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1.
J Mol Evol ; 89(9-10): 665-677, 2021 12.
Artigo em Inglês | MEDLINE | ID: mdl-34757471

RESUMO

Plant hormone cytokinins are important regulators of plant development, response to environmental stresses and interplay with other plant hormones. Cytokinin dehydrogenases (CKXs) are proteins responsible for the irreversible break-down of cytokinins to the adenine and aldehyde. Even though plant CKXs have been extensively studied, homologous proteins from other taxa remain mainly uncharacterised. Here we present our study on the molecular evolution and divergence of the CKX from bacteria, fungi, amoeba and viridiplantae. Although CKXs are present in eukaryotes and prokaryotes, they are missing in algae and metazoan taxa. The prevalent domain architecture consists of the FAD-binding and cytokinin binding domains, whereas some bacteria appear to have only cytokinin binding domain proteins. The CKXs play important role in the various aspects of plant life including control of plant development, response to biotic and abiotic stress, influence nutrition. Results of our study suggested that CKX originates from the FAD-linked C-terminal oxidase and has a defence-oriented function. The obtained results significantly extend the current understanding of the cytokinin dehydrogenases structure-function from the relationship to homologues from other taxa and provide a starting point baseline for their future functional characterization.


Assuntos
Citocininas , Regulação da Expressão Gênica de Plantas , Animais , Oxirredutases/genética , Oxirredutases/metabolismo , Estresse Fisiológico
2.
Nat Commun ; 12(1): 5816, 2021 10 05.
Artigo em Inglês | MEDLINE | ID: mdl-34611150

RESUMO

During vegetative growth plants pass from a juvenile to an adult phase causing changes in shoot morphology. This vegetative phase change is primarily regulated by the opposite actions of two microRNAs, the inhibitory miR156 and the promoting miR172 as well as their respective target genes, constituting the age pathway. Here we show that the phytohormone cytokinin promotes the juvenile-to-adult phase transition through regulating components of the age pathway. Reduction of cytokinin signalling substantially delayed the transition to the adult stage. tZ-type cytokinin was particularly important as compared to iP- and the inactive cZ-type cytokinin, and root-derived tZ influenced the phase transition significantly. Genetic and transcriptional analyses indicated the requirement of SQUAMOSA PROMOTER BINDING PROTEIN-LIKE (SPL) transcription factors and miR172 for cytokinin activity. Two miR172 targets, TARGET OF EAT1 (TOE1) and TOE2 encoding transcriptional repressors were necessary and sufficient to mediate the influence of cytokinin on vegetative phase change. This cytokinin pathway regulating plant aging adds to the complexity of the regulatory network controlling the juvenile-to-adult phase transition and links cytokinin to miRNA action.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Citocininas/farmacologia , MicroRNAs/metabolismo , Arabidopsis/efeitos dos fármacos , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , MicroRNAs/genética
3.
PLoS One ; 16(9): e0250678, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34473720

RESUMO

Apricot bud gall mite, Acalitus phloeocoptes (Nalepa), is a destructive arthropod pest that causes significant economic losses to apricot trees worldwide. The current study explores the ways to understand the mode of dispersal of A. phloeocoptes, the development and ultrastructure of apricot bud gall, and the role of phytohormones in the formation of the apricot bud galls. The results demonstrated that the starch granules in the bud axon were extended at the onset of the attack. During the later stages of the attack, the cytoplasm was found to deteriorate in infected tissues. Furthermore, we have observed that the accumulation of large amounts of cytokinin (zeatin, ZT) and auxin (indoleacetic acid, IAA) led to rapid bud proliferation during rapid growth period, while abscisic acid (ABA) controls the development of gall buds and plays a vital role in gall bud maturity. The reduction of gibberellic acid (GA3) content led to rapid lignification at the later phase of bud development. Overall, our results have revealed that the mechanism underlying the interaction of apricot bud gall with its parasite and have provided reliable information for designing valuable Apricot breeding programs. This study will be quite useful for pest management and will provide a comprehensive evaluation of ecology-based cost-effective control, life history and demographic parameters of A. phloeocoptes.


Assuntos
Ácaros/patogenicidade , Reguladores de Crescimento de Plantas/metabolismo , Prunus armeniaca/parasitologia , Amido/metabolismo , Ácido Abscísico/metabolismo , Animais , Citocininas/metabolismo , Feminino , Giberelinas/metabolismo , Interações Hospedeiro-Parasita , Ácidos Indolacéticos/metabolismo , Masculino , Melhoramento Vegetal , Prunus armeniaca/fisiologia
4.
Int J Mol Sci ; 22(18)2021 Sep 08.
Artigo em Inglês | MEDLINE | ID: mdl-34575868

RESUMO

Temperature is an important factor that largely affects the patterns of shoot branching in plants. However, the effect and mechanism of temperature on axillary bud development in chrysanthemum remains poorly defined. The purpose of the present study is to investigate the effect of high temperature on the axillary bud growth and the mechanism of axillary bud formation in chrysanthemum. Decapitation experiments combined with the transcriptome analysis were designed. Results showed that the axillary bud length was significantly inhibited by high temperature. Decapitation of primary shoot (primary decapitation) resulted in slower growth of axillary buds (secondary buds) under 35 °C. However, secondary decapitation resulted in complete arrest of tertiary buds at high temperature. These results demonstrated that high temperature not only inhibited axillary bud formation but also retarded bud outgrowth in chrysanthemum. Comparative transcriptome suggested differentially expressed gene sets and identified important modules associated with bud formation. This research helped to elucidate the regulatory mechanism of high temperature on axillary bud growth, especially bud formation in chrysanthemum. Meanwhile, in-depth studies of this imperative temperature signaling can offer the likelihood of vital future applications in chrysanthemum breeding and branching control.


Assuntos
Chrysanthemum/embriologia , Chrysanthemum/genética , Chrysanthemum/metabolismo , Regulação da Expressão Gênica de Plantas , Melhoramento Vegetal , Reguladores de Crescimento de Plantas/genética , Citocininas/genética , Perfilação da Expressão Gênica , Genes de Plantas , Homeostase , Temperatura Alta , Ácidos Indolacéticos , Proteínas de Plantas/genética , Brotos de Planta/genética , RNA-Seq , Sacarose/química , Transcriptoma
5.
Planta ; 254(4): 65, 2021 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-34487248

RESUMO

MAIN CONCLUSION: Enhanced levels of indole-3-acetic and raised auxin to cytokinin ratios in the stem base contribute to the positive acropetal gradient in rooting capacity of leafy single-node stem cuttings of rose. Cuttings excised from different nodal positions in stock plants can differ in subsequent adventitious root formation. We investigated the involvement of the auxin-cytokinin balance in position-affected rooting of Rosa hybrida. Leafy single-node stem cuttings of two rose cultivars were excised from top versus bottom positions. Concentrations of IAA and cytokinins were monitored in the bud region and the stem base during 8 days after planting using chromatography-MS/MS technology. The effects of nodal position and external supply of indole-butyric acid on rooting were analyzed. Most cytokinins increased particularly in the bud region and peaked at day two before the bud break was recorded. IAA increased in both tissues between day one and day eight. Top versus bottom cuttings revealed higher levels of isopentenyladenosine (IPR) in both tissues as well as higher concentrations of IAA and a higher ratio of IAA to cytokinins particularly in the stem base. The dynamic of hormones and correlation analysis indicated that the higher IPR contributed to the enhanced IAA in the bud region which served as auxin source for the auxin homeostasis in the stem base, where IAA determined the auxin-cytokinin balance. Bottom versus top cuttings produced lower numbers and lengths of roots, whereas this deficit was counterbalanced by auxin application. Further considering other studies of rose, it is concluded that cytokinin-, sucrose- and zinc-dependent auxin biosynthesis in the outgrowing buds is an important factor that contributes to the enhanced IAA levels and auxin/cytokinin ratios in the stem base of apical cuttings, promoting root induction.


Assuntos
Citocininas , Rosa , Homeostase , Ácidos Indolacéticos , Raízes de Plantas , Espectrometria de Massas em Tandem
6.
Funct Plant Biol ; 48(11): 1100-1112, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-34551855

RESUMO

Wounding induces a cascade of correlative physiological responses that lead to the repair of damaged tissue. In this study, the effect of wounding on suberin, endogenous hormones and their metabolic genes expression was observed during the wound healing of kiwifruit (Actinidia chinensis Planch.). In addition, the role of abscisic acid (ABA) in wound suberisation was investigated by analysing the coordinated regulation between ABA and other hormones. The wound healing process in kiwifruit could be divided into two stages including: (1) initial accumulation of suberin polyphenolic (SPP) and long carbon chain suberin polyaliphatic monomers (LSPA) before 24h; and (2) massive synthesis of SPP and very long carbon chain suberin polyaliphatic monomers (VLSPA) after 24h. ABA content rapidly increased and induced the jasmonic acid (JA) biosynthesis at the early stage of wound healing. ABA level gradually decreased with the expression of AchCYP707A genes, while the contents of trans-zeatin (t-ZT) and indole-3-acetic acid (IAA) steadily increased at the late stage of wound healing. Exogenous ABA stimulated JA and suberin monomers accumulation, but suppressed both t-ZT and IAA biosynthesis. The role of ABA in wound healing of kiwifruit might be involved in the coordination of both JA-mediated suberin monomers biosynthesis and t-ZT- and IAA-mediated formation of suberised cells via an interaction mechanism.


Assuntos
Ácido Abscísico , Actinidia , Actinidia/metabolismo , Ciclopentanos , Citocininas , Regulação da Expressão Gênica de Plantas , Ácidos Indolacéticos , Oxilipinas , Proteínas de Plantas/genética
7.
Int J Mol Sci ; 22(17)2021 Aug 26.
Artigo em Inglês | MEDLINE | ID: mdl-34502163

RESUMO

Garlic (Allium sativum L.) is an important vegetable and is cultivated and consumed worldwide for its economic and medicinal values. Garlic cloves, the major reproductive and edible organs, are derived from the axillary meristems. KNOTTED-like homeobox (KNOX) proteins, such as SHOOT MERISTEM-LESS (STM), play important roles in axillary meristem formation and development. However, the KNOX proteins in garlic are still poorly known. Here, 10 AsKNOX genes, scattered on 5 of the 8 chromosomes, were genome-wide identified and characterized based on the newly released garlic genome. The typical conserved domains of KNOX proteins were owned by all these 10 AsKNOX homologs, which were divided into two Classes (Class I and Class II) based on the phylogenetic analysis. Prediction and verification of the subcellular localizations revealed the diverse subcellular localization of these 10 AsKNOX proteins. Cis-element prediction, tissue expression analysis, and expression profilings in responding to exogenous GA3 and 6-BA showed the potential involvement of AsKNOX genes in the gibberellin and cytokinin signaling pathways. Overall, the results of this work provided a better understanding of AsKNOX genes in garlic and laid an important foundation for their further functional studies.


Assuntos
Citocininas/farmacologia , Alho/genética , Giberelinas/farmacologia , Proteínas de Homeodomínio/genética , Proteínas de Plantas/genética , Alho/efeitos dos fármacos , Alho/metabolismo , Proteínas de Homeodomínio/metabolismo , Proteínas de Plantas/metabolismo , Transdução de Sinais
8.
J Pharm Biomed Anal ; 206: 114363, 2021 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-34521037

RESUMO

Among essential phytohormones playing a pivotal role in regulating growth and development, ortho-topolin riboside (oTR) exerts the most substantial anti-tumor potency in various cancer cell lines. This study was designed to establish a quantitative determination method for oTR in mouse plasma using high-performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS), to validate the analytical method including stability, and to characterise its pharmacokinetic behaviour in mice. After simple protein precipitation with acetonitrile including kinetin riboside (internal standard), oTR was eluted on a reversed-phase column using a mobile phase of water and acetonitrile (3:7 v/v, including 0.1% formic acid). The protonated precursor ion [M+H]+ and major fragment ion were confirmed at m/z 374.06 and 241.99 for oTR, and 348.23 and 216.06 for the IS, respectively. oTR was stable under bench and storage conditions. The analytical method met the criteria of FDA-validated bioanalytical methods and was successfully applied to a pharmacokinetic study for the first time following oral, subcutaneous, and intravenous administrations. While oTR was merely absorbed by an oral route, 90% of the absolute subcutaneous bioavailability was observed.


Assuntos
Citocininas , Espectrometria de Massas em Tandem , Administração Oral , Animais , Disponibilidade Biológica , Cromatografia Líquida de Alta Pressão , Camundongos , Reprodutibilidade dos Testes
9.
Plant Physiol Biochem ; 167: 763-770, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34530321

RESUMO

Phytohormones play important roles in controlling leaf size and in the modulation of various stress responses, including drought. In this study, hormone profiling analyses by ultra high-performance liquid chromatography coupled to electrospray ionization tandem mass spectrometry (UHPLC-MS/MS) was performed in leaves collected at three stages of active leaf growth to unravel which phytohormones modulate leaf size in sesame (Sesamum indicum L.) plants, an important oil-rich crop. Furthermore, endogenous contents of phytohormones were measured in parallel to various stress markers in sesame plants exposed to mild water deficit conditions by withholding water in potted plants for one week. Results revealed a major role of cytokinins and auxin in the modulation of leaf growth in sesame plants (which increased by 21.5 and 2.1-fold, respectively, with leaf growth), as well as a putative antagonistic response between jasmonic acid and salicylic acid during leaf development. Furthermore, growth arrest during water deficit stress appeared to be modulated by cytokinins, the endogenous contents of which decreased (by 48%) in parallel with ABA increases (by 59%). Reductions in the contents of the active cytokinin trans-zeatin occurred in parallel with increases in isopentenyladenine contents under drought, which suggests a partial metabolic limitation in cytokinin biosynthesis in leaves upon water deficit stress. These results provide useful information for the hormonal modulation of leaf size and the improvement of leaf growth and production in sesame plants through manipulation of the levels of key regulatory phytohormones.


Assuntos
Citocininas , Sesamum , Reguladores de Crescimento de Plantas , Folhas de Planta , Espectrometria de Massas em Tandem
10.
Plant Physiol Biochem ; 167: 785-794, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34530323

RESUMO

Cadmium (Cd) is one of the most widespread polluting heavy metals in both terrestrial and aquatic environments and represents an extremely significant pollutant causing severe environmental and social problems due to its high toxicity and large solubility in water. In plants, the root is the first organ that get in contact with Cd. It is absorbed by the root system and translocated to the shoot and leaves through xylem loading, causing a variety of genetic, biochemical, and physiological damages. Cd inhibits both the root and shoot growth, but the mechanisms underlying this inhibition remain elusive. In this context in the present work we focused the attention on the effects of Cd on meristem size and organization of both shoot and root. To this aim morpho-histological and molecular analyses were carried out on 5 days old seedlings exposed or not to Cd (100 µM and 150 µM for 24) of wild type and transgenic lines expressing molecular markers with an important role in shoot and root pattern organization. More precisely, we monitored the expression pattern of WUS/CLV3 and WOX5 transcription factors involved in the establishment and maintenance of stem cell niche and the control of meristem size and of TCSn::GFP cytokinin-sensitive sensor as relevant components of hormone circuit controlling shoot and root growth. The results highlighted that the treatments with Cd impacts shoot and root size and shape by altering the paralogous WOX genes expression via cytokinin accumulation.


Assuntos
Proteínas de Arabidopsis , Arabidopsis , Arabidopsis/genética , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Cádmio/toxicidade , Citocininas , Regulação da Expressão Gênica de Plantas , Proteínas de Homeodomínio/genética , Meristema/genética , Meristema/metabolismo , Brotos de Planta/genética , Brotos de Planta/metabolismo
11.
Planta ; 254(3): 45, 2021 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-34365553

RESUMO

MAIN CONCLUSION: Riboside type cytokinins are key components in cytokinin metabolism, transport, and sensitivity, making them important functional signals in plant growth and development and environmental stress responses. Cytokinin (CKs) are phytohormones that regulate multiple processes in plants and are critical for agronomy, as they are involved in seed filling and plant responses to biotic and abiotic stress. Among the over 30 identified CKs, there is uncertainty about the roles of many of the individual CK structural forms. Cytokinin free bases (CKFBs), have been studied in great detail, but, by comparison, roles of riboside-type CKs (CKRs) in CK metabolism and associated signaling pathways and their distal impacts on plant physiology remain largely unknown. Here, recent findings on CKR abundance, transport and localization, are summarized, and their importance in planta is discussed. The history of CKR analyses is reviewed, in the context of the determination of CK metabolic pathways, and research on CKR affinity for CK receptors, all of which yield essential insights into their functions. Recent studies suggest that CKR forms are a lot more than a group of transport CKs and, beyond this, they play important roles in plant development and responses to environmental stress. In this context, this review discusses the involvement of CKRs in plant development, and highlight the less anticipated functions of CKRs in abiotic stress tolerance. Based on this, possible mechanisms for CKR modes of action are proposed and experimental approaches to further uncover their roles and future biotechnological applications are suggested.


Assuntos
Citocininas , Reguladores de Crescimento de Plantas , Desenvolvimento Vegetal , Plantas , Estresse Fisiológico
12.
Funct Plant Biol ; 48(9): 889-904, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-34366001

RESUMO

Using pea as our model crop, we sought to understand the regulatory control over the import of sugars and amino acids into the developing seeds and its importance for seed yield and quality. Transgenic peas simultaneously overexpressing a sucrose transporter and an amino acid transporter were developed. Pod walls, seed coats, and cotyledons were analysed separately, as well as leaves subtending developing pods. Sucrose, starch, protein, free amino acids, and endogenous cytokinins were measured during development. Temporal gene expression analyses (RT-qPCR) of amino acid (AAP), sucrose (SUT), and SWEET transporter family members, and those from cell wall invertase, cytokinin biosynthetic (IPT) and degradation (CKX) gene families indicated a strong effect of the transgenes on gene expression. In seed coats of the double transgenics, increased content and prolonged presence of cytokinin was particularly noticeable. The transgenes effectively promoted transition of young sink leaves into source leaves. We suggest the increased flux of sucrose and amino acids from source to sink, along with increased interaction between cytokinin and cell wall invertase in developing seed coats led to enhanced sink activity, resulting in higher cotyledon sucrose at process pea harvest, and increased seed number and protein content at maturity.


Assuntos
Citocininas , Ervilhas , Sistemas de Transporte de Aminoácidos , Ervilhas/genética , Sementes/genética , Sacarose
13.
Int J Mol Sci ; 22(15)2021 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-34360972

RESUMO

Auxins and cytokinins create versatile regulatory network controlling virtually all aspects of plant growth and development. These hormonal systems act in close contact, synergistically or antagonistically, determining plant phenotype, resistance and productivity. However, the current knowledge about molecular interactions of these systems is still scarce. Our study with potato plants aimed at deciphering potential interactions between auxin and cytokinin signaling pathways at the level of respective gene expression. Potato plants grown on sterile medium with 1.5% (vegetation) or 5% (tuberization) sucrose were treated for 1 h with auxin or cytokinin. Effects of these two hormones on expression profiles of genes belonging to main signaling pathways of auxin and cytokinin were quantified by RT-qPCR. As a result, several signaling genes were found to respond to auxin and/or cytokinin by up- or down-regulation. The observed effects were largely organ-specific and depended on sucrose content. Auxin strongly reduced cytokinin perception apparatus while reciprocal cytokinin effect was ambiguous and sucrose-dependent. In many cases, functional clustering of genes of the same family was observed. Promoters in some clusters are enriched with canonic hormone-response cis-elements supporting their direct sensitivity to hormones. Collectively, our data shed new light on the crosstalk between auxin- and cytokinin signaling pathways.


Assuntos
Citocininas/metabolismo , Ácidos Indolacéticos/metabolismo , Transdução de Sinais , Solanum tuberosum/metabolismo , Genes de Plantas , Desenvolvimento Vegetal , Solanum tuberosum/genética , Solanum tuberosum/crescimento & desenvolvimento , Sacarose/metabolismo
14.
Int J Mol Sci ; 22(16)2021 Aug 09.
Artigo em Inglês | MEDLINE | ID: mdl-34445260

RESUMO

De novo shoot organogenesis (DNSO) is a procedure commonly used for the in vitro regeneration of shoots from a variety of plant tissues. Shoot regeneration occurs on nutrient media supplemented with the plant hormones cytokinin (CK) and auxin, which play essential roles in this process, and genes involved in their signaling cascades act as master regulators of the different phases of shoot regeneration. In the last 20 years, the genetic regulation of DNSO has been characterized in detail. However, as of today, the CK and auxin signaling events associated with shoot regeneration are often interpreted as a consequence of these hormones simply being present in the regeneration media, whereas the roles for their prior uptake and transport into the cultivated plant tissues are generally overlooked. Additionally, sucrose, commonly added to the regeneration media as a carbon source, plays a signaling role and has been recently shown to interact with CK and auxin and to affect the efficiency of shoot regeneration. In this review, we provide an integrative interpretation of the roles for CK and auxin in the process of DNSO, adding emphasis on their uptake from the regeneration media and their interaction with sucrose present in the media to their complex signaling outputs that mediate shoot regeneration.


Assuntos
Citocininas/metabolismo , Ácidos Indolacéticos/metabolismo , Organogênese Vegetal , Reguladores de Crescimento de Plantas/metabolismo , Brotos de Planta/metabolismo , Brotos de Planta/citologia
15.
Int J Mol Sci ; 22(14)2021 Jul 07.
Artigo em Inglês | MEDLINE | ID: mdl-34298928

RESUMO

Salt stress seriously restricts crop yield and quality, leading to an urgent need to understand its effects on plants and the mechanism of plant responses. Although phytohormones are crucial for plant responses to salt stress, the role of phytohormone signal transduction in the salt stress responses of stress-resistant species such as Sophora alopecuroides has not been reported. Herein, we combined transcriptome and metabolome analyses to evaluate expression changes of key genes and metabolites associated with plant hormone signal transduction in S. alopecuroides roots under salt stress for 0 h to 72 h. Auxin, cytokinin, brassinosteroid, and gibberellin signals were predominantly involved in regulating S. alopecuroides growth and recovery under salt stress. Ethylene and jasmonic acid signals may negatively regulate the response of S. alopecuroides to salt stress. Abscisic acid and salicylic acid are significantly upregulated under salt stress, and their signals may positively regulate the plant response to salt stress. Additionally, salicylic acid (SA) might regulate the balance between plant growth and resistance by preventing reduction in growth-promoting hormones and maintaining high levels of abscisic acid (ABA). This study provides insight into the mechanism of salt stress response in S. alopecuroides and the corresponding role of plant hormones, which is beneficial for crop resistance breeding.


Assuntos
Estresse Salino/genética , Transdução de Sinais/genética , Sophora/genética , Ácido Abscísico/metabolismo , Brassinosteroides/metabolismo , Citocininas/genética , Etilenos/metabolismo , Perfilação da Expressão Gênica/métodos , Regulação da Expressão Gênica de Plantas/genética , Ácidos Indolacéticos/metabolismo , Melhoramento Vegetal/métodos , Reguladores de Crescimento de Plantas/genética , Proteínas de Plantas/genética , Ácido Salicílico/metabolismo , Tolerância ao Sal/genética , Sophora/metabolismo , Estresse Fisiológico/genética , Transcriptoma/genética , Regulação para Cima/genética
16.
Plant Mol Biol ; 106(6): 555-567, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34275101

RESUMO

KEY MESSAGE: Root-specific expression of a cytokinin-degrading CKX gene in maize roots causes formation of a larger root system leading to higher element content in shoot organs. The size and architecture of the root system is functionally relevant for the access to water and soil nutrients. A great number of mostly unknown genes are involved in regulating root architecture complicating targeted breeding of plants with a larger root system. Here, we have explored whether root-specific degradation of the hormone cytokinin, which is a negative regulator of root growth, can be used to genetically engineer maize (Zea mays L.) plants with a larger root system. Root-specific expression of a CYTOKININ OXIDASE/DEHYDROGENASE (CKX) gene of Arabidopsis caused the formation of up to 46% more root dry weight while shoot growth of these transgenic lines was similar as in non-transgenic control plants. The concentration of several elements, in particular of those with low soil mobility (K, P, Mo, Zn), was increased in leaves of transgenic lines. In kernels, the changes in concentration of most elements were less pronounced, but the concentrations of Cu, Mn and Zn were significantly increased in at least one of the three independent lines. Our data illustrate the potential of an increased root system as part of efforts towards achieving biofortification. Taken together, this work has shown that root-specific expression of a CKX gene can be used to engineer the root system of maize and alter shoot element composition.


Assuntos
Proteínas de Arabidopsis/genética , Citocininas/metabolismo , Proteínas de Membrana/genética , Oxirredutases atuantes sobre Doadores de Grupo CH-NH/genética , Folhas de Planta/genética , Raízes de Plantas/genética , Zea mays/genética , Arabidopsis/genética , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Cobre/metabolismo , Regulação da Expressão Gênica de Plantas , Engenharia Genética/métodos , Manganês/metabolismo , Proteínas de Membrana/metabolismo , Minerais/metabolismo , Oxirredutases atuantes sobre Doadores de Grupo CH-NH/metabolismo , Folhas de Planta/metabolismo , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/metabolismo , Brotos de Planta/genética , Brotos de Planta/metabolismo , Plantas Geneticamente Modificadas , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Transgenes/genética , Zea mays/crescimento & desenvolvimento , Zea mays/metabolismo , Zinco/metabolismo
17.
Nat Commun ; 12(1): 4321, 2021 07 14.
Artigo em Inglês | MEDLINE | ID: mdl-34262040

RESUMO

Symmetry establishment is a critical process in the development of multicellular organs and requires careful coordination of polarity axes while cells actively divide within tissues. Formation of the apical style in the Arabidopsis gynoecium involves a bilateral-to-radial symmetry transition, a stepwise process underpinned by the dynamic distribution of the plant morphogen auxin. Here we show that SPATULA (SPT) and the HECATE (HEC) bHLH proteins mediate the final step in the style radialisation process and synergistically control the expression of adaxial-identity genes, HOMEOBOX ARABIDOPSIS THALIANA 3 (HAT3) and ARABIDOPSIS THALIANA HOMEOBOX 4 (ATHB4). HAT3/ATHB4 module drives radialisation of the apical style by promoting basal-to-apical auxin flow and via a negative feedback mechanism that finetune auxin distribution through repression of SPT expression and cytokinin sensitivity. Thus, this work reveals the molecular basis of axes-coordination and hormonal cross-talk during the sequential steps of symmetry transition in the Arabidopsis style.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/crescimento & desenvolvimento , Proteínas de Homeodomínio/metabolismo , Arabidopsis/genética , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Transporte Biológico , Citocininas/metabolismo , Retroalimentação Fisiológica , Flores/genética , Flores/crescimento & desenvolvimento , Flores/metabolismo , Regulação da Expressão Gênica de Plantas , Proteínas de Homeodomínio/genética , Ácidos Indolacéticos/metabolismo
18.
New Phytol ; 232(4): 1582-1590, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34254310

RESUMO

The hemiparasitic plant Phtheirospermum japonicum (Phtheirospermum) is a nutritional specialist that supplements its nutrient requirements by parasitizing other plants through haustoria. During parasitism, the Phtheirospermum haustorium transfers hypertrophy-inducing cytokinins (CKs) to the infected host root. The CK biosynthesis genes required for haustorium-derived CKs and the induction of hypertrophy are still unknown. We searched for haustorium-expressed isopentenyltransferases (IPTs) that catalyze the first step of CK biosynthesis, confirmed the specific expression by in vivo imaging of a promoter-reporter, and further analyzed the subcellular localization, the enzymatic function and contribution to inducing hypertrophy by studying CRISPR-Cas9-induced Phtheirospermum mutants. PjIPT1a was expressed in intrusive cells of the haustorium close to the host vasculature. PjIPT1a and its closest homolog PjIPT1b located to the cytosol and showed IPT activity in vitro with differences in substrate specificity. Mutating PjIPT1a abolished parasite-induced CK responses in the host. A homolog of PjIPT1a also was identified in the related weed Striga hermonthica. With PjIPT1a, we identified the IPT enzyme that induces CK responses in Phtheirospermum japonicum-infected Arabidopsis roots. We propose that PjIPT1a exemplifies how parasitism-related functions evolve through gene duplications and neofunctionalization.


Assuntos
Arabidopsis , Orobanchaceae , Alquil e Aril Transferases , Arabidopsis/genética , Citocininas , Regulação da Expressão Gênica de Plantas , Raízes de Plantas
19.
Cells ; 10(6)2021 06 04.
Artigo em Inglês | MEDLINE | ID: mdl-34199921

RESUMO

Somatic embryogenesis is the formation of a plant embryo from a cell other than the product of gametic fusion. The need to recognize the determinants of somatic cell fate has prompted investigations on how endogenous factors of donor tissues can determine the pattern of somatic embryo origin. The undertaking of this study was enabled by the newly developed experimental system of somatic embryogenesis of the tree fern Cyathea delgadii Sternb., in which the embryos are produced in hormone-free medium. The contents of 89 endogenous compounds (such as sugars, auxins, cytokinins, gibberellins, stress-related hormones, phenolic acids, polyamines, and amino acids) and cytomorphological features were compared between two types of explants giving rise to somatic embryos of unicellular or multicellular origin. We found that a large content of maltose, 1-kestose, abscisic acid, biologically active gibberellins, and phenolic acids was characteristic for single-cell somatic embryo formation pattern. In contrast, high levels of starch, callose, kinetin riboside, arginine, and ethylene promoted their multicellular origin. Networks for visualization of the relations between studied compounds were constructed based on the data obtained from analyses of a Pearson correlation coefficient heatmap. Our findings present for the first time detailed features of donor tissue that can play an important role in the somatic-to-embryogenic transition and the somatic embryo origin.


Assuntos
Citocininas/farmacologia , Gleiquênias/metabolismo , Técnicas de Embriogênese Somática de Plantas , Gleiquênias/citologia
20.
Cells ; 10(7)2021 06 29.
Artigo em Inglês | MEDLINE | ID: mdl-34209875

RESUMO

The plant hormone cytokinin (CK) plays central roles in plant development and throughout plant life. The perception of CKs initiating their signaling cascade is mediated by histidine kinase receptors (AHKs). Traditionally thought to be perceived mostly at the endoplasmic reticulum (ER) due to receptor localization, CK was recently reported to be perceived at the plasma membrane (PM), with CK and its AHK receptors being trafficked between the PM and the ER. Some of the downstream mechanisms CK employs to regulate developmental processes are unknown. A seminal report in this field demonstrated that CK regulates auxin-mediated lateral root organogenesis by regulating the endocytic recycling of the auxin carrier PIN1, but since then, few works have addressed this issue. Modulation of the cellular cytoskeleton and trafficking could potentially be a mechanism executing responses downstream of CK signaling. We recently reported that CK affects the trafficking of the pattern recognition receptor LeEIX2, influencing the resultant defense output. We have also recently found that CK affects cellular trafficking and the actin cytoskeleton in fungi. In this work, we take an in-depth look at the effects of CK on cellular trafficking and on the actin cytoskeleton in plant cells. We find that CK influences the actin cytoskeleton and endomembrane compartments, both in the context of defense signaling-where CK acts to amplify the signal-as well as in steady state. We show that CK affects the distribution of FLS2, increasing its presence in the plasma membrane. Furthermore, CK enhances the cellular response to flg22, and flg22 sensing activates the CK response. Our results are in agreement with what we previously reported for fungi, suggesting a fundamental role for CK in regulating cellular integrity and trafficking as a mechanism for controlling and executing CK-mediated processes.


Assuntos
Citoesqueleto de Actina/metabolismo , Arabidopsis/imunologia , Citocininas/farmacologia , Citoesqueleto de Actina/efeitos dos fármacos , Arabidopsis/efeitos dos fármacos , Arabidopsis/genética , Transporte Biológico/efeitos dos fármacos , Endossomos/efeitos dos fármacos , Endossomos/metabolismo , Flagelina/farmacologia , Modelos Biológicos , Epiderme Vegetal/citologia , Imunidade Vegetal/efeitos dos fármacos , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas , Receptores de Reconhecimento de Padrão/metabolismo , Tabaco/metabolismo
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