Carbon Monoxide Modulates Auxin Transport and Nitric Oxide Signaling in Plants under Iron Deficiency Stress

Carbon monoxide(CO)and nitric oxide(NO)are signal molecules that enhance plant adaptation to environmental stimuli.Auxin is an essential phytohormone for plant growth and development.CO and NO play crucial roles in modulating the plant’s response to iron deficiency.Iron deficiency leads to an increase in the activity of heme oxygenase(HO)and the subsequent generation of CO.Additionally,it alters the polar subcellular distribution of Pin-Formed 1(PIN1)proteins,resulting in enhanced auxin transport.This alteration,in turn,leads to an increase in NO accumulation.Furthermore,iron deficiency enhances the activity of ferric chelate reductase(FCR),as well as the expression of the Fer-like iron deficiency-induced transcription factor 1(FIT)and the ferric reduction oxidase 2(FRO2)genes in plant roots.Overexpression of the long hypocotyl 1(HY1)gene,which encodes heme oxygenase,or the CO donor treatment resulted in enhanced basipetal auxin transport,higher FCR activity,and the expression of FIT and FRO2 genes under Fe deficiency.Here,a potential mechanism is proposed:CO and NO interact with auxin to address iron deficiency stress.CO alters auxin transport,enhancing its accumulation in roots and up-regulating key iron-related genes like FRO2 and IRT1.Elevated auxin levels affect NO signaling,leading to greater sensitivity in root development.This interplay promotes FCR activity,which is crucial for iron absorption.Together,these molecules enhance iron uptake and root growth,revealing a novel aspect of plant physiology in adapting to environmental stress.

Role of PLC-PIP2 and cAMP-PKA Signal Pathways in Radiation-induced Immune-suppressing Effect

Objective The purpose of the present study was to observe the changes in CD4＋CD25＋Nrpl＋Treg cells after irradiation with different doses and explore the possible molecular mechanisms involved. Methods ICR mice and mouse lymphoma cell line （EL-4 cells） was used. The expressions of CD4, CD25, Nrpl, calcineurin and PKC-α were detected by flow cytometry. The expressions of TGF-131, IL-10, PKA and cAMP were estimated with ELISA. Results At 12 h after irradiation, the expression of Nrpl increased significantly in 4.0 Gy group, compared with sham-irradiation group （P〈0.05） in the spleen and thymus, respectively, when ICR mice received whole-body irradiation （WBI）. Meanwhile the synthesis of Interleukin 10 （IL-20） and transforming growth factor-β1 （TGF-β1） increased significantly after high dose irradiation （HDR） （〉 or = 1.0 Gy）. In addition, the expression of cAMP and PKA protein increased, while PKC-α, calcineurin decreased at 12h in thymus cells after 4.0 Gy X-irradiation. While TGF-β1 was clearly inhibited when the PLC-PIP2 signal pathway was stimulated or the cAMP-PKA signal pathway was blocked after 4.0 Gy X-irradiation, this did not limit the up-regulation of CD4＋CD25＋Nrpl＋Treg cells after ionizing radiation. Conclusion These results indicated that HDR might induce CD4＋CD25＋Nrpl＋Treg cells production and stimulate TGF-β1 secretion by regulating signal molecules in mice.

Lactate metabolism in neurodegenerative diseases

Lactate,a byproduct of glycolysis,was thought to be a metabolic waste until the discovery of the Warburg effect.Lactate not only functions as a metabolic substrate to provide energy but can also function as a signaling molecule to modulate cellular functions under pathophysiological conditions.The Astrocyte-Neuron Lactate Shuttle has cla rified that lactate plays a pivotal role in the central nervous system.Moreover,protein lactylation highlights the novel role of lactate in regulating transcription,cellular functions,and disease development.This review summarizes the recent advances in lactate metabolism and its role in neurodegenerative diseases,thus providing optimal pers pectives for future research.

Seed Priming and Foliar Supplementation withβ-aminobutyric Acid Alleviates Drought Stress through Mitigation of Oxidative Stress and Enhancement of Antioxidant Defense in Linseed(Linum usitatissimum L.)

Drought is one of the critical limitations to agricultural soils and crop plants.Scarcity of water is increasing due to climate change that lead to increasing threats to global food security.Therefore,ecofriendly and cost effective strategies are highly desirable for mitigating drought stress along with sustainable and smart agricultural production.The aim of the study was to mitigate DS using seed priming and exogenous supplementation ofβ-aminobutyric acid(BABA)in linseed(Linum usitatissimum L.).Different doses(0,50,100 and 150μM)of BABA were used for seed priming agent and foliar spraying under three soil moisture levels viz.,25%(SM25),45%(SM45)and 65%(SM65).The response variables of both experiments included different agro-botanical traits and oxidative stress indicators such as melondialdehyde content,free proline accumulation,and antioxidant defense in plants.The linseed plants showed water stress at SM25 that reduced plant height,number of branches per plant,time taken to flower initiation and heading,and root and shoot dry weights.Additionally,the number of capsules and seeds per capsule showed a significant decline at SM25,which led to a drastic reduction in 100-seed weight yield in linseed plants in both experiments.However,seed priming and foliar supplementation with of BABA(50–100μM)significantly improved these morpho-agronomical attributes in linseed plants under DS.The results revealed that the BABA was fully active in linseed plants at SM25.Interestingly,the combination of SM25 with BABA significantly improved the antioxidant enzymes superoxide dismutase(SOD),catalase(CAT),ascorbate peroxidase(APX),and peroxidase(POD)activity,which significantly enhanced DS tolerance in linseed plants.These findings might be useful to oil seed breeders and farmers linseed for breeding program in linseed plants as well as sustainable agricultural production of oil seed crop plants.

TIR enzymatic functions:signaling molecules and receptor mechanisms

The evolutionarily conserved Toll/Interleukin-1 Receptor(TIR)domains across kingdoms of prokaryotes,plants,and animals play critical roles in innate immunity.Recent studies have revealed the enzymatic functions of TIRs,the structural bases of TIRs as holoenzymes,and the identity of TIR-generated small signaling molecules and their receptors,which significantly advanced our understanding on TIR-mediated immune signaling pathways.We reviewed the most up-to-date findings in TIR enzymatic functions from the perspectives of signaling molecules and receptor mechanisms.

Encouraging specific biomarkers-based therapeutic strategies for hepatocellular carcinoma

The prevention,early discovery and effective treatment of patients with hepatocellular carcinoma(HCC)remain a global medical challenge.At present,HCC is still mainly treated by surgery,supplemented by vascular embolization,radio frequency,radiotherapy,chemotherapy and biotherapy.The application of multikinase inhibitor sorafenib,chimeric antigen receptor T cells,or PD-1/PD-L1 inhibitors can prolong the median survival of HCC patients.However,the treatment efficacy is still unsatisfactory due to HCC metastasis and postoperative recurrence.During the process of hepatocyte malignant transformation,HCC tissues can express and secrete many types of specific biomarkers,or oncogenic antigen molecules into blood,for example,alpha-fetoprotein,glypican-3,Wnt3a(one of the key signaling molecules in the Wnt/β-catenin pathway),insulin-like growth factor(IGF)-II or IGF-I receptor,vascular endothelial growth factor,secretory clusterin and so on.In addition,combining immunotherapy with noncoding RNAs might improve anti-cancer efficacy.These biomarkers not only contribute to HCC diagnosis or prognosis,but may also become molecular targets for HCC therapy under developing or clinical trials.This article reviews the progress in emerging biomarkers in basic research or clinical trials for HCC immunotherapy.

Possible mechanism of 15D-PGJ2 in promoting periodontal tissue regeneration in patients with mandibular defects

Objective:To explore the main physiological mechanism of 15d-PGJ2 promoting periodontal tissue regeneration in patients with jaw defects caused by periodontal disease.Methods:From February 2016 to July 2019,a controlled study was conducted on 73 healthy residents(healthy group)and 73 patients(case group)with periodontal disease combined with jaw defects in Changsha medical university.T test was used to compare the growth factors of gingival crevicular fluid between the two groups.Peripheral blood cells;Cement-specific protein;Peripheral blood enzyme;Statistical differences in bone metabolites.The t test method compared the content of each index before and after treatment(15d-PGJ2 was treated at a dose of 200 mu/kg for 14 days).The method of factor analysis explores the internal correlation of each index.Result:RANKL,ICAM-1,TGF-β1,Th17,Treg,PDLSCs,SOST,CAP,HMGB1,CTSK,5-LOX,COX-2,NTX were higher in the case group than in the healthy group.In the case group,RANKL,ICAM-1,TGF-β1,Th17,Treg,PDLSCs,SOST,CAP,HMGB1,CTSK,5-LOX,COX-2,NTX were lower than those in the healthy group.The differences between the groups were statistically significant(P<0.05).Compared with before treatment,IL-1β,IL-17,Bfgf,YKL-40,BMP-2,ICTP,PICP,CTX were significantly decreased after treatment.RANKL,ICAM-1,TGF-β1,Th17,Treg,PDLSCs,SOST,CAP,HMGB1,CTSK,5-LOX,COX-2,NTX were significantly increased.The differences were statistically significant(P<0.05).Factor analysis shows that four common factors can be extracted from 21 indicators,and the cumulative contribution rate is 96.993%.Conclusions:The treatment of 15d-PGJ2 in patients with periodontal disease with maxillary defects can significantly affect the expression of multiple characteristic indicators,which may involve four mechanisms:dysregulation of cell differentiation or migration,local inflammation or immune imbalance,destruction of alveolar bone microstructure,load or stimulation,and remodeling.The specific pathway related to this is still to be further explored.

Effects of abiotic stress and hormones on the expressions of five13-CmLOXs and enzyme activity in oriental melon(Cucumis melo var.makuwa Makino)

Lipoxygenases（LOXs） are a group of non-heme,iron-containing enzymes and extensively involved in plant growth and development,ripening and senescence,stress responses,biosynthesis of regulatory molecules and defense reaction.In our previous study,18 LOXs in melon genome were screened and identified,and five 13-LOX genes（CmLOX08,CmLOX10,CmLOX12,CmLOX13 and CmLOX18） were predicted to locate in chloroplast.Phylogenetic analysis result showed that the five genes have high homology with jasmonic acid（JA） biosynthesis-related LOXs from other plants.In addition,promoter analysis revealed that motifs of the five genes participate in gene expression regulated by hormones and stresses.Therefore,we analyzed the expressions of the five genes and LOX activity in leaves of four-leaf stage seedlings of oriental melon cultivar Yumeiren under abiotic stress：wounding,cold,high temperature and hydrogen peroxide（H_2O_2）,and signal molecule treatments：methyl jasmonate（MeJA）,abscisic acid（ABA） and salicylic acid（SA）.Real time qPCR revealed that wounding and H_2O_2 induced the expressions of all the five genes.Only CmLOX08 was induced by cold while only CmLOX13 was suppressed by high temperature.ABA induced the expressions of CmLOXIO and CmLOX12 while inhibited CmLOX13 and CmLOX18.MeJA increased the 3 genes expressions except CmLOX08 and CmLOX13,whereas SA decreased the effect,apart from CmLOX12.All the abiotic stresses and signal molecules treatments increased the LOX activity in leaves of oriental melon.In summary,the results suggest that the five genes have diverse functions in abiotic stress and hormone responses,and might participate in defense response.The data generated in this study will be helpful in subcellular localization and transgenic experiment to understand their precise roles in plant defense response.

Roles of dietary supplementation with arginine or N-carbamylglutamate in modulating the inflammation, antioxidant property, and m RNA expression of antioxidant-relative signaling molecules in the spleen of rats under oxidative stress

This study evaluated the effects of arginine(Arg) or N-carbamylglutamate(NCG) on inflammation, antioxidant property, and antioxidant-related gene expression in rat spleen under oxidative stress. A total of 52 rats were randomly distributed into 4 treatment groups with 13 replicates per group. Rats were fed a basal diet(BD) or BD supplemented with Arg or NCG for 30 days. On day 28, half of the BD-fed rats were intraperitoneally injected with sterile saline(control group), and the other half with 12 mg/kg body weight of diquat(DT; DT group). The other 2 diet groups were intraperitoneally injected with 12 mg/kg body weight of DT with either Arg(1%)(DT t Arg) or NCG(0.1%)(DT t NCG). Rat spleen samples were collected for analysis at 48 h after DT injection. Results showed that DT damaged the antioxidant defense in rats compared with the control group(P < 0.05). Compared with the DT group, the DT t Arg and DT t NCG groups manifested improved anti-hydroxyl radical, catalase, and total superoxide dismutase(T-SOD) activities, increased glutathione content(P < 0.05), and decreased malondialdehyde content(P < 0.05).Moreover, compared with the DT group, the DT t Arg and DT t NCG groups enhanced mRNA expression of superoxide dismutase(SOD), glutathione peroxidase 1(GPx1), glutathione reductase(GR), nuclear factor erythroid 2-related factor 2(Nrf2), Kelch-like ECH-associated protein 1(Keap-1), and mammalian target of rapamycin(m TOR)(P < 0.05). Both NCG and Arg significantly increased anti-inflammatory cytokine mRNA level but suppressed the pro-inflammatory cytokine mRNA expression under oxidative stress(P < 0.05). In summary, NCG and Arg effectively alleviated oxidative stress, improved the antioxidant capacity and regulated the antioxidant-related signaling molecular expression in rat spleen. N-carbamylglutamate and Arg reduced the inflammation in the spleen by mediating the gene expression of anti-inflammatory and pro-inflammatory cytokines and transforming growth factor-β(TGF-β).

Insights into constructing a stable and efficient microbial consortium

Microbial consortia are ubiquitous in nature,in which multiple microbial species cooperate to complete some important tasks such as lignocellulose degradation.Because of the advantages such as reduced metabolic burden and robustness to environment disturbances,developing a microbial consortium is a promising approach for valuable product synthesis,lignocellulose utilization,human health care,bioremediation and sustainable energy,etc.Despite the benefits,however,most artificial microbial consortia confront the problems of instability and low efficiency due to growth competition and metabolite incompatibility.To overcome these challenges,multiple strategies to design efficient synthetic microbial consortia have been reported.In this review,the interactions that determine the stability and performance of microbial consortia were described.Progress of artificial microbial consortia research was summarized,and the key strategies i.e.,spatial or temporal segregation,separated utilization of nutrients,nutrient cross-feeding and division of labor,that will be of great importance for achieving a stable and efficient microbial consortium were highlighted.Two novel advanced tools,signaling molecule systems and computational models,were also introduced and discussed.We believed that combining the universal cell–cell signaling molecule systems with computational models will be promising for synthetic microbial consortia construction in the future.

Recent advances in nano-enabled agriculture for improving plant performance

Nano-enabled agriculture is an emerging hot topic.To facilitate the development of nano-enabled agriculture,reviews addressing or discussing the applications,knowledge gap,future research needs,and possible new research field of plant nanobiotechnology in agricultural production are encouraged.Here we review the following topics in plant nanobiotechnology for agriculture:1)improving stress tolerance,2)stress sensing and early detection,3)targeted delivery and controlled release of agrochemicals,4)transgenic events in non-model crop species,and 5)seed nanopriming.We discuss the knowledge gaps in these topics.Besides the use of nanomaterials for harvesting more electrons to improve photosynthetic performance,they could be used to convert n IR and UV to visible light to expand the light spectrum for photosynthesis.We discuss this approach to maintaining plant photosynthesis under light-insufficient conditions.Our aim in this review is to aid researchers to learn quickly how to use plant nanobiotechnology for improving agricultural production.

Quantitative Structure-property Relationship Studies on Amino Acid Conjugates of Jasmonic Acid as Defense Signaling Molecules

Jasmonates and related compounds, including amino acid conjugates of jasmonic acid, have regulatory functions in the signaling pathway for plant developmental processes and responses to the complex equilibrium of biotic and abiotic stress. But the molecular details of the signaling mechanism are still poorly understood. Statistically significant quantitative structure-property relationship models （r^2 〉 0.990） constructed by genetic function approximation and molecular field analysis were generated for the purpose of deriving structural requirements for lipophilicity of amino acid conjugates of jasmonic acid. The best models derived in the present study provide some valuable academic information in terms of the 2/3D-descriptors influencing the lipophilicity, which may contribute to further understanding the mechanism of exogenous application ofjasmonates in their signaling pathway and designing novel analogs of jasmonic acid as ecological pesticides.

Interplay between hydrogen sulfide and other signaling molecules in the regulation of guard cell signaling and abiotic/biotic stress response

Stomatal aperture controls the balance between transpirational water loss and photosynthetic carbon dioxide(CO2)uptake.Stomata are surrounded by pairs of guard cells that sense and transduce environmental or stress signals to induce diverse endogenous responses for adaptation to environmental changes.In a recent decade,hydrogen sulfide(H2S)has been recognized as a signaling molecule that regulates stomatal movement.In this review,we summarize recent progress in research on the regulatory role of H2S in stomatal movement,including the dynamic regulation of phytohormones,ion homeostasis,and cell structural components.We focus especially on the cross talk among H2S,nitric oxide(NO),and hydrogen peroxide(H2O2)in guard cells,as well as on H2S-mediated post-translational protein modification(cysteine thiol persulfidation).Finally,we summarize the mechanisms by which H2S interacts with other signaling molecules in plants under abiotic or biotic stress.Based on evidence and clues from existing research,we propose some issues that need to be addressed in the future.

Axon regeneration impediment: the role of paired immunoglobulin-like receptor B

Regenerative capacity is weak after central nervous system injury because of the absence of an enhancing microenvironment and presence of an inhibitory microenvironment for neuronal and axonal repair. In addition to the Nogo receptor（Ng R）, the paired immunoglobulin-like receptor B（Pir B） is a recently discovered coreceptor of Nogo, myelin-associated glycoprotein, and myelin oligodendrocyte glycoprotein. Concurrent blocking of Ng R and Pir B almost completely eliminates the inhibitory effect of myelin-associated inhibitory molecules on axonal regeneration. Pir B participates in a key pathological process of the nervous system, specifically axonal regeneration inhibition. Pir B is an inhibitory receptor similar to Ng R, but their effects are not identical. This study summarizes the structure, distribution, relationship with common nervous system diseases, and known mechanisms of Pir B, and concludes that Pir B is also distributed in cells of the immune and hematopoietic systems. Further investigations are needed to determine if immunomodulation and blood cell migration involve inhibition of axonal regeneration.

Quantitative modeling of bacterial quorum sensing dynamics in time and space

Quorum sensing (QS) refers to the cell communication through signaling molecules that regulate many important biological functions of bacteria by monitoring their population density. Although a wide spectrum of studies on the QS system mechanisms have been carried out in experiments, mathematical modeling to explore the QS system has become a powerful approach as well. In this paper, we review the research progress of network modeling in bacterial QS to capture the system's underlying mechanisms. There are four types of QS system models for bacteria: the Gram-negative QS system model, the Gram-positive QS system model, the model for both Gram-negative and Gram-positive QS system, and the synthetic QS system model. These QS system models are mostly described by the ordinary differential equations (ODE) or partial differential equations (PDE) to study the changes of signaling molecule dynamics in time and space and the cell population density variations. Besides the deterministic simulations, the stochastic modeling approaches have also been introduced to discuss the noise effects on kinetics in QS systems. Taken together, these current modeling efforts advance our understanding of the QS system by providing systematic and quantitative dynamics description, which can hardly be obtained in experiments.

EDS1 modules as two‑tiered receptor complexes for TIR‑catalyzed signaling molecules to activate plant immunity

Plant intracellular nucleotide-binding leucine-rich repeat(NLR)receptors with an N-terminal Toll/Interleukin-1 recep-tor(TIR)domain detect pathogen effectors to produce TIR-catalyzed signaling molecules for activation of plant immunity.Plant immune signaling by TIR-containing NLR(TNL)proteins converges on Enhanced Disease Suscepti-bility 1(EDS1)and its direct partners Phytoalexin Deficient 4(PAD4)or Senescence-Associated Gene 101(SAG101).TNL signaling also require helper NLRs N requirement gene 1(NRG1)and activated disease resistance 1(ADR1).In two recent remarkable papers published in Science,the authors show that the TIR-containing proteins catalyze and produce two types of signaling molecules,ADPr-ATP/diADPR and pRib-AMP/ADP.Importantly,they demonstrate that EDS1-SAG101 and EDS1-PAD4 modules are the receptor complexes for ADPr-ATP/diADPRp and Rib-AMP/ADP,respec-tively,which allosterically promote EDS1-SAG101 interaction with NRG1 and EDS1-PAD4 interaction with ADR1.Thus,two different small molecules catalyzed by TIR-containing proteins selectively activate the downstream two distinct branches of EDS1-mediated immune signalings.These breakthrough studies significantly advance our understanding of TNL downstream signaling pathway.

The role of signal production and transduction in induced resistance of harvested fruits and vegetables

Postharvest diseases are the primary reason causing postharvest loss of fruits and vegetables.Although fungicides show an effective way to control postharvest diseases,the use of fungicides is gradually being restricted due to safety,en vironmental polluti on,and resista nee developme nt in the pathogens.Induced resista nee is a new strategy to control postharvest diseases by eliciti ng immune activity in fruits and vegetables with exogenous physical,chemical,and biological elicitors.After being stimulated by elicitors,fruits and vegetables respond immediately against pathoge ns.This process is actually a conti nuous signal tra nsducti on,in eluding the generati on,transduction,and interact!on of signal molecules.Each step of response can lead to corresponding physiological functi ons,and ultimately induce disease resista nee by upregulating the expressi on of disease resista nee genes and activati ng a variety of metabolic pathways.Signal molecules not only mediate defe nse resp onse alone,but also in teract with other signal tra nsducti on pathways to regulate the disease resista nee resp on se.Among various signal molecules,the sec ond messenger(reactive oxygen species,nitric oxide,calcium ions)and plant hormones(salicylic acid,jasmonic acid,ethylene,and abscisic acid)play an importa nt role in induced resista nee.This article summarizes and reviews the research progress of induced resista nee in recent years,and expounds the role of the above-me ntioned signal molecules in induced resista nee of harvested fruits and vegetables,and prospects for future research.

Hydrogen Peroxide in Plants:a Versatile Molecule of the Reactive Oxygen Species Network

Plants often face the challenge of severe environmental conditions, which include various biotic and abiotic stresses that exert adverse effects on plant growth and development. During evolution, plants have evolved complex regulatory mechanisms to adapt to various environmental stressors. One of the consequences of stress is an increase in the cellular concentration of reactive oxygen species （ROS）, which are subsequently converted to hydrogen peroxide （H2O2）. Even under normal conditions, higher plants produce ROS during metabolic processes. Excess concentrations of ROS result in oxidative damage to or the apoptotic death of cells. Development of an antioxidant defense system in plants protects them against oxidative stress damage. These ROS and, more particularly, H2O2, play versatile roles in normal plant physiological processes and in resistance to stresses. Recently, H2O2 has been regarded as a signaling molecule and regulator of the expression of some genes in cells. This review describes various aspects of H2O2 function, generation and scavenging, gene regulation and cross-links with other physiological molecules during plant growth, development and resistance responses.

Nature’s marvels endowed in gaseous molecules Ⅰ:Carbon monoxide and its physiological and therapeutic roles

Nature has endowed gaseous molecules such as O_(2),CO_(2),CO,NO,H2 S,and N2 with critical and diverse roles in sustaining life,from supplying energy needed to power life and building blocks for life ’s physical structure to mediating and coordinating cellular functions.In this article,we give a brief introduction of the complex functions of the various gaseous molecules in life and then focus on carbon monoxide as a specific example of an endogenously produced signaling molecule to highlight the importance of this class of molecules.The past twenty years have seen much progress in understanding CO’s mechanism(s) of action and pharmacological effects as well as in developing delivery methods for easy administration.One remarkable trait of CO is its pleiotropic effects that have few parallels,except perhaps its sister gaseous signaling molecules such as nitric oxide and hydrogen sulfide.This review will delve into the sophistication of CO-mediated signaling as well as its validated pharmacological functions and possible therapeutic applications.

Nitric Oxide and Brassinosteroids Mediated Fungal Endophyte-Induced Volatile Oil Production Through Protein Phosphorylation Pathways in Atractylodes lancea Plantlets

Fungal endophytes have been isolated from almost every plant, infecting their hosts without causing visible disease symptoms, and yet have still proved to be involved in plant secondary metabolites accumulation. To decipher the possible physiological mechanisms of the endophytic fungus-host interaction, the role of protein phosphorylation and the relationship between endophytic fungus-induced kinase activity and nitric oxide （NO） and brassinolide （BL） in endophyte-enhanced volatile oil accumulation in Atractylodes lancea plantlets were investigated using pharmacological and biochemical approaches. Inoculation with the endophytic fungus Gilmaniella sp. ALl2 enhanced the activities of total protein phosphorylation, Ca2^-dependent protein kinase, and volatile oil accumulation in A. lancea plantlets. The upregulation of protein kinase activity could be blocked by the BL inhibitor brassinazole. Furthermore, pretreatments with the NO-specific scavenger cPTIO significantly reduced the increased activities of protein kinases in A. lancea plantlets inoculated with endophytic fungus. Pretreatments with different protein kinase inhibitors also reduced fungus-induced NO production and volatile oil accumulation, but had barely no effect on the BL level. These data suggest that protein phosphorylation is required for endophyte- induced volatile oil production in A. lancea plantlets, and that crosstalk between protein phosphorylation and the NO pathway may occur and act as a downstream signaling event of the BL pathway.