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![Root excision increases adventitious root formation in Arabidopsis . A, The number of adventitious roots was determined in the intact or root-excised hypocotyls (n = 20–30). B, Adventitious root formation on intact (left) and excised (right) cleared hypocotyls is shown after 7 d. Arrow points to an adventitious root in the intact hypocotyl, and arrowhead points to site of excision. Bar = 5 mm. [See online article for color version of this figure.]](profile/Gloria-Muday/publication/236912603/figure/fig1/AS:340793215733776@1458262842844/Root-excision-increases-adventitious-root-formation-in-Arabidopsis-A-The-number-of.png)
Root excision increases adventitious root formation in Arabidopsis . A, The number of adventitious roots was determined in the intact or root-excised hypocotyls (n = 20–30). B, Adventitious root formation on intact (left) and excised (right) cleared hypocotyls is shown after 7 d. Arrow points to an adventitious root in the intact hypocotyl, and arrowhead points to site of excision. Bar = 5 mm. [See online article for color version of this figure.]
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Adventitious roots emerge from aerial plant tissues and the induction of these roots is essential for clonal propagation of agriculturally important plant species. This process has received extensive study in horticultural species, but much less focus in genetically tractable model species. We have explored the role of auxin transport in this proce...
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Context 1
... s -1 ) with and without ex- cision of the basal half of the shoot and root system (termed root-excised hypocotyls). Intact hypocotyls form zero to one adventitious root per plant located in the middle of the hypocotyl by the eighth day after transfer to high light, while excision substantially in- creased the number of adventitious roots formed (Fig. 1). Excision had the advantage of reproducibly inducing adventitious roots at a position 1 to 2 mm above the site of excision, so molecular events associated with root formation could be examined at this position prior to the first detectable adventitious ...
Context 2
... induction of adventitious roots in intact versus root- excised hypocotyls to determine whether the response to auxin was changed by excision. Treatment of 5-d- old root-excised and intact hypocotyls with IAA in- creased the number of adventitious roots relative to untreated hypocotyls at concentrations ranging from 0.1 to 25 mM IAA (Supplemental Fig. S1). This result is consistent with increases in adventitious roots on intact Arabidopsis hypocotyls at IAA concentrations between 0.1 and 10 mM ( Wilmoth et al., 2005) and in derooted juvenile hypocotyls ( Correa et al., 2012) but differs from the report that IAA or indole-butyric acid did not stimulate adventitious rooting in mature ...
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Adventitious roots (ARs) are formed de novo during post-embryonic development from non-root tissues, in processes that are highly dependent on environmental inputs. Whole root excision from young seedlings has been previously used as a model to study adventitious root formation in Arabidopsis thaliana hypocotyls. To identify novel regulators of adv...
The ability for cut tissues to join together and form a chimeric organism is a remarkable property of many plants, however, grafting is poorly characterized at the molecular level. To better understand this process we monitored genome-wide temporal and spatial gene expression changes in grafted Arabidopsis thaliana hypocotyls. Tissues above and bel...
Citations
... To verify whether adventitious root primordia formation on the stems initiate during cold treatment, we used the A. alpina lines carrying the synthetic DR5 promoter fused to the reporter gene GUS (Figure 3) (Vayssières et al., 2020). Reporter plants transformed with pDR5::GUS have been used in several species to monitor developing adventitious roots following auxin accumulation (Inukai et al., 2005;Sukumar et al., 2013;Rasmussen et al., 2015). In A. alpina stems, GUS expression under pDR5 during cold exposure was reduced in comparison to before cold exposure suggesting a decreased GUS transcription in cold as described before (Figure 3; Supplementary Figure 3) (Lee et al., 2005). ...
Arctic alpine species experience extended periods of cold and unpredictable conditions during flowering. Thus, often, alpine plants use both sexual and asexual means of reproduction to maximize fitness and ensure reproductive success. We used the arctic alpine perennial Arabis alpina to explore the role of prolonged cold exposure on adventitious rooting. We exposed plants to 4°C for different durations and scored the presence of adventitious roots on the main stem and axillary branches. Our physiological studies demonstrated the presence of adventitious roots after 21 weeks at 4°C saturating the effect of cold on this process. Notably, adventitious roots on the main stem developing in specific internodes allowed us to identify the gene regulatory network involved in the formation of adventitious roots in cold using transcriptomics. These data and histological studies indicated that adventitious roots in A. alpina stems initiate during cold exposure and emerge after plants experience growth promoting conditions. While the initiation of adventitious root was not associated with changes of DR5 auxin response and free endogenous auxin level in the stems, the emergence of the adventitious root primordia was. Using the transcriptomic data, we discerned the sequential hormone responses occurring in various stages of adventitious root formation and identified supplementary pathways putatively involved in adventitious root emergence, such as glucosinolate metabolism. Together, our results highlight the role of low temperature during clonal growth in alpine plants and provide insights on the molecular mechanisms involved at distinct stages of adventitious rooting.
... In Arabidopsis, auxin transport from the shoot-apex to the basal stem is required for AR development. Auxin transport mutants (ABCB19, AUX1-7, PIN1-1, PIN3-3, and PIN7) show reduced AR growth (Sukumar et al., 2013). A grafting approach was employed to test whether a graft between WT (N. ...
4-Coumarate-CoA Ligase (4CL) is an important enzyme in the phenylpropanoid biosynthesis pathway. Multiple 4CLs are identified in Ocimum species; however, their in planta functions remain enigmatic. In this study, we independently overexpressed three Ok4CL isoforms from Ocimum kilimandscharicum (Ok4CL7, -11, and -15) in Nicotiana benthamiana. Interestingly, Ok4CL11 overexpression (OE) caused a rootless or reduced root growth phenotype, whereas overexpression of Ok4CL15 produced normal adventitious root (AR) growth. Ok4CL11 overexpression in N. benthamiana resulted in upregulation of genes involved in flavonoid biosynthesis and associated glycosyltransferases accompanied by accumulation of specific flavonoid-glycosides (kaempferol-3-rhamnoside, kaempferol-3,7-O-bis-alpha-l-rhamnoside [K3,7R], and quercetin-3-O-rutinoside) that possibly reduced auxin levels in plants, and such effects were not seen for Ok4CL7 and -15. Docking analysis suggested that auxin transporters (PINs/LAXs) have higher binding affinity to these specific flavonoid-glycosides, and thus could disrupt auxin transport/signaling, which cumulatively resulted in a rootless phenotype. Reduced auxin levels, increased K3,7R in the middle and basal stem sections, and grafting experiments (intra and inter-species) indicated a disruption of auxin transport by K3,7R and its negative effect on AR development. Supplementation of flavonoids and the specific glycosides accumulated by Ok4CL11-OE to the wild-type N. benthamiana explants delayed the AR emergence and also inhibited AR growth. While overexpression of all three Ok4CLs increased lignin accumulation, flavonoids, and their specific glycosides were accumulated only in Ok4CL11-OE lines. In summary, our study reveals unique indirect function of Ok4CL11 to increase specific flavonoids and their glycosides, which are negative regulators of root growth, likely involved in inhibition of auxin transport and signaling.
... However, in routine commercial grafting and cutting programs, IBA (Indole 3butyric acid) is the most commonly used auxin instead of IAA, which is an efficient promoter of AR in many species (Da Costa et al., 2013). The next crucial stage of AR initiation in hypocotyl or stem cuttings of several species is polar auxin transport (Sukumar et al., 2013). In most plant species, three classes of carriers and transporters present at the plasma membrane contribute as auxin influx and efflux carriers that are transcriptionally and posttranscriptionally regulated and mediate cell-to-cell auxin transport (Armengot et al., 2016). ...
... Some particular sites have been discovered recently, including COP9 SINGALOSOME SUBUNIT4, AUXIN RESPONSE1, SHORT HYPOCOTYL2 (SHY2), and RUB-CONJUGATING ENZIME1 (RCE1) (Pacurar et al., 2017). Auxin efflux carriers like ABCB19 and PIN1 that are involved in auxin accumulation at the base of the stem are major contributors to AR formation, but when loss-of-function mutant genes abcb19À1 and pin1À1 are present, drastic effects on AR number in mutant phenotypes have been observed (Sukumar et al., 2013). AR formation studies have also revealed the active involvement of some major signaling molecules, including INDOLE-3-ACETIC ACID INDUCIBLE28 (IAA28), CRANE (IAA18), WOODEN LEG, ARABIDOPSIS RESPONSE REGULATORS1 (ARR1), ARR10, and ARR12 molecules in petiolar tissues as revealed by gain-of-function mutants (crane-2 and solitary root-1 [slr-1]) (BustilloÀAvendañ o et al., 2018). ...
... ASA2 encoding anthranilate synthase is essential for producing tryptophan, a primary precursor in the auxin biosynthesis pathway 63 . Alteration of ABCB19 auxin transporter gene expression in Arabidopsis varies auxin transportation, affecting both adventitious 64 and lateral root 65 formation. Seven DNB genes were involved in carbohydrate metabolism, namely sucrose phosphate synthase 1F (SPS1F), two of trehalase1 (TRE1), pectin methylesterase 3 (PME3), pectinesterase inhibitor 39 (PEI39), non-specific phospholipase C3 (NPC3), and chitinase-like protein (CTL). ...
Cassava storage roots (SR) are an important source of food energy and raw material for a wide range of applications. Understanding SR initiation and the associated regulation is critical to boosting tuber yield in cassava. Decades of transcriptome studies have identified key regulators relevant to SR formation, transcriptional regulation and sugar metabolism. However, there remain uncertainties over the roles of the regulators in modulating the onset of SR development owing to the limitation of the widely applied differential gene expression analysis. Here, we aimed to investigate the regulation underlying the transition from fibrous (FR) to SR based on Dynamic Network Biomarker (DNB) analysis. Gene expression analysis during cassava root initiation showed the transition period to SR happened in FR during 8 weeks after planting (FR8). Ninety-nine DNB genes associated with SR initiation and development were identified. Interestingly, the role of trehalose metabolism, especially trehalase1 (TRE1), in modulating metabolites abundance and coordinating regulatory signaling and carbon substrate availability via the connection of transcriptional regulation and sugar metabolism was highlighted. The results agree with the associated DNB characters of TRE1 reported in other transcriptome studies of cassava SR initiation and Attre1 loss of function in literature. The findings help fill the knowledge gap regarding the regulation underlying cassava SR initiation.
... In the latter culture condition, the enhancing effect of 2,3-MDPU in the presence of exogenous IBA is at least partially lost ( Figure 3A-C). We can tentatively explain this result by assuming a locally exerted disruptive effect of NPA that (i) blocks the ABCB19 transporter that has been shown to be responsible for the formation of local auxin maxima necessary for adventitious root formation [65], or (ii) might mimic the effect of cytokinin [66]. These effects are in addition to the inhibition of cytokinin dehydrogenase/oxygenase activity by 2,3-MDPU, as indicated by both docking simulations and inhibition of ZmCKX1, so that the local auxin/cytokinin crosstalk is probably highly unbalanced in favor of endogenous cytokinins. ...
Adventitious rooting is a process of postembryonic organogenesis strongly affected by endogenous and exogenous factors. Although adventitious rooting has been exploited in vegetative propagation programs for many plant species, it is a bottleneck for vegetative multiplication of difficult-to-root species, such as many woody species. The purpose of this research was to understand how N,N′-bis-(2,3-methylenedioxyphenyl)urea could exert its already reported adventitious rooting adjuvant activity, starting from the widely accepted knowledge that adventitious rooting is a hormonally tuned progressive process. Here, by using specific in vitro bioassays, histological analyses, molecular docking simulations and in vitro enzymatic bioassays, we have demonstrated that this urea derivative does not interfere with polar auxin transport; it inhibits cytokinin oxidase/dehydrogenase (CKX); and, possibly, it interacts with the apoplastic portion of the auxin receptor ABP1. As a consequence of this dual binding capacity, the lifespan of endogenous cytokinins could be locally increased and, at the same time, auxin signaling could be favored. This combination of effects could lead to a cell fate transition, which, in turn, could result in increased adventitious rooting.
... AtMDR1 is mainly expressed in root and shoot apices, which promotes root and hypcotyl enlongation by media the distribution of auxin (Sidler, et al. 1998). AtMDR11 is highly homologous to AtMDR1, and has the function of enhancing adventitious root formation (Sukumar, et al. 2013). Both AtMDR1 and AtMDR11 are function as an auxin e ux transporter in cells. ...
Key message OsMDR4 is an ABC transporter which localized to plasma membrane and mainly expressed in root to mediate the Cd absorption in rice. Abstract Cadmium(Cd) is one of heavy metals which threaten crop security production. The transporters in root are key factors involved in metal absorption. However, there are a large amount of Cd transporter in rice root remains uncharted. Here, we report a member of multidrug resistance protein OsMDR4 mediating the Cd absorption in rice. Heterologous overexpressing OsMDR4 in yeast increased the sensitivity to Cd treatment and Cd content in the cells. Consistantly, the Cd concentration of the mdr4 mutants is lower than that in wild type, in both root and shoot. In addition, the Vmax values of Cd uptake in mdr4 mutants are much lower than that of wild type by uptake kinetics analysis. OsMDR4 is mainly expressed in epidermis and root hairs of rice roots during seedling stage, and flower organs at flowering stage. Further more, the expression level of OsMDR4 in seedling root is induced by Cd supply. As a transporter OsMDR4 is localized to plasma membrane of rice cells. Taken together, we characterized a novel Cd transporter OsMDR4 which had a significant contribution in Cd influx into root.
... This regulation has described accelerated growth in the root zone. When root architecture is modified by MEL action, nutrient and water uptake is promoted [31]. Adequate mineral supply and proper water uptake ultimately leads to increased yield and plant capacity to produce biomass. ...
... In addition, application at the lowest doses (1 µM) of both OMP and MEL were the most effective in increasing yield-by 1.8 and 2.2 times, respectively-with respect to the control, with a 100-fold lower dose. root architecture is modified by MEL action, nutrient and water uptake is promoted [31]. Adequate mineral supply and proper water uptake ultimately leads to increased yield and plant capacity to produce biomass. ...
Climate change has prompted agri-food systems to explore new strategies for improving the production of crops in a sustainable manner. This includes green bean, the most important legume in the world for its nutritional value. The use of omeprazole (OMP) and melatonin (MEL) has been proposed as innovative strategy for crop improvement when they are applied as biostimulants. However, although their role in the growth of several species has been studied, the results in photosynthetic efficiency parameters are still scarce. Therefore, the objective of the present study was to evaluate the effect of foliar application of OMP and MEL on biomass, yield, SPAD values, leaf chlorophyll fluorescence (Fv/Fm), photochemical quenching (qP), non-photochemical quenching (NPQ), quantum yield of photosystem II (PhiPSII), and electron transport rate (ETR) in bean plants. Treatments were applied separately at doses of 1, 10, and 100 µM, plus a control without application. The results obtained indicate that OMP and MEL were able to increase biomass; yield; SPAD values; and qP, Fv/Fm, and PhiPSII coefficients. Finally, it is concluded that foliar application of OMP and MEL at a dose of 1 and 10 µM can increase photosynthetic efficiency and decrease photoinhibition, which is reflected in higher biomass accumulation and yield in green bean plants cv. Strike.
... Next is 'initiation', a process that takes place within 2-4 days of injury and, in addition to a cell fate transition, cell division occurs in response to growth hormone, resulting in the formation of a domeshaped root primordium with multiple cell layers. During cell division, many cell cycle-related genes are activated [58][59][60][61] Studies have shown that ERF115 acts as a CK signaling mechanism for AR initiation by activating CK, and ERF115 can be activated by JA transcription, inhibiting AR initiation in a ninja dependent and independent manner [19,62]. At the same time, cell division may be inhibited by solanum lactone. ...
Plant regeneration is a self-repair of the plant body in response to adverse conditions or damaged structures, and root regeneration allows the plant body to better adapt to its environment by supplementing the roots’ structure. Previous research has shown that adventitious roots can be made to occur from scratch in two ways. Studies that simulate adventitious root regeneration through natural conditions allow the regeneration process to be broadly divided into three stages: the perception of early signals, the massive accumulation of auxin, and the transformation of cell fate. The strength of regeneration, in turn, is influenced by wounding, stress, hormones, etc. This study mainly reviews the molecular mechanisms of de novo adventitious roots and discusses how the environment, hormones, and its own development in Arabidopsis thaliana.
... The function of auxin signaling and transport in adventitious root formation have been reported in different species [2,[52][53][54]. Inhibitors of plant auxin transport, such as NPA, were shown to delay and inhibit adventitious root formation [32,48,49,[55][56][57]. ...
The mechanisms underlying the de novo regeneration of adventitious roots are still poorly understood, particularly in trees. We developed a system for studying adventitious rooting (AR) at physiological and molecular levels using leaves excised from chestnut microshoots of the same genotype but with two distinct ontogenetic origins that differ in rooting competence. Leaves were treated with auxin and N-1-naphthyl-phthalamic acid (NPA), an inhibitor of auxin polar transport (PAT). The physiological effects were investigated by recording rooting rates and the number and quality of the roots. Molecular responses were examined by localizing and monitoring the changes in the expression of CsSCL1, an auxin-inducible gene in juvenile and mature shoots during AR. The rooting response of leaves was ontogenetic-stage dependent and similar to that of the donor microshoots. Initiation of root primordia and root development were inhibited by application of NPA, although its effect depended on the timing of application. CsSCL1 was upregulated by auxin only in rooting-competent leaves during the novo root organogenesis, and the expression was reduced by NPA. The inhibitory effect on gene expression was detected during the reprograming of rooting competent cells towards root initials in response to auxin, indicating that PAT-mediated upregulation of CsSCL1 is required in the initial steps of AR in chestnut leaves. The localized expression of CsSCL1 in the quiescent center (QC) also suggests a role for this gene in the maintenance of meristematic competence and root radial patterning.
... The function of auxin signalling and transport in adventitious root formation have been reported in different species [2,[53][54][55]. Inhibitors of plant auxin transport, such as NPA, were shown to delay and inhibit adventitious root formation [32,48,49,[56][57][58]. ...
The mechanisms underlying the de novo regeneration of adventitious roots are still poorly understood, particularly in trees. In this study, we developed a system for studying different modulators of adventitious rooting (AR) at physiological and molecular levels by using for the first time leaves excised from chestnut microshoots. The rooting response of leaves was ontogenetic-stage dependent, and similar to that of the original microshoots. Initiation of root primordia and root development were inhibited by application of N-1-naphthyl-phthalamic acid (NPA), although the effect of this inhibitor of auxin polar transport (PAT) depended on the timing of application. Expression of CsSCL1, an auxin-inducible gene in juvenile and mature shoots during AR, was upregulated by auxin only in rooting-competent leaves during the novo root organogenesis and the expression was reduced by the NPA treatment. This inhibitory effect on gene expression was detected during reprograming of rooting competent cells towards root initials in response to auxin, indicating that PAT-mediated upregulation of CsSCL1 is required in the initial steps of AR in chestnut leaves. The localized expression of CsSCL1 in the quiescent center (QC) also suggests a role for this gene in the maintenance of meristematic competence and root radial patterning.
