important and difficult-to-Root species. Further research should test these theories and eventually this knowledge can be used to improve the cutting propagation of commercially important species.
