Inhibition Of Adventitious Root Formation Research Articles

Temperature-sensitive splicing defects in Arabidopsis mitochondria caused by mutations in the ROOT PRIMORDIUM DEFECTIVE 1 gene.

Group II introns in plant organelles have lost splicing autonomy and require the assistance of nuclear-encoded trans-factors whose roles remain to be elucidated. These factors can be mono- or poly-specific with respect to the number of introns whose splicing they facilitate. Poly-acting splicing factors are often essential and their genetic identification may benefit from the use of conditional mutations. Temperature-sensitive (TS) mutations in the ROOT PRIMORDIUM DEFECTIVE 1 (RPD1) gene were initially selected for their inhibitory effect on root formation in Arabidopsis. Further analysis revealed that RPD1 encodes a mitochondria-targeted RNA-binding protein family member, suggesting a role in mitochondrial gene expression and making its role in root formation enigmatic. We analysed the function of RPD1 and found that it is required for the removal of 9 mitochondrial group II introns and that the identified TS mutations affect the splicing function of RPD1. These results support that the inhibition of adventitious root formation at non-permissive temperature results from a reduction in RPD1 activity and thus mitochondrial activity. We further show that RPD1 physically associates in vivo with the introns whose splicing it facilitates. Preliminary mapping indicates that RPD1 may not bind to the same regions within all of its intron targets, suggesting potential variability in its influence on splicing activation.

Trehalose alleviates the inhibition of adventitious root formation caused by drought stress in cucumber through regulating ROS metabolism and activating trehalose and plant hormone biosynthesis

Trehalose (Tre) plays a vital role in response to drought stress in plants but its regulatory mechanism remains unclear. Here, this study explores the mechanism of re-regulated drought tolerance during cucumber adventitious root formation. Our results indicate that 2 mM Tre displays remarkable drought alleviation in the aspect of root number, root length, fresh weight, and dry weight. Under drought stress, Tre could inhibit greatly the MDA, H2O2, and O2− accumulation, enhance obviously the activities of SOD, POD, and CAT enzymes and up-regulate significantly the transcript levels of SOD, POD, and CAT genes. Furthermore, Tre treatment also promotes Tre metabolism during drought stress: significantly increases starch and Tre contents and decreases glucose content, the biosynthesis enzymatic activity of the Tre metabolic pathway including TPS and TPP are enhanced and the activity of degradation enzyme THL is decreased, and corresponding genes TPS1, TPS2, TPPA, and TPPB are up-regulated. Tre significantly reversed the decrease caused by PEG in IAA, ethylene, ABA, and BR contents and the increase caused by PEG in GA3 and KT contents. Collectively, Tre appears to be the effective treatment in counteracting the negative effects of drought stress during adventitious root formation by regulating ROS, Tre metabolisms and plant hormones.

Strigolactone regulates adventitious root formation via the MdSMXL7-MdWRKY6-MdBRC1 signaling cascade in apple.

Propagation through stem cuttings is a popular method worldwide for species such as fruit tree rootstocks and forest trees. Adventitious root (AR) formation from stem cuttings is crucial for effective and successful clonal propagation of apple rootstocks. Strigolactones (SLs) are newly identified hormones involved in AR formation. However, the regulatory mechanisms underpinning this process remain elusive. In the present study, weighted gene co-expression network analysis, as well as rooting assays using stable transgenic apple materials, revealed that MdBRC1 served as a key gene in the inhibition of AR formation by SLs. We have demonstrated that MdSMXL7 and MdWRKY6 synergistically regulated MdBRC1 expression, depending on the interactions of MdSMXL7 and MdWRKY6 at the protein level downstream of SLs as well as the direct promoter binding on MdBRC1 by MdWRKY6. Furthermore, biochemical studies and genetic analysis revealed that MdBRC1 inhibited AR formation by triggering the expression of MdGH3.1 in a transcriptional activation pathway. Finally, the present study not only proposes a component, MdWRKY6, that enables MdSMXL7 to regulate MdBRC1 during the process of SL-controlled AR formation in apple, but also provides prospective target genes to enhance AR formation capacity using CRISPR (i.e. clustered regularly interspaced short palindromic repeats) technology, particularly in woody plants.

Integrated multi-omics analysis uncovers roles of mdm-miR164b-MdORE1 in strigolactone-mediated inhibition of adventitious root formation in apple.

Apple is one of the most important fruit crops in temperate regions and largely relies on cutting propagation. Adventitious root formation is crucial for the success of cutting propagation. Strigolactones have been reported to function in rooting of woody plants. In this study, we determined that strigolactones have inhibitory effects on adventitious root formation in apple. Transcriptome analysis identified 12 051 differentially expressed genes over the course of adventitious root initiation, with functions related to organogenesis, cell wall biogenesis or plant development. Further analysis indicated that strigolactones might inhibit adventitious root formation through repressing two core hub genes, MdLAC3 and MdORE1. Combining small RNA and degradome sequencing, as well as dual-luciferase sensor assays, we identified and validated three negatively correlated miRNA-mRNA pairs, including mdm-miR397-MdLAC3 and mdm-miR164a/b-MdORE1. Overexpression of mdm-miR164b and silencing MdORE1 exhibited enhanced adventitious root formation in tobacco and apple, respectively. Finally, we verified the role of mdm-miR164b-MdORE1 in strigolactone-mediated repression of rooting ability. Overall, the identified comprehensive regulatory network in apple not only provides insight into strigolactone-mediated adventitious root formation in other woody plants, but also points to a potential strategy for genetic improvement of rooting capacity in woody plants.

Different miRNAs and hormones are involved in PEG-induced inhibition of adventitious root formation in apple

• PEG inhibited AR formation in GL-3 apple cuttings. • Lower IAA and higher ABA, JA-me, and ZR content lead to the inhibition of ARs. • 32 known miRNAs belonging to 22 families and 60 novel miRNAs were found to be differentially expressed. • A total of 81 target genes of known miRNAs and 62 targets of novel miRNAs were identified using degradome sequencing. In apples, adventitious root (AR) formation plays a crucial role in the life cycle, but drought stress limits this process. Multiple hormones and miRNAs play key roles in regulating ARs under drought conditions, but they are lacking in GL-3 apple clones. Therefore, to identify physiological and molecular changes behind the phenotype, GL-3 apple cuttings were treated with 6% polyethylene glycol (PEG) during the activation, induction, initiation, and emergence stages of AR formation and compared with a PEG-free control. Anatomical analysis indicates that 6% PEG treatment delays AR primordia formation and produces fewer thin ARs than control plants by decreasing the indole-3-acetic acid (IAA) endogenous content and promoting the abscisic acid (ABA), methyl jasmonate (JA-me), and zeatin riboside (ZR) content at all time points. Furthermore, 32 known miRNAs belonging to 22 families and 60 novel miRNAs were found to be differentially expressed. A total of 81 target genes of known miRNAs and 62 targets of novel miRNAs were identified using degradome sequencing. The known miRNA targets were classified into 50 GO terms. In biological processes, various terms related to the response to water deprivation; salt, heat, and cold stress; abscisic acid-activated signaling pathways; and so on, were observed. The KEGG analysis indicates 20 pathways from which plant hormone signal transduction, ribosomes, etc., were the most enriched. Further analyses indicated that miRNAs (miR167b, miR393g, and miR477a) related to IAA, ABA, and JA were induced; various stress-responsive miRNAs (miR171c, miR169o, miR159a, miR10979, and miR167a) were also promoted; and cell division and development-related miRNAs (miR396a and miR482a) were repressed by 6% PEG treatment. These results indicate that AR formation is an intricate biological process in apples under stressed conditions regulated by various hormones, related miRNAs, and target genes. This study delivers new information about the underlying regulatory mechanisms of AR formation in GL-3 and other plants.

Regulation of Root Development and Architecture by Strigolactones under Optimal and Nutrient Deficiency Conditions.

Strigolactones (SLs) constitute a group of plant hormones which are involved in multiple aspects of plant growth and development. Beside their role in shoot and root development and plant architecture in general, SLs are also involved in plant responses to nutrient deficiency by promoting interactions with symbiotic organisms and via promotion of root elongation. Recent observations on the cross talk between SLs and other hormones demonstrate that the inhibition of adventitious root formation by ethylene is independent of SLs. Additionally, it was shown that root exposure to SLs leads to the accumulation of secondary metabolites, such as flavonols or antioxidants. These data suggest pleiotropic effects of SLs, that influence root development. The discovery that the commonly used synthetic SL analogue racGR24 might also mimic the function of other plant growth regulators, such as karrikins, has led us to consider the previously published publications under the new aspects. This review summarizes present knowledge about the function of SLs in shaping root systems under optimal and nutrient deficiency conditions. Results which appear inconsistent with the various aspects of root development are singled out.

Caffeic acid inhibits in vitro rooting in mung bean [Vigna radiata (L.) Wilczek] hypocotyls by inducing oxidative stress

Caffeic acid (CA), which is ubiquitously present in plants, is a potent phytotoxin affecting plant growth and physiology. The aim of our study was to investigate whether CA-induced inhibition of adventitious root formation (ARF) in mung bean {Vigna radiata (L.) Wilczek [Phaseolus aureus Roxb.]} involves the induction of conventional stress responses. The effect of CA (0-1000 μM) on ARF in mung bean was determined by measuring the generation of reactive oxygen species (ROS) in terms of malondialdehyde and hydrogen peroxide (H 2 O 2 ) content, root oxidizability and changes in levels of antioxidant enzymes. Our results show that CA significantly enhanced MDA content, indicating severe lipid peroxidation, and increased H 2 O 2 accumulation and root oxidizability in the lower rooted hypocotylar region (LRHR) of mung bean, thereby inducing oxidative stress and cellular damage. In response to CA, there was a significant upregulation in the activities of scavenging enzymes, such as superoxide dismutase, ascorbate peroxidase, guaiacol peroxidase, catalase and glutathione reductase, in LRHRs of mung bean. Based on these results, we conclude that CA inhibits ARF in mung bean hypocotyls by inducing ROS-generated oxidative stress and upregulating the activities of antioxidant enzymes.

The Heme Oxygenase/Carbon Monoxide System Is Involved in the Auxin-Induced Cucumber Adventitious Rooting Process

Indole acetic acid (IAA) is an important regulator of adventitious rooting via the activation of complex signaling cascades. In animals, carbon monoxide (CO), mainly generated by heme oxygenases (HOs), is a significant modulator of inflammatory reactions, affecting cell proliferation and the production of growth factors. In this report, we show that treatment with the auxin transport inhibitor naphthylphthalamic acid prevented auxin-mediated induction of adventitious rooting and also decreased the activity of HO and its by-product CO content. The application of IAA, HO-1 activator/CO donor hematin, or CO aqueous solution was able to alleviate the IAA depletion-induced inhibition of adventitious root formation. Meanwhile, IAA or hematin treatment rapidly activated HO activity or HO-1 protein expression, and CO content was also enhanced. The application of the HO-1-specific inhibitor zinc protoporphyrin IX (ZnPPIX) could inhibit the above IAA and hematin responses. CO aqueous solution treatment was able to ameliorate the ZnPPIX-induced inhibition of adventitious rooting. Molecular evidence further showed that ZnPPIX mimicked the effects of naphthylphthalamic acid on the inhibition of adventitious rooting, the down-regulation of one DnaJ-like gene (CSDNAJ-1), and two calcium-dependent protein kinase genes (CSCDPK1 and CSCDPK5). Application of CO aqueous solution not only dose-dependently blocked IAA depletion-induced inhibition of adventitious rooting but also enhanced endogenous CO content and up-regulated CSDNAJ-1 and CSCDPK1/5 transcripts. Together, we provided pharmacological, physiological, and molecular evidence that auxin rapidly activates HO activity and that the product of HO action, CO, then triggers the signal transduction events that lead to the auxin responses of adventitious root formation in cucumber (Cucumis sativus).

A trans-zeatin riboside in root xylem sap negatively regulates adventitious root formation on cucumber hypocotyls.

Shoot cultures of cucumber were used to analyse the roles of root-derived substances in adventitious root formation on hypocotyl tissues. Xylem sap collected from the roots of squash had a strong inhibitory effect on the formation of hypocotyl adventitious roots. Double-solvent extraction followed by fractionation with both normal and reverse phase column chromatographies and analysis by liquid chromatography/tandem mass spectrometry identified trans-zeatin riboside (ZR) as the primary suppressor of adventitious root formation. ZR was the predominant cytokinin present in the xylem sap, occurring at a concentration of 2x10(-8 )M. Application of ZR at concentrations from 3.16x10(-9) M effected inhibition of adventitious root formation. These results suggest that ZR transported from roots via xylem sap may act as an endogenous suppressor of hypocotyl adventitious root formation in planta.

Abscisic acid and Ethrel abolish the inhibition of adventitious root formation of paclobutrazol-treated bean primary leaf cuttings

Paclobutrazol (PB), a triazole growth retardant and an inhibitor of gibberellin biosynthesis, reduced at 17 μM concentration the adventitious root formation of bean primary leaf cuttings. Treatments with 5 μM ABA or 4 μM Ethrel, an ethylenereleasing compound, restored the rooting of PB-treated cuttings. Ethylene production and the content of the precursor 1-aminocyclopropane-l-carboxylic acid (ACC) were enhanced in root-forming tissues of PB-treated petioles 48 h after ABA application. The effect of ABA could be abolished by 10 μM CoCl2, an inhibitor of ACC oxidase. Thus, ABA might stimulate rooting through its effect on ethylene release. 2 mM silver thiosulphate, an inhibitor of ethylene action, decreased the rooting of PB-treated cuttings similarly to Co2+, but failed to negate the ABA effect. These data indicate that the effect of PB on rhizogenesis is not associated directly with the inhibition of the biosynthesis of gibberellins

Inhibition of Adventitious Root Formation in Phaseolus vulgaris L. Primary Leaf Cuttings by the Presence of the Proximal Pulvinus

Journal Article Inhibition of Adventitious Root Formation in Phaseolus vulgaris L. Primary Leaf Cuttings by the Presence of the Proximal Pulvinus Get access S. HEWITT, S. HEWITT Botany Department, The UniversityGlasgow GI2 8QQ Search for other works by this author on: Oxford Academic PubMed Google Scholar J. R. HILLMAN J. R. HILLMAN Botany Department, The UniversityGlasgow GI2 8QQ Search for other works by this author on: Oxford Academic PubMed Google Scholar Annals of Botany, Volume 48, Issue 4, October 1981, Pages 569–572, https://doi.org/10.1093/oxfordjournals.aob.a086162 Published: 01 October 1981 Article history Accepted: 25 May 1981 Published: 01 October 1981

Light dependent promotion and inhibition of adventitious root formation by gibberellic acid

Cuttings from plants of Pisum sativum L. cv. "Alaska" which had been grown at an irradiance of 16 W m(-2) formed a higher number of roots than cuttings from plants grown at 38 W m(-2). (Irradiance during the rooting period always 16 W m(-2).) High concentrations of gibberellic acid (GA3) inhibited rooting in cuttings from both types of stock plants. Low concentrations (10(-9)-10(-6) M) of GA3 were without effect in cuttings from plants irradiated with 38 W m(-2), but promoted rooting when the stock plants had been grown at 16 W m(-2).

Action de la 2-thiouracile sur la rhizogen�se dans les boutures de plantules �tiol�es de tomate

1. 2-Thiouracil inhibits hypocotyl growth, adventitious root formation and growth of adventitious roots in cuttings of etiolated tomato seedlings. 2. The inhibition of the growth of hypocotyl was reversed totally by uracil and cytosin, but only partially by orotic acid and thymine. 3. The inhibition of the growth of adventitious roots was reversed by orotic acid, uracil and cytosine, but not by thymine. 4. The inhibition of adventitious root formation was reversed neither by orotic acid nor by uracil, cytosine, or thymine. 5. A hypothesis based on data in the literature is proposed to explain this latest results.