Adventitious Root Initiation Research Articles

Genome-wide analysis of the WOX gene family and function exploration of RhWOX331 in rose (R. 'The Fairy').

WOXs are a class of plant-specific transcription factors that play key roles in plant growth and stress responses. However, the mechanism by which WOXs influence adventitious root development in Rosa hybrida remains unclear. In this study, RcWOX gene family in rose was identified and phylogenetically analyzed using bioinformatics analysis. A total of 381 RcWOX gene members were localized on seven chromosomes except of nine members. The main cis-acting elements involved in hormonal, light, developmental, and abiotic stress responses were identified in the promoters of RcWOX genes, suggesting their regulation by these signals. Nine RhWOX genes had significant different expression during rooting process of rose. RhWOX331, RhWOX308, RhWOX318 were positive with the formation of rose roots. RhWOX331 was positively involved in the formation of adventitious root primordia, which gene coding a transcription factor localized in the nucleus. The HOX conserved domain in the protein contributed to the self-activating activity of RhWOX331. We obtained genetically modified Arabidopsis to validate the function of RhWOX331. Overexpression of RhWOX331 gene alleviated the inhibition of root length of A. thaliana primary roots by high concentration of IBA and NPA, and significantly increased the number of lateral roots on the primary roots, as well as the height of A. thaliana plants. Additionally, RhWOX331 promoted adventitious root formation in A. thaliana and mitigated hormonal inhibition by exogenous 6-BA, NPA, and GA3. The RhWOX331 promoter contained cis-acting elements such as ABRE, Box 4 and CGTCA-motif et.al. GUS activity analysis showed that the gene acted at the cotyledon attachment site. Taken together, these studies identified a significant expansion of the RcWOX gene family, inferred roles of certain branch members in adventitious root formation, elucidated the function of RhWOX331 in adventitious root initiation, and laid the foundation for further research on the function of WOX gene family in roses.

IBA and melatonin increase trigonelline and caffeine during the induction and initiation of adventitious roots in Coffea arabica L. cuttings

Caffeine and trigonelline are found in Coffea arabica, and show antioxidant roles and growth and development functions. However, there are no reports on trigonelline and caffeine in relation to coffee rooting. The aim was to evaluate the impact of application of indole-3-butyric acid (IBA) and melatonin on caffeine and trigonelline at different stages of adventitious rooting in cuttings. In addition, to study the correlation between these metabolites and H2O2, phenols, and antioxidant enzymes. Four treatments (Control, melatonin 21 µM (M21), melatonin 43 µM (M43), and IBA 7380 µM (IBA)) were used, with four replications. The growth and biochemical parameters of the antioxidant system were performed in induction, initiation, and extension rooting stages. Higher concentrations of trigonelline and caffeine quantified in the induction and initiation stages were positively correlated with higher percentage of rooted cuttings. Trigonelline and caffeine were positively correlated with H2O2 in all stages of development of adventitious roots. The correlations of trigoneline and caffeine with phenols and antioxidant enzymes reveal different profiles, depending on the phases. The results indicate that IBA and melatonin increase trigonelline and caffeine during the induction and initiation of adventitious roots in Coffea arabica cuttings, which is correlated with a higher percentage of rooted cuttings.

Species-specific transcriptional reprogramming during adventitious root initiation.

Adventitious roots or shoot-borne roots transdifferentiate from cells close to vascular tissues after cell reprogramming, which is associated with increased transcriptional activity. Recently, Garg et al. provided a genome-wide landscape of transcriptional signatures during the early stages of adventitious root initiation in rice and showed that conserved transcription factors acquire species-specific function.

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.

A simple, rapid, and quantifiable system for studying adventitious root formation in grapevine

Woody cutting is customarily utilized as a material in research on grape adventitious root formation (ARF). However, phenotypic heterogeneity caused by the complex background influenced its use for molecular mechanism research of ARF of grape. The present study tested various types of explants from grape tissue culture plantlets and found that the whole leaf: blade with the petiole (LP) was the simplest unit that can easily form adventitious roots (ARs). LP explants which can be easily obtained, directly generate ARs via de novo organogenesis from the base of the petiole. Plantlet age, node position, blade size, the health condition of leaves, and light intensity have been demonstrated to affect the homogeneity of the ARF phenotype in LP. By controlling these parameters, selected LPs cultured on a medium with 6 g·L-1 agar and 10 g·L-1 sucrose under dark conditions started rooting at 6–7 days after culture (DAC) and reached 100% rooting rate within 13–14 DAC. Using this system, the core role of auxin on ARF was verified by exogenous application of indole butyric acid (IBA) and N-1-naphthylphthalamic acid (NPA). Strikingly, we found that light promoted ARF in the absence of sucrose, but inhibited ARF in the presence of sucrose (10 g·L-1), while a low concentration of 0.34 µM NPA partially relieved the inhibition. Finally, this study confirmed that exogenous plant growth regulators (PGRs), including 6-benzyl aminopurine (6-BA), gibberellic acid 3 (GA3), and 2,4-epibrassinolide (EBR), significantly inhibited ARF. This simple, rapid, quantifiable ARF research system provides a new approach to studying the factors influencing the formation and development of grape adventitious roots and establishes a framework for investigating the mechanism of grape adventitious root induction and initiation.

Jasmonate inhibits adventitious root initiation through repression of CKX1 and activation of RAP2.6L transcription factor in Arabidopsis.

Adventitious rooting is a de novo organogenesis process that enables plants to propagate clonally and cope with environmental stresses. Adventitious root initiation (ARI) is controlled by interconnected transcriptional and hormonal networks, but there is little knowledge of the genetic and molecular programs orchestrating these networks. Thus, we have applied genome-wide transcriptome profiling to elucidate the transcriptional reprogramming events preceding ARI. These reprogramming events are associated with the down-regulation of cytokinin (CK) signaling and response genes, which could be triggers for ARI. Interestingly, we found that CK free base (iP, tZ, cZ, and DHZ) content declined during ARI, due to down-regulation of de novo CK biosynthesis and up-regulation of CK inactivation pathways. We also found that MYC2-dependent jasmonate (JA) signaling inhibits ARI by down-regulating the expression of the CYTOKININ OXIDASE/DEHYDROGENASE1 (CKX1) gene. We also demonstrated that JA and CK synergistically activate expression of the transcription factor RELATED to APETALA2.6 LIKE (RAP2.6L), and constitutive expression of this transcription factor strongly inhibits ARI. Collectively, our findings reveal that previously unknown genetic interactions between JA and CK play key roles in ARI.

The Effect of Different Levels of Indole-3-butyric Acid (IBA) and Naphthaleneacetic acid (NAA) on the Rooting of The Effect of Different Levels of Indole-3-butyric Acid (IBA) and Naphthaleneacetic acid (NAA) on the Rooting of Pear Stem CuPear Stem Cutting

The Effect of Different Levels of Indole-3-butyric Acid (IBA) and Naphthaleneacetic acid (NAA) on the Rooting of The Effect of Different Levels of Indole-3-butyric Acid (IBA) and Naphthaleneacetic acid (NAA) on the Rooting of Pear Stem CuPear Stem Cutting

AUREA maintains the balance between chlorophyll synthesis and adventitious root formation in tomato

Flooding tolerance is an important trait for tomato breeding. In this study, we obtained a recessive mutant exhibiting highly enhanced submergence resistance. Phenotypical analyses showed that this resistant to flooding (rf) mutant displays slightly chlorotic leaves and spontaneous initiation of adventitious roots (ARs) on stems. The mutation was mapped to the phytochromobilin synthase gene AUREA (AU), in which a single amino acid substitution from asparagine to tyrosine occurred. In addition to the classic function of AU in phytochrome and chlorophyll biogenesis in leaves, we uncovered its novel role in mediating AR formation on stems. We further observed temporal coincidence of the two phenotypes in the rf mutant: chlorosis and spontaneous AR formation and revealed that AU functions by maintaining heme homeostasis. Interestingly, our grafting results suggest that heme might play roles in AR initiation via long-distance transport from leaves to stems. Our results present genetic evidence for the involvement of the AU–heme oxygenase-1–heme pathway in AR initiation in tomato. As fruit production and yield in the rf mutant are minimally impacted, the mutation identified in this study may provide a target for biotechnological renovation of tomato germplasm in future breeding.

Red Light Controls Adventitious Root Regeneration by Modulating Hormone Homeostasis in Picea abies Seedlings.

Vegetative propagation relies on the capacity of plants to regenerate de novo adventitious roots (ARs), a quantitative trait controlled by the interaction of endogenous factors, such as hormones and environmental cues among which light plays a central role. However, the physiological and molecular components mediating light cues during AR initiation (ARI) remain largely elusive. Here, we explored the role of red light (RL) on ARI in de-rooted Norway spruce seedlings. We combined investigation of hormone metabolism and gene expression analysis to identify potential signaling pathways. We also performed extensive anatomical characterization to investigate ARI at the cellular level. We showed that in contrast to white light, red light promoted ARI likely by reducing jasmonate (JA) and JA-isoleucine biosynthesis and repressing the accumulation of isopentyl-adenine-type cytokinins. We demonstrated that exogenously applied JA and/or CK inhibit ARI in a dose-dependent manner and found that they possibly act in the same pathway. The negative effect of JA on ARI was confirmed at the histological level. We showed that JA represses the early events of ARI. In conclusion, RL promotes ARI by repressing the accumulation of the wound-induced phytohormones JA and CK.

Factors involved in the success of Castanea henryi stem cuttings in different cutting mediums and cutting selection periods

Chinquapin (Castanea henryi) is a dual-purpose tree species in China valued for as a source of timber and starch. We investigated the effect of four cutting mediums (pure vermiculite; peat:river sand at 3:1 v/v; peat:krasnozem at 1:1 v/v; and pure krasnozem) and three stem cutting periods (March, May, and July) on rooting performance of C. henryi cuttings. Different cutting periods and cutting mediums greatly influenced the rooting rate of C. henryi, ranging from 3.35 to 77.31%. Principal component analysis indicated that the best combination of cutting period and cutting medium was semi-hardwood cuttings (May cuttings) + krasnozem. Histological evidence indicated that adventitious root initials were present by week 5–6, and that the site of root primordia initiation was observed in the vascular cambium. Stem anatomical structures observed at different periods indicated that a xylem/radius ratio of 29.90–37.42% and a fractured phloem fiber ring are indicative of rooting success. The relational model between rooting index and medium properties indicated that nutrient content and porosity significantly influenced callus production. However, pH strongly affected C. henryi root formation, with the Pearson correlation coefficients for May and July cuttings of − 0.856 and − 0.947, respectively. Our protocol is helpful to achieve mass clone propagation of improved C. henryi genotypes, thus overcoming a common hurdle in chinquapin breeding programs.

Auxin regulation and MdPIN expression during adventitious root initiation in apple cuttings

Adventitious root (AR) formation is critical for the efficient propagation of elite horticultural and forestry crops. Despite decades of research, the cellular processes and molecular mechanisms underlying AR induction in woody plants remain obscure. We examined the details of AR formation in apple (Malus domestica) M.9 rootstock, the most widely used dwarf rootstock for intensive production, and investigated the role of polar auxin transport in postembryonic organogenesis. AR formation begins with a series of founder cell divisions and elongation of the interfascicular cambium adjacent to vascular tissues. This process is associated with a relatively high indole acetic acid (IAA) content and hydrolysis of starch grains. Exogenous auxin treatment promoted this cell division, as well as the proliferation and reorganization of the endoplasmic reticulum and Golgi membrane. In contrast, treatment with the auxin transport inhibitor N-1-naphthylphthalamic acid (NPA) inhibited cell division in the basal region of the cuttings and resulted in abnormal cell divisions during the early stage of AR formation. In addition, PIN-FORMED (PIN) transcripts were differentially expressed throughout the whole AR development process. We also detected upregulation of MdPIN8 and MdPIN10 during induction; upregulation of MdPIN4, MdPIN5, and MdPIN8 during extension; and upregulation of all MdPINs during AR initiation. This research provides an improved understanding of the cellular and molecular underpinnings of the AR process in woody plants.

The molecular mechanism underlying cadmium resistance in NHX1 transgenic Lemna turonifera was studied by comparative transcriptome analysis

Cadmium (Cd) is one of the most toxic heavy metals, which poses a serious threat to the environment. Our previous studies revealed that transgenic Lemna turonifera (hereafter mentioned as Transgenic) over expressing Na+/H+ Antiporter (AtNHX1) gene was more tolerant to Cd2+ stress than the Wild type plants (WT). To further explore the molecular mechanism underlying cadmium resistance, comprehensive transcriptome analysis and comparison were performed. For RNA-Seq, the trannsgenic and WT were treated with 50 μM CdCl2 for 24 h. In total, 2247 differentially expressed unigenes (DEGs) including 1195 upregulated and 1052 downregulated ones were discovered between Transgenic and WT samples. The downregulated genes associated with the adventitious root (AR), lateral root (LR) and root hair (RH) initiation might have prevented the root from abscission. Calcium signaling and ROS accumulation were regulated in response to cadmium stress. Moreover, the activation of genes involved in the production of trehalose and R-S glutathione increased the cadmium resistance of duckweed. Downregulation of genes involved in the transport of Cd2+ and upregulation of genes involved in vacuolar sequestration might have resulted in increased tolerance of Transgenic over WT. These findings might provide new ideas for improving plant cadmium resistance and phytoremediation. Comparative transcriptome analysis was applied to study the involvement of NHX1 in Cadmium detoxification. The genes associated with root, calcium signal and cadmium transports were regulated in transgenic duckweed.

ETHYLENE RESPONSE FACTOR 115 integrates jasmonate and cytokinin signaling machineries to repress adventitious rooting in Arabidopsis.

Adventitious root initiation (ARI) is a de novo organogenesis program and a key adaptive trait in plants. Several hormones regulate ARI but the underlying genetic architecture that integrates the hormonal crosstalk governing this process remains largely elusive. In this study, we use genetics, genome editing, transcriptomics, hormone profiling and cell biological approaches to demonstrate a crucial role played by the APETALA2/ETHYLENE RESPONSE FACTOR 115 transcription factor. We demonstrate that ERF115 functions as a repressor of ARI by activating the cytokinin (CK) signaling machinery. We also demonstrate that ERF115 is transcriptionally activated by jasmonate (JA), an oxylipin-derived phytohormone, which represses ARI in NINJA-dependent and independent manners. Our data indicate that NINJA-dependent JA signaling in pericycle cells blocks early events of ARI. Altogether, our results reveal a previously unreported molecular network involving cooperative crosstalk between JA and CK machineries that represses ARI.

An auxin-responsive transcription factor AbLBD1 promotes the development of lateral roots and reduces the biosynthesis of tropane alkaloids in Atropa belladonna

Atropa belladonna produces anticholinergic tropane alkaloids (TAs), such as hyoscyamine and scopolamine, which are synthesized in its lateral roots. Yet, the regulation of lateral root growth and TA biosynthesis remain poorly understood. In this study, an auxin-responsive transcription factor (AbLBD1), encoding a lateral organ boundaries domain protein (LBD), was functionally characterized from A. belladonna. Overexpression of AbLBD1 effectively promoted the initiation of lateral roots and adventitious roots of A. belladonna. The root biomass of AbLBD1-overexpressing lines was 1.48 to 2.45 fold higher that of the control. However, the contents of hyoscyamine and scopolamine were markedly reduced in AbLBD1-overexpressing lines. Gene expression analysis showed that the expression levels of TAs biosynthesis genes, namely AbPMT, AbPYKS, AbCYP82M3, and AbH6H, were greatly decreased in AbLBD1-overpressing lines. In conclusion, AbLBD1 plays a positive role in regulating lateral root development but a negative one in regulating TAs biosynthesis in A. belladonna. This study proved for the first time that AbLBD1 was a key auxin response regulator in root, which promotes initiation of lateral root and inhibits the biosynthesis of tropane alkaloids.

A miRNA-Encoded Small Peptide, vvi-miPEP171d1, Regulates Adventitious Root Formation.

One of the biggest challenges in clonal propagation of grapevine (Vitis vinifera) is difficulty of rooting. Adventitious root initiation and development are the critical steps in the cutting and layering process of grapevine, but the molecular mechanism of these processes remains unclear. Previous reports have found that microRNA (miRNA)-encoded peptides (miPEPs) can regulate plant root development by increasing the transcription of their corresponding primary miRNA. Here, we report the role of a miPEP in increasing adventitious root formation in grapevine. In this study, we performed a global analysis of miPEPs in grapevine and characterized the function of vvi-miPEP171d1, a functional, small peptide encoded by primary-miR171d. There were three small open reading frames in the 500-bp upstream sequence of pre-miR171d. One of them encoded a small peptide, vvi-miPEP171d1, which could increase the transcription of vvi-MIR171d Exogenous application of vvi-miPEP171d1 to grape tissue culture plantlets promoted adventitious root development by activating the expression of vvi-MIR171d Interestingly, neither exogenous application of the vvi-miPEP171d1 peptide nor overexpression of the vvi-miPEP171d1 coding sequence resulted in phenotypic changes in Arabidopsis (Arabidopsis thaliana). Similarly, application of synthetic ath-miPEP171c, the small peptide encoded by the Arabidopsis ortholog of vvi-MIR171d, inhibited the growth of primary roots and induced the early initiation of lateral and adventitious roots in Arabidopsis, while it had no effect on grape root development. Our findings reveal that miPEP171d1 regulates root development by promoting vvi-MIR171d expression in a species-specific manner, further enriching the theoretical research into miPEPs.

Changes in Tree Root Architecture Resulting from Field Nursery Production Practices1

AbstractNursery production practices subject tree root systems to mechanical and environmental factors that are not imposed on plants regenerated naturally from seed. Architecture of undisturbed root systems of nine trees species commonly planted in urban landscapes was compared to root architecture of these tree species produced using common field nursery production practices. When young nursery production seedlings are root-pruned prior to replanting, the loss of the lower portion of the main root and lateral roots emerging from it, and initiation of adventitious roots from the cut end, alter the root system architecture. Nursery production plants have 7 to 48 percent fewer natural lateral roots that could develop into flare roots than undisturbed plants. New roots initiated from the cut end of the main root on nursery production plants can substitute for the loss of lateral roots, if accepted practices are followed. Root architecture of trees is established early. With minor exceptions attributed to the loss of small roots less than 1 mm diameter, there were no significant changes in the number of lateral roots over the 4 year period in both nursery production and undisturbed plants. This consistent number of roots also suggests that pruning the main root did not stimulate additional lateral roots above the pruning cut. Root architecture of liner stock produced in nurseries can be equivalent to undisturbed root systems.Index words: Structural roots, root pruning, bare root, root depth, taproot, root flare.Species used in this study: Norway maple (Acer platanoides L.); green ash (Fraxinus pennsylvanica Marsh.); littleleaf linden (Tilia cordata L.); red maple (Acer rubrum L.); European white birch (Betula pendula Roth.); Kentucky coffee tree (Gymnocladus dioicus L.); domestic apple (Malus spp.); red oak (Quercus rubra L.); Siberian elm (Ulmus pumila Jacq.).

A Molecular Framework for the Control of Adventitious Rooting by TIR1/AFB2-Aux/IAA-Dependent Auxin Signaling in Arabidopsis

In Arabidopsis thaliana, canonical auxin-dependent gene regulation is mediated by 23 transcription factors from the AUXIN RESPONSE FACTOR (ARF) family that interact with auxin/indole acetic acid repressors (Aux/IAAs), which themselves form co-receptor complexes with one of six TRANSPORT INHIBITOR1/AUXIN-SIGNALLING F-BOX (TIR1/AFB) proteins. Different combinations of co-receptors drive specific sensing outputs, allowing auxin to control a myriad of processes. ARF6 and ARF8 are positive regulators of adventitious root initiation upstream of jasmonate, but the exact auxin co-receptor complexes controlling the transcriptional activity of these proteins has remained unknown. Here, using loss-of-function mutants we show that three Aux/IAA genes, IAA6, IAA9, and IAA17, act additively in the control of adventitious root (AR) initiation. These three IAA proteins interact with ARF6 and/or ARF8 and likely repress their activity in AR development. We show that TIR1 and AFB2 are positive regulators of AR formation and TIR1 plays a dual role in the control of jasmonic acid (JA) biosynthesis and conjugation, as several JA biosynthesis genes are up-regulated in the tir1-1 mutant. These results lead us to propose that in the presence of auxin, TIR1 and AFB2 form specific sensing complexes with IAA6, IAA9, and/or IAA17 to modulate JA homeostasis and control AR initiation.

A DAO1-Mediated Circuit Controls Auxin and Jasmonate Crosstalk Robustness during Adventitious Root Initiation in Arabidopsis.

Adventitious rooting is a post-embryonic developmental program governed by a multitude of endogenous and environmental cues. Auxin, along with other phytohormones, integrates and translates these cues into precise molecular signatures to provide a coherent developmental output. Auxin signaling guides every step of adventitious root (AR) development from the early event of cell reprogramming and identity transitions until emergence. We have previously shown that auxin signaling controls the early events of AR initiation (ARI) by modulating the homeostasis of the negative regulator jasmonate (JA). Although considerable knowledge has been acquired about the role of auxin and JA in ARI, the genetic components acting downstream of JA signaling and the mechanistic basis controlling the interaction between these two hormones are not well understood. Here we provide evidence that COI1-dependent JA signaling controls the expression of DAO1 and its closely related paralog DAO2. In addition, we show that the dao1-1 loss of function mutant produces more ARs than the wild type, probably due to its deficiency in accumulating JA and its bioactive metabolite JA-Ile. Together, our data indicate that DAO1 controls a sensitive feedback circuit that stabilizes the auxin and JA crosstalk during ARI.

What Makes Adventitious Roots?

The spermatophyte root system is composed of a primary root that develops from an embryonically formed root meristem, and of different post-embryonic root types: lateral and adventitious roots. Adventitious roots, arising from the stem of the plants, are the main component of the mature root system of many plants. Their development can also be induced in response to adverse environmental conditions or stresses. Here, in this review, we report on the morphological and functional diversity of adventitious roots and their origin. The hormonal and molecular regulation of the constitutive and inducible adventitious root initiation and development is discussed. Recent data confirmed the crucial role of the auxin/cytokinin balance in adventitious rooting. Nevertheless, other hormones must be considered. At the genetic level, adventitious root formation integrates the transduction of external signals, as well as a core auxin-regulated developmental pathway that is shared with lateral root formation. The knowledge acquired from adventitious root development opens new perspectives to improve micropropagation by cutting in recalcitrant species, root system architecture of crops such as cereals, and to understand how plants adapted during evolution to the terrestrial environment by producing different post-embryonic root types.

Exo-ethylene application mitigates waterlogging stress in soybean (Glycine max L.)

BackgroundWaterlogging (WL) is a key factor hindering soybean crop productivity worldwide. Plants utilize various hormones to avoid various stress conditions, including WL stress; however, the physiological mechanisms are still not fully understood.ResultsTo identify physiological mechanisms during WL stress, different phytohormones, such as ethephon (ETP; donor source of ethylene), abscisic acid, gibberellins, indole-3-acetic acid, kinetin, jasmonic acid, and salicylic acid were exogenously applied to soybean plants. Through this experiment, we confirmed the beneficial effects of ETP treatment. Thus, we selected ETP as a candidate hormone to mitigate WL. Further mechanistic investigation of the role of ETP in waterlogging tolerance was carried out. Results showed that ETP application mitigated WL stress, significantly improved the photosynthesis pigment, and increased the contents of endogenous GAs compared to those in untreated plants. The amino acid contents during WL stress were significantly activated by EPT treatments. The amino acid contents were significantly higher in the 100 μM ETP-treated soybean plants than in the control. ETP application induced adventitious root initiation, increased root surface area, and significantly increased the expressions of glutathione transferases and relative glutathione activity compared to those of non-ETP-treated plants. ETP-treated soybeans produced a higher up-regulation of protein content and glutathione S-transferase (GSTs) than did soybeans under the WL only treatment.ConclusionsIn conclusion, the current results suggest that ETP application enabled various biochemical and transcriptional modulations. In particular, ETP application could stimulate the higher expression of GST3 and GST8. Thus, increased GST3 and GST8 induced 1) increased GSH activity, 2) decreased reactive oxygen species (ROS), 3) mitigation of cell damage in photosynthetic apparatus, and 4) improved phenotype consecutively.