Nocardiosis is an uncommon infectious disease that bears certain similarities to tuberculosis, with a continuous increase in its incidence and a poor prognosis. In traditional Chinese medicine, the ...leaves of Cajanus cajan (L.) Millsp. are employed to treat wounds, malaria, coughs, and abdominal pain.
In this study, we investigated the effects and mechanisms of longistylin A (LGA), a natural stilbene isolated from C. cajan, as a potential antibiotic against nocardiosis.
LGA was isolated from the leaves of C. cajan and assessed using a minimum bactericidal concentration (MBC) determination against Nocardia seriolae. Multi-omics analysis encompassing genes, proteins, and metabolites was conducted to investigate the impact of LGA treatment on N. seriolae. Additionally, quantitative analysis of 40 cytokinins in N. seriolae mycelium was performed to assess the specific effects of LGA treatment on cytokinin levels. Cryo-scanning electron microscopy was utilized to examine morphological changes induced by LGA treatment, particularly in the presence of exogenous trans-zeatin-O-glucoside (tZOG). The therapeutic effect of LGA was investigated by feeding N. seriolae-infected largemouth bass.
LGA exhibited significant efficacy against N. seriolae, with MBC value of 2.56 μg/mL. Multi-omics analysis revealed that LGA disrupted glycerophospholipid metabolism and hormone biosynthesis by notably reducing the expression of glycerol-3-phosphate dehydrogenase and calmodulin-like protein. Treatment with LGA markedly disrupted 12 distinct cytokinins in N. seriolae mycelium. Additionally, the addition of exogenous tZOG counteracted the inhibitory effects of LGA on filamentous growth, resulting in mycelial elongation and branching. Furthermore, LGA treatment improved the survival rate of largemouth bass infected with N. seriolae.
We found for the first time that LGA from C. cajan exhibited significant efficacy against N. seriolae by interfering with glycerophospholipid metabolism and cytokinin biosynthesis.
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•CJE and LGA displayed a noteworthy anti-N. seriolae efficacy.•LGA interfered glycerophospholipid metabolism and hormone biosynthesis.•LGA notably reduced the expression of glycerol-3-phosphate dehydrogenase and calmodulin-like protein.•LGA disrupted 12 cytokinins in N. seriolae， tZOG counteracted LGA-elicited inhibition on the filamentous growth.•LGA enhanced the survival rate of largemouth bass infected with N. seriolae.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ
Cytokinins are phytohormones that induce cytokinesis and are essential for diverse developmental and physiological processes in plants. Cytokinins of the trans -zeatin type are mainly synthesized in ...root vasculature and transported to the shoot, where they regulate shoot growth. However, the mechanism of long-distance transport of cytokinin was hitherto unknown. Here, we report that the Arabidopsis ATP-binding cassette (ABC) transporter subfamily G14 (AtABCG14) is mainly expressed in roots and plays a major role in delivering cytokinins to the shoot. Loss of AtABCG14 expression resulted in severe shoot growth retardation, which was rescued by exogenous trans -zeatin application. Cytokinin content was decreased in the shoots of atabcg14 plants and increased in the roots, with consistent changes in the expression of cytokinin-responsive genes. Grafting of atabcg14 scions onto wild-type rootstocks restored shoot growth, whereas wild-type scions grafted onto atabcg14 rootstocks exhibited shoot growth retardation similar to that of atabcg14 . Cytokinin concentrations in the xylem are reduced by ∼90% in the atabcg14 mutant. These results indicate that AtABCG14 is crucial for the translocation of cytokinin to the shoot. Our results provide molecular evidence for the long-distance transport of cytokinin and show that this transport is necessary for normal shoot development.
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Plant activators such as benzothiadiazole (BTH) protect plants against diseases by priming the salicylic acid (SA) signaling pathway. In rice, the transcription factor WRKY45 plays a central role in ...this process. To investigate the mechanism involved in defense-priming by BTH and the role of WRKY45 in this process, we analyzed the transcripts of biosynthetic genes for diterpenoid phytoalexins (DPs) during the rice–Magnaporthe oryzae interaction. The DP biosynthetic genes were barely upregulated in BTH-treated rice plants, but were induced rapidly after M. oryzae infection in a WRKY45-dependent manner. These results indicate that the DP biosynthetic genes were primed by BTH through WRKY45. Rapid induction of the DP biosynthetic genes was also observed after M. oryzae infection to WRKY45-overexpressing (WRKY45-ox) plants. The changes in gene transcription resulted in accumulation of DPs in WRKY45-ox and BTH-pretreated rice after M. oryzae infection. Previously, we reported that cytokinins (CKs), especially isopentenyladenines, accumulated in M. oryzae-infected rice. Here, we show that DP biosynthetic genes are regulated by the SA/CK synergism in a WRKY45-dependent manner. Together, we propose that CK plays a role in mediating the signal of M. oryzae infection to trigger the induction of DP biosynthetic genes in BTH-primed plants.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The Stevia rebaudiana Germplasm Bank at the University of Cordoba, Colombia, plays a pivotal role in conserving and efficiently utilizing the genetic variability of this species. Despite safeguarding ...promising genotypes with valuable traits, such as late flowering or a significant diterpenoid glycoside content, there is a need for an efficient mass propagation protocol for elite genotypes. This study aims to develop efficient in vitro micropropagation protocols for three elite S. rebaudiana genotypes (L020, L102, and Morita II). The methods employed various combinations of cytokinins and auxins following organogenesis protocols. The results showed that optimal shoot multiplication (17.3 shoots per explant) for L020 was achieved when cultures were grown on a basal medium MS supplemented with 1 μM 6-benzylaminopurine (BAP). For L102, optimal shoot multiplication (18.5 shoots per explant) was achieved in MS supplemented with 1 μM BAP and 0.5 μM naphthalene acetic acid (NAA), while for Morita II, the best treatment was an MS supplemented with 2 μM BAP and 0.5 μM NAA, producing 16.4 shoots per explant. This study successfully achieved micropropagation for promising S. rebaudiana genotypes, highlighting the significant impact of genotype on tissue culture, particularly in shoot multiplication. Developing a successful micropropagation system is crucial for the conservation and improvement of S. rebaudiana, with significant implications for its future use and performance.
Members of the TaCKX gene family (GFM) encode oxidase/dehydrogenase cytokinin degrading enzymes (CKX), which play an important role in the homeostasis of phytohormones, affecting wheat development ...and productivity. Therefore, the objective of this investigation was to test how the expression patterns of the yield-related TaCKX genes and TaNAC2-5A (NAC2) measured in 7 days after pollination (DAP) spikes and the seedling roots of parents are inherited to apply this knowledge in the breeding process. The expression patterns of these genes were compared between parents and their F2 progeny in crosses of one mother with different paterns of awnless cultivars and reciprocal crosses of awned and awnless lines. We showed that most of the genes tested in the 7 DAP spikes and seedling roots of the Fsub.2 progeny showed paternal expression patterns in crosses of awnless cultivars as well as reciprocal crosses of awned and awnless lines. Consequently, the values of grain yield in the Fsub.2 progeny were similar to the pater; however, the values of seedling root mass were similar to the mother or both parents. The correlation analysis of TaCKX GFMs and NAC2 in spikes and spikes per seedling roots reveals that the genes correlate with each other specifically with the pater and the Fsub.2 progeny or the mother and the Fsub.2 progeny, which shape phenotypic traits. The numbers of spikes and semi-empty spikes are mainly correlated with the specific coexpression of the TaCKX and NAC2 genes expressed in spikes or spikes per roots of the pater and Fsub.2 progeny. Variable regression analysis of grain yield and root mass with TaCKX GFMs and NAC2 expressed in the tested tissues of five crosses revealed a significant dependency of these parameters on the mother and Fsub.2 and/or the pater and Fsub.2 progeny. We showed that the inheritance of yield-related traits depends on the specific cooperative expression of some TaCKX GFMs, in some crosses coupled with NAC2, and is strongly dependent on the genotypes used for the crosses. Indications for parental selection in the breeding of high-yielding lines are discussed.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
The phenomenon of plant root tips sensing moisture gradient in soil and growing towards higher water potential is designated as root hydrotropism, which is critical for plants to survive when water ...is a limited factor. Molecular mechanisms regulating such a fundamental process, however, are largely unknown. Here we report our identification that cytokinins are key signaling molecules directing root growth orientation in a hydrostimulation (moisture gradient) condition. Lower water potential side of the root tip shows more cytokinin response relative to the higher water potential side. Consequently, two cytokinin downstream type-A response regulators, ARR16 and ARR17, were found to be up-regulated at the lower water potential side, causing increased cell division in the meristem zone, which allows the root to bend towards higher water potential side. Genetic analyses indicated that various cytokinin biosynthesis and signaling mutants, including the arr16 arr17 double mutant, are significantly less responsive to hydrostimulation. Consistently, treatments with chemical inhibitors interfering with either cytokinin biosynthesis or cell division completely abolished root hydrotropic response. Asymmetrically induced expression of ARR16 or ARR17 effectively led to root bending in both wild-type and miz1, a previously known hydrotropism-defective mutant. These data demonstrate that asymmetric cytokinin distribution is a primary determinant governing root hydrotropism.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Plant beneficial microbes mediate biocontrol of diseases by interfering with pathogens or via strengthening the host. Although phytohormones, including cytokinins, are known to regulate plant ...development and physiology as well as plant immunity, their production by microorganisms has not been considered as a biocontrol mechanism. Here we identify the ability of Pseudomonas fluorescens G20-18 to efficiently control P. syringae infection in Arabidopsis, allowing maintenance of tissue integrity and ultimately biomass yield. Microbial cytokinin production was identified as a key determinant for this biocontrol effect on the hemibiotrophic bacterial pathogen. While cytokinin-deficient loss-of-function mutants of G20-18 exhibit impaired biocontrol, functional complementation with cytokinin biosynthetic genes restores cytokinin-mediated biocontrol, which is correlated with differential cytokinin levels in planta. Arabidopsis mutant analyses revealed the necessity of functional plant cytokinin perception and salicylic acid-dependent defence signalling for this biocontrol mechanism. These results demonstrate microbial cytokinin production as a novel microbe-based, hormone-mediated concept of biocontrol. This mechanism provides a basis to potentially develop novel, integrated plant protection strategies combining promotion of growth, a favourable physiological status and activation of fine-tuned direct defence and abiotic stress resilience.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Essential oils (EOs) are of commercial importance for medicine, food, cosmetics, the perfume industry, and agriculture. In plants, EOs, like the wax cover, serve as protection against abiotic ...stresses, such as high temperatures and water deficiency. The use of spraying with exogenous hormones of aromatic plants affects the accumulation and composition of volatile compounds, as well as tolerance to abiotic stress. As a result of cytokinin treatment with 6-BAP (6-benzylaminopurine) (200 mg Lsup.−l) of Anetum graveolens L. “Uzory” and “Rusich” varieties, several responses to its action were revealed: a change in the division of leaf blades, inhibition of flowering, an increase in the content of EO and its main components α-phellandrene and p-cymene in leaves, and limonene in umbels and fruits. It was revealed that the increased accumulation of EO in dill leaves was longer with sufficient moisture. In contrast, under conditions of heat and water deficiency, the effect of 6-BAP treatment on accumulations of the EO in leaves was short-lived and did not appear on umbels and fruits. The study of the cytokinin effect on a fine structure of a wax cover on the adaxial side of leaves by scanning electron microscopy revealed a change in its elements (from amorphous layers with scales to thin tubules), which probably increased the sensitivity of leaves to water deficiency and, consequently, led to a decrease in the biosynthetic activity of leaf tissue. Thus, 6-BAP had an impact on the adaptive properties of dill plants, prolonging the “youth” of vegetative organs and the ability to EO biosynthesis under conditions of sufficient moisture.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Although a substantial proportion of plant biomass originates from the activity of vascular cambium, the molecular basis of radial plant growth is still largely unknown. To address whether cytokinins ...are required for cambial activity, we studied cytokinin signaling across the cambial zones of 2 tree species, poplar (Populus trichocarpa) and birch (Betula pendula). We observed an expression peak for genes encoding cytokinin receptors in the dividing cambial cells. We reduced cytokinin levels endogenously by engineering transgenic poplar trees (P. tremula x tremuloides) to express a cytokinin catabolic gene, Arabidopsis CYTOKININ OXIDASE 2, under the promoter of a birch CYTOKININ RECEPTOR 1 gene. Transgenic trees showed reduced concentration of a biologically active cytokinin, correlating with impaired cytokinin responsiveness. In these trees, both apical and radial growth was compromised. However, radial growth was more affected, as illustrated by a thinner stem diameter than in WT at same height. To dissect radial from apical growth inhibition, we performed a reciprocal grafting experiment. WT scion outgrew the diameter of transgenic stock, implicating cytokinin activity as a direct determinant of radial growth. The reduced radial growth correlated with a reduced number of cambial cell layers. Moreover, expression of a cytokinin primary response gene was dramatically reduced in the thin-stemmed transgenic trees. Thus, a reduced level of cytokinin signaling is the primary basis for the impaired cambial growth observed. Together, our results show that cytokinins are major hormonal regulators required for cambial development.
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Key message
Cytokinins are a class of phytohormone that participate in the regulation of the plant growth, development, and stress response. In this review, the potential regulating mechanism during ...plant growth and stress response are discussed.
Cytokinins are a class of phytohormone that participate in the regulation of plant growth, physiological activities, and yield. Cytokinins also play a key role in response to abiotic stresses, such as drought, salt and high or low temperature. Through the signal transduction pathway, cytokinins interact with various transcription factors via a series of phosphorylation cascades to regulate cytokinin-target gene expression. In this review, we systematically summarize the biosynthesis and metabolism of cytokinins, cytokinin signaling, and associated gene regulation, and highlight the function of cytokinins during plant development and resistance to abiotic stress. We also focus on the importance of crosstalk between cytokinins and other classes of phytohormones, including auxin, ethylene, strigolactone, and gibberellin. Our aim is to provide a comprehensive overview of recent findings on the mechanisms by which cytokinins act as central regulators of plant development and stress reactions, and highlight topics for future research.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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