Spatio-temporal dynamics of phytohormones in the tomato graft healing process

Graft healing involves a series of cytological and molecular events including wound responses, callus formation and vascular bundle remodelling. Hormones are important signalling molecules regulating plant development and responses to environmental stimuli. However,the detailed dynamics of phytohormones in graft healing remain elusive. In this research, internodes above and below the graft site were harvested from 0 to 168 h after grafting(HAG), and liquid chromatography tandem mass spectrometry(LC-MS/MS) was used to determinate jasmonic acid, auxin, cytokinin, ethylene, salicylic acid, abscisic acid and gibberellin levels during the graft healing process. Uniform manifold approximation and projection(UMAP) and k-means analyses were performed to explore hormone spatio-temporal dynamics. We found the stage-specific and asymmetric accumulation of phytohormones in the tomato graft healing process. At the early healing stage(before vascular bundle reconnection), IAA, cZ, ABA, JA and SA mainly accumulated above the graft site, while tZ and ACC mainly accumulated below the graft site. MEIAA, ICAld and IP mainly accumulated at the later stage. Comminated with the healing process, we suggested that JA is mainly involved in wound responses, IAA is beneficial to the formation of callus and vascular cell development, tZ promotes cell division, and IP is linked to vascular bundle remodelling. In addition, expression of JA-related genes SlMYC2 and SlJAZ2, IAA-related gene SlIAA1, tZ-related genes SlHP2 and SlRR8, and IP-related gene SlRR9 correlated with hormone accumulation. The findings provide important information about the hormones and genes involved in the tomato graft healing process.

The Role of Phytohormones in Alleviating Salt Stress in Rice

Rice is a crucial food crop globally.Soil salt stress has adverse effects on the physiology and biochemistry of rice,leading to ionic toxicity and disrupted metabolism.Research aimed at improving salt tolerance and understanding its underlying mechanisms in rice is becoming increasingly important.Phytohormones are crucial in managing rice’s reaction to salt stress by controlling its physiological and biochemical functions.Some phytohormones can improve salt tolerance in rice by affecting gene programming,protein expression,and salt stress signaling,thereby helping rice adapt to salt-stressed environments.This review highlights recent advancements in understanding how various phytohormones-such as abscisic acid(ABA),auxin(IAA),cytokinins(CKs),jasmonates(JA),gibberellins(GAs),melatonin(MT),salicylic acid(SA),ethylene(ETHY)and brassinosteroids(BRs)-help mitigate the detrimental effects of salt stress in rice.Additionally,we explore the current challenges and future research directions for utilizing exogenous phytohormone regulators to boost rice’s resistance to salt stress.

Nano-controlled release of phytohormones will broaden its application on plant protection

Phytohormone is a key regulator of plant growth and development.It has important effects on plant under biotic and abiotic stresses.However,the dose control of phytohormone is always a difficult problem in the application process,which limits the application range of phytohormone.Nanotechnology,because of its characteristics of controlled release,targeted therapy,non-pollution,high adsorption,lower volatilization of active substances,and low dosage of drug,comes into researchers’vision.Nanomaterials were directly applicated on crops at the early stage,and then active substances,such as pesticides,were encapsulated with nanomaterials,also achieved good results in the field.Currently,more and more attentions have been paid to nano-enabled delivery of phytohormones to plants,and formed a new field in agriculture.In present work,we reviewed the existing literatures,focused on the important regulatory roles of phytohormones in plant growth and development and their application potential,and the development and application prospect of nanomaterials combined with phytohormones were also have been discussed.

Effects of Various Phytohormones on Seed Germination and Seedling Growth of Leymus Chinensis

[Objective] To explore the effects of various phytohormones at different concentrations on the seed germination and seedling growth of Leymus Chinensiss （ L. chinensis）. [ Method ] The seeds of two varieties of L. chinensis were respectively treated with four kinds of phytohormone [ gibbereUin （ GA ）, 2,4-D, naphthalene acetic acid and 6-benzyl aminopurine （6-BA） ] for the observation of seed germination. The seedling growth of natural L. chinensis was observed after the seedlings were respectively treated with these phytohormones. [Result] The germination percentage of L. chinensis was promoted by the GAs and 6-BA at low concentration and inhibited by these two kinds of phytohormone at high concentration. Moreover, they promoted the seedling growth of L. chinensis, and the GA3 had better effect. However, the NAA and 2,4-D at any concentration inhibited the seed germination and seedling growth of L. chinensis. [ Conclusion] The various phytohormones have different effects on the seed germination and seedling growth of L. chinensis.

Characterization of the 19 Novel Cotton FLA Genes and Their Expression Profiling in Fiber Development and in Response to Phytohormones and Salt Stress

Fasciclin-like arabinogalactan proteins(FLAs),a subclass of arabinogalactan proteins(AGPs),are usually involved in cell development in plants.To investigate the expression profiling as well

Effect of Phytohormones on Adventitious Bud Differentiation from Bulb Scales of Oriental Lily Test-tube Plantlets

[Objective] The purpose of this study is to investigate the effects of differ- ent phytohormones on the adventitious bud differentiation of oriental lily. [Method] The bulb scales of the test-tube plantlets of Tiber, Rodina and Constanta were cul- tured in media supplemented with different cytokinin and auxin at different concen- tration, and then the adventitious buds in each treatment were calculated. [Result] Cytokinins had different influence on the adventitious bud differentiation of the three oriental lily cultivars. Among them, 6-BA had the best effect to induce the adventi- tious bud differentiation from bulb scales of Tiber and Rodina, but there was some difference in the optimal concentration. KT had the best effect to induce the adven- titious bud differentiation of Constanta. The auxins had little influence on the quality of the adventitious bud of the three oriental lily cultivars, but caused some difference in differentiation coefficients. [Conclusion] The most suitable media for the adventi- tious bud differentiation from bulb scales in vitro of Tiber, Rodina and Constanta were MS＋0.2 mg/L 6-BA＋0.2 mg/L 2,4-D, MS＋I.0 mg/L 6-BA＋0.2 mg/L IAA, MS＋ 1.0 mg/L KT＋0.5 mg/L 2,4-D, respectively.

Simultaneous determination of multi endogenous phytohormones in rice tissues by GC/MS

Although at different content levels, phytohormones including auxins, gibberellins, cytokinns and ahscisic acid distribute widely over rice tissues. It has

Abiotic Stresses and Phytohormones Regulate Expression of FAD2 Gene in Arabidopsis thaliana

Modification of unsaturated fatty acid （FA） levels has been found to accompany multiple abiotic stress acclimations in many plants. Delta 12 fatty acid desaturase （FAD2） plays a critical role in the synthesis of polyunsaturated FAs in plant cells by converting oleic acid （18：1） to linoleic acid （18：2）. To better understand the relationship between polyunsaturated FAs metabolism and stress adaptation, the expression of FAD2 gene and changes in the FA compositions under various abiotic stresses and phytohormone treatments in Arabidopsis thaliana was investigated in this study. A 1 423-bp promoter of the FAD2 gene was cloned and characterized from Arabidopsis. Several putative hormone- and stress- inducible cis-elements were identified in the cloned promoter, which include salt- and pathogen-inducible GT-1 motifs, low-temperature-responsive MYC element, dehydration-responsive MYB element, and GA signaling related WRKY71OS element. To investigate the fine regulation of FAD2 gene, a recombinant FAD2 promoter-GUS construct was introduced into Arabidopsis plants. Histochemical study showed that the promoter was ubiquitously active and responsive not only to exogenous phytohormones including ABA, 24-eBL, and SA but also to darkness, temperature, salt, and sucrose stresses in Arabidopsis seedlings. Consistent with the expression change, treatments with exogenous 24-eBL, ABA, SA, and NaCl resulted in reduction in polyunsaturated FAs in Arabidopsis seedlings. These findings suggest that the FAD2 gene with a wide variety of putative response elements in its promoter is responsive to multiple phytohormones and abiotic stresses and therefore may play an important role in stress responses of Arabidopsis during plant growth and seed development.

Regulation of phytohormones on root primordium initiation and adventitious root formation in the etiolated shoots of Paeonia suffruticosa'Yinfen Jinlin'

Tree peony is well known and sought after for its large, colorful flowers. Its propagation is via vegetative methods. Mech- nisms of the adventitious rooting and the regulation of rooting processes are the principles and techniques of plant propagation and improvement. Microstructures and fluctuations of phytohormones in the adventitious rooting were studied with the etiolated soft- wood shoots of Paeonia suffkuticosa ＇Yinfen Jinlin＇. There are no pre-primordia in the shoots of the cultivar. Adventitious roots are produced in five stages： shoot selection, primordium initiation, primordium growth, conducting tissue differentiation and root protru- sion. Primordia initiated in the cortex. The contents of the endogenous hormones, IAA, ABA and GA, were 5.842, 0.873 and 1.043 nmol·g^-1 FW on the bases of shoots, respectively. CTKs which included isopentenyl adenine （iPA）, zeatin riboside （ZR） and dihy- drozeatin riboside （DHZR） were 0.949, 0.695 and 2.034 nmol·g^-1 FW, respectively. DHZR is active among CTKs. The ratio of IAA to GA, CTK and ABA clearly increased at the stage of primordium initiation, while they showed low levels at the stages of primor- dium growth. The ratios were restored at the shoot levels at the stage of root protrusion. IBA provoked primordia initiation in the cortex, the vascular cambium, the pith and even in the callus induced on the base of shoots. ]AA levels in the treated shoots increased gradually to its highest level （three times of control） at the stage of conducting tissue differentiation. The ratios of IAA to GA, CTK and ABA clearly decreased at the stage of primordium initiation. The ratio of IAA to ABA is regulated at 10：1.

Cloning and Expression Analysis of an AP2/ERF Gene and Its Responses to Phytohormones and Abiotic Stresses in Rice

Ethylene response factors （ERFs） play important roles in response to plant biotic and abiotic stresses. In this study, a gene encoding a putative AP2/ERF domain-containing protein was isolated by screening a SSH cDNA library from rice and designated as Oryza sativa AP2/ERF-like protein （OsAP2LP） gene. OsAP2LP is 1491 bp in length, interrupted by seven introns, and encodes a putative protein of 348 amino acids. Temporal and spatial expression analysis showed that the OsAP2LP gene was preferentially expressed in roots, panicles, mature embryos and seeds in rice. Real-time quantitative PCR analysis indicated that the expression levels of the OsAP2LP gene were increased under the treatments of drought and gibberellin but decreased under the treatments of low temperature, salt, abscisic acid （ABA） and zeatin. Taken together, these results suggest that OsAP2LP might be involved in stress responses, and probably plays roles as a transcription regulator when plants response to cold, salt and drought stresses through ABA and gibberellin pathways.

Strigolactones interact with other phytohormones to modulate plant root growth and development

Strigolactones(SLs),which are biosynthesized mainly in roots,modulate various aspects of plant growth and development.Here,we review recent research on the role of SLs and their cross-regulation with auxin,cytokinin,and ethylene in the modulation of root growth and development.Under nutrientsufficient conditions,SLs regulate the elongation of primary roots and inhibit adventitious root formation in eudicot plants.SLs promote the elongation of seminal roots and increase the number of adventitious roots in grass plants in the short term,while inhibiting lateral root development in both grass and eudicot plants.The effects of SLs on the elongation of root hairs are variable and depend on plant species,growth conditions,and SL concentration.Nitrogen or phosphate deficiency induces the accumulation of endogenous SLs,modulates root growth and development.Genetic analyses indicate cross-regulation of SLs with auxin,cytokinin,and ethylene in regulation of root growth and development.We discuss the implications of these studies and consider their potential for exploiting the components of SL signaling for the design of crop plants with more efficient soil-resource utilization.

The regulatory network behind maize seed germination: Effects of temperature, water, phytohormones, and nutrients

Seed germination is the process by which an organism grows from a seed. It requires suitable conditions and environmental factors. Maize is one of the most important crops worldwide. Germination influences both final maize yield and quality. Seed germination is regulated by a complex gene network. It is also influenced by endogenous(phytohormones and nutrients) and exogenous(temperature and water)inputs, involving molecular networks only partly identified to date. This review describes current understanding of the influence of temperature, water, phytohormones, and nutrients in regulating maize seed germination, and indicates knowledge gaps that should be addressed.

Effect of ploidy level on expression of lycopene biosynthesis genes and accumulation of phytohormones during watermelon(Citrullus lanatus) fruit development and ripening

The difference between lycopene and phytohormone levels among diploid, triploid and tetraploid plants of two watermelon cultivars during fruit growth and ripening was studied. The expression pattern of five genes（phytoene synthase（PSY1）, phytoene desaturase（PDS）, ζ-carotene desaturase（ZDS）, carotenoid isomerase（CRTISO）, and lycopene β-cyclase（LCYB）） was analyzed in details. In red-fleshed cultivar Mimei, lycopene content increased rapidly from 25 to 35 days after pollination（DAP）, and then decreased at 40 DAP. Triploid and tetraploid fruit had higher levels of lycopene than diploid. Moreover, triploid tended to contain more lycopene than tetraploid during fruit growth and ripening stages. However, little amount of lycopene（0–2 mg kg–1 fresh weight（FW）） in yellow-fleshed cultivar Huangmei was found during all fruit development stages. In Mimei, transcript level of PSY1 was generally higher than the other four genes, and LCYB gene expression was the lowest among all five genes being tested. PSY1, CRTISO and LCYB genes showed higher transcript levels in polyploid than in diploid fruit. By contrast, in Huangmei, transcript level of LCYB was not the lowest, but only lower than that of PSY1. PSY1, CRTISO and LCYB genes showed higher expression levels in diploid than in polyploid fruit. In Mimei, the negative correlation between gibberellane（GA） content and lycopene accumulation was determined in all three different ploidy fruits, while a positive correlation was observed between abscisic acid（ABA） content and lycopene accumulation only in diploid watermelon. These results indicated that different lycopene contents in different ploidy watermelons is regulated by the differential transcription expression of the lycopene metabolic genes and phytohormones.

Interactive Effects of Drought Stress and Phytohormones or Polyamines on Growth and Yield of Two M(<i>Zea maize</i>L) Genotypes

Two maize genotypes (Nefertiti and Bashaier) were picked up from nine maize genotypes during the early vegetative growth (25 days) to be cultivated in open field upon the crop yield under the different drought stress levels (90,70,50,30) or under the interaction effect of drought stress and phytohormones or polyamines. According to the data of growth criteria, the maize genotype Nefertiti was found to be the most drought sensitive genotype, while the genotype Bashaier was found to be the most drought resistant genotype. Additionally while the photosynthetic pigments remained more or less unchanged in genotype Bashaier, their biosynthesis destroyed earlier in the drought sensitive genotype (Nefertiti). Also while the genotype Bashaier absorbed and accumulated a sufficient amount of mono and divalent cations (K+, Ca++ and Mg++), the genotype Nefertiti did not. Accordingly while the genotype Bashaier gave a crop yield up to 50% field capacity, the genotype Nefertiti gave a crop yield only up to 70% field capacity and failed to give a crop yield beyond this level. The interaction effect of drought stress and phytohormones and polyamines improved the all above characteristics. Interestingly each of these activators considerably improved the production of crop yield only in genotype Bashaier specially polyamines they produced more than 60% field capacity and at the level of 30% field capacity (the level which did not give crop yield in this genotype). However, phytohormones in generally did not make an important effect on the crop yield in genotype Nefertiti although they improved the dry matter production during the vegetative stages. Such situation seemed to be complicated and borne many questions to be studied in the future.

The Effect of Phytohormones on Lavender （Lavandula Angustiflia Mill.） Organogenesis

Lavender （L. angustifolia） is a genus of flowering plants in the mint family, Lamiaceae. It is an aromatic shrub with multiple stems growing 30 to 60 cm tall. It is native to Asia, Europe and Mediterranean regions and grows on hilly areas and coastlines. The evergreen leaves are narrow and long and covered in fine hairs, which normally contain the essential oils. The leaves are also pinnately toothed, or pinnate. The plant blooms between April and June, and flowers are purple produced on violet bracts. All parts of the plant have a strong and scented odor and a bitter taste. The flowers and leaves are used as an herbal medicine. Lavender essential oil is extracted by distilling flowers and leaves, Essential oil has higher levels of linalyl acetate （40%）, butyric acid, propionic acid, valeric acid, free linalool. Considering the lack of information about lavender tissue culture, the current experiment＇ was aimed to study the effect of phytohormones on lavender callus induction and organogenesis. The lavender explants （leaf and apical meristem） were cultured onto MS media supplemented with different phytohormones. According to the observations, 5 mg/L NAA and 5 mg/L KIN treatment caused leaf and root formation, which were originally derived t^om dense and green calli. The MS medium containing 5 mg/L IBA and 5 mg/L Kin was effective just on leafy explants so that explants formed into leaves after callus induction. Application of 5 mg/L NAA and 5 mg/L BAP on apical meristem explants produced shoot and root after callus induction. However, complete plants were produced after sub-culturing the samples. In conclusion, MS medium supplemented with 5 mg/L NAA and 5 mg/L BAP was selected as the best medium for lavender tissue culture.

Detection of seven phytohormones in peanut tissues by ultra-highperformance liquid chromatography-triple quadrupole tandem mass spectrometry

Development of highly sensitive and reliable method for detection of phytohormones is of great significance to study plant hormones and agricultural production.In this study,an ultra-high-performance liquid chromatography-mass spectrometry/mass spectrometry method was established for separation and quantification of trans-zeatin,trans-zeatin riboside,gibberellin A3,indol-3-acetic acid,salicylic acid,abscisic acid,and jasmonic acid(JA) without any label.The sepa ration was performed on an Agilent Explus Plus C18 column by using methanol and water as mobile phases with gradient elution.The target compounds were confirmed and quantified by mass spectrum via positive electrospray ionization for trans-zeatin,transzeatin riboside,indole-3-acetic acid,and via negative electrospray ionization for gibberellin3,salicylic acid,abscisic acid,and JA.The limits of detection ranged from 0.0127 ng L^-1 for gibberellin A3(GA3) to 33.26 ng L^-1 for JA and were lower than the currently reported values in literature.The proposed method was applied for qualitative and quantitative analyses of phytohormones in peanut gynophores and pods.The recoveries of the spiked phytohormones ranged from 80.20 to102.56%.The contents of seven endogenous hormones varied specifically in different development stages of peanuts.This study provides a highly sensitive and selective detection method for hormones and elucidates the growth and development of the gynophore and peanut fruit,which are controlled by seven endogenous hormones.

Expression and functional analyses of the mitogen-activated protein kinase (MPK) cascade genes in response to phytohormones in wheat ( Triticum aestivum L.)

Mitogen-activated protein kinase （MPK） cascades consist of a set of kinase types （MPKKKs, MPKKs, MPKs） to establish conserved signal-transducing modules mediating plant growth, development as well as responses to internal and external cues. In this study, the expression patterns of six MPKKK, two MPKK, and 11 MPK genes in wheat in responses to external treatments of phytohormones, including naphthylacetic acid （NAA）, abscisic acid （ABA）, 6-benzyladenine （6-BA）, gibber- ellin （GA3）, salisylic acid （SA）, jasmonic acid （JA）, and ethylene （ETH）, were investigated. Expression analysis revealed that several of the MPK cascade genes are responses to the external phytohormone signaling. Of which, TaMPKKKA;3 is induced by 6-BA and NAA while TaMPK4 repressed by ETH, GA3, SA, and JA; TaMPKKKA, TaMPKKKA;3 and TaMPK1 are down-regulated by ETH and GA3whereas TaMPK9 and TaMPK12 repressed by ETH and JA in addition that TaMPK12 also repressed by GA3; TaMPK12;1 is down-regulated by ABA, GA3 and SA while TaMPK17 repressed by all exogenous phytonormones examined. TaMPK4, a MPK type gene previously characterized to mediate tolerance to phosphate （Pi） deprivation, was functionally evaluated for its role in mediation of responses of plants to exogenous GA3, ETH, SA, and JA. Results indicated that overexpression and antisense expression of TaMPK4 in tobacco dramatically modify the growth of seedlings upon treatments of GA3, SA and JA, in which the overexpressors behaved deteriorated growth feature whereas the seedlings with antisense expression of TaMPK4 exhibited improved seedling phenotype. The growth behaviors in lines overexpressing or antisensely expressing TaMPK4 are closely associated with the biomass and the corresponding hormone-associated parameters. These results demonstrated that TaMPK4 acts as a critical player in mediating the phyto- hormone signaling. Our findings have identified the phytohormone-responsive MPK cascade genes in wheat and provided a connection between the phytohormone-mediated responses and the MPK cascade pathways.

Gamma-aminobutyric acid interactions with phytohormones and its role in modulating abiotic and biotic stress in plants

Gamma-aminobutyric acid(GABA),a ubiquitous non-protein 4-carbon amino acid present in both prokaryotic and eukaryotic organisms.It is conventionally recognized as a neurotransmitter in mammals and plays a crucial role in plants.The context of this review centers on the impact of GABA in mitigating abiotic stresses induced by climate change,such as drought,salinity,heat,and heavy metal exposure.Beyond its neurotransmitter role,GABA emerges as a key player in diverse metabolic processes,safeguarding plants against multifaceted abiotic as well as biotic challenges.This comprehensive exploration delves into the GABA biosynthetic pathway,its transport mechanisms,and its intricate interplay with various abiotic stresses.The discussion extends to the nuanced relationship between GABA and phytohormones during abiotic stress acclimation,offering insights into the strategic development of mitigation strategies against these stresses.The delineation of GABA’s crosstalk with phytohormones underscores its pivotal role in formulating crucial strategies for abiotic stress alleviation in plants.

植物激素对棉花蕾铃脱落的调控研究进展

棉花蕾铃脱落是一个普遍存在的现象,有对逆境环境胁迫的主动适应性脱落,也有因品种遗传特性、环境条件、栽培措施以及生物和非生物胁迫被动的受损脱落。蕾铃脱落直接影响着棉花的产量,国内外现有公开报道多集中于20世纪50、60年代关于乙烯和脱落酸对棉花蕾铃脱落影响的初步发现。结合其他植物的研究结果来看,蕾铃脱落似乎与生长素、赤霉素和细胞分裂素等促生长类激素的下降以及乙烯和脱落酸等抑制生长类激素的升高密切相关,激素在植物体内不仅介导新陈代谢过程,还协调着与信号通路相关的调控因子,在脱落过程中起着关键作用。本文从植物激素调控入手,综述了近年来包括脱落区形成和作用的分子调控机制以及各激素在棉花蕾铃脱落以及其他植物(生殖)器官脱落过程中的响应和调控机制等。发现目前以棉花蕾铃脱落为对象的研究非常匮乏,且多集中于少数激素对棉花生殖生长影响的有限研究,缺乏对导致蕾铃脱落的深层次机制的探究和解析。因此,未来研究方向应着重于探究棉花蕾铃脱落的遗传基础、发掘新的抗脱落基因资源和培育抗脱落棉花品种,同时加强在以棉花为模型植物下,蕾铃脱落与植物激素调节的关系研究,为提高棉花产量提供理论依据和技术支持。

Leaf stage-associated resistance is correlated with phytohormones in a pathosystem-dependen manner

It has been reported in several pathosystems that disease resistance can vary in leaves at different stages. However, how general this leaf stage-associated resistance is, and the molecular mechanism（s） underly- ing it, remain largely unknown. Here, we investigated the effect of leaf stage on basal resistance, effector- triggered immunity （ETI） and nonhost resistance, using eight pathosystems involving the hosts Arabidopsis thaliana, Nicotiana tabacum, and N. benthamiana and the pathogens Sclerotinia sclerotiorum, Pseudomonas syringae pv. tabaci, P. syringae pv. tomato DC3000, and Xanthomonas oryzae pv. oryzae （Xoo）. We show evidence that leaf stage-associated resistance exists ubiquitously in plants, but with varying intensity at different stages in diverse pathosystems. Microarray expression profiling assays demonstrated that hundreds of genes involved indefense responses, phytohormone biosynthesis and signaling, and calcium signaling, were differentially expressed between leaves at different stages. The Arabidopsis mutants sid1, sid2-3, ein2, jar1-1, abal and aao3 lost leaf stage-associated resistance to S. sclerotiorum, and the mutants abal and sid2-3 were affected in leaf stage-associated RPS2/AvrRpt2＋-con- ferred ETI, whereas only the mutant sid2-3 influenced leaf stage-associated nonhost resistance to Xoo. Our results reveal that the phytohormones salicylic acid, ethylene, jasmonic acid and abscisic acid likely play an essential, but pathosystem-dependent, role in leaf stage- associated resistance.