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Phytohormones
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Phytohormones

A special issue of Biomolecules (ISSN 2218-273X). This special issue belongs to the section "Natural and Bio-inspired Molecules".

Deadline for manuscript submissions: closed (31 December 2019) | Viewed by 97188

Special Issue Editor

Prof. Dr. Guzel Kudoyarova

E-Mail Website
Guest Editor
Laboratory of Plant Physiology, Ufa Institute of Biology of the Russian Academy of Sciences, Ufa 450054, Russia
Interests: plant productivity; phytohormones; plant growth promoting bacteria; bacterial metabolites; plant-microorganism interaction
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The hormonal system plays a decisive role in the control of plant growth and development. Alongside with classical plant hormones (auxins, cytokinins, gibberellins, abscisic acid) hormonal function is now attributed to jasmonates, salicylic acid, and brassinosteroids. Plant hormones are capable of influencing vital processes, including plant growth and development, adaptation to environment, and resistance to biotic and abiotic stresses and productivity. In accordance, plant hormones are attractive tools for biotechnology aimed at improving plant performance in accordance with human needs. Thus, synthesis of plant hormones by rhizosphere microorganisms is the base for their capacity to promote plant growth as well as for application of their preparations in crop production. Still, the success of the use of plant hormones depends on the knowledge of the mechanisms of their action. Advances in the study of plants hormones include discovery of their receptors and cascades of hormonal signal transduction, identification of their target genes and those controlling hormonal metabolism and signaling, revealing cross-talk between hormones and their interaction with calcium, reactive oxygen species and nitrogen oxide signaling.

We invite investigators to contribute high-quality original research and review articles focused on the implication of plant hormones in plant growth and development, their adaptation to the environment and resistance to abiotic and biotic stresses (molecular, cellular, and whole plant aspects of the problems), cross-talk between plant hormones and their interaction with other signaling systems, and the importance of hormones for the plant growth promotion by soil microorganisms.

Dr. Guzel Kudoyarova
Guest Editor

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Biomolecules is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • auxins
  • cytokinins
  • gibberellins
  • abscisic acid
  • ethylene
  • jasmonates
  • salicylic acid
  • brassinosteroids
  • hormonal signaling
  • metabolism of hormones
  • hormonal target genes
  • hormonal control of plant growth and development
  • resistance
  • productivity

Published Papers (21 papers)

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17 pages, 2468 KiB  
Article
MYB Superfamily in Brassica napus: Evidence for Hormone-Mediated Expression Profiles, Large Expansion, and Functions in Root Hair Development
by Pengfeng Li, Jing Wen, Ping Chen, Pengcheng Guo, Yunzhuo Ke, Mangmang Wang, Mingming Liu, Lam-Son Phan Tran, Jiana Li and Hai Du
Biomolecules 2020, 10(6), 875; https://doi.org/10.3390/biom10060875 - 7 Jun 2020
Cited by 19 | Viewed by 2976
Abstract
MYB proteins are involved in diverse important biological processes in plants. Herein, we obtained the MYB superfamily from the allotetraploid Brassica napus, which contains 227 MYB-related (BnMYBR/Bn1R-MYB), 429 R2R3-MYB (Bn2R-MYB), 22 R1R2R3-MYB (Bn3R-MYB), [...] Read more.
MYB proteins are involved in diverse important biological processes in plants. Herein, we obtained the MYB superfamily from the allotetraploid Brassica napus, which contains 227 MYB-related (BnMYBR/Bn1R-MYB), 429 R2R3-MYB (Bn2R-MYB), 22 R1R2R3-MYB (Bn3R-MYB), and two R1R2R2R1/2-MYB (Bn4R-MYB) genes. Phylogenetic analysis classified the Bn2R-MYBs into 43 subfamilies, and the BnMYBRs into five subfamilies. Sequence characteristics and exon/intron structures within each subfamily of the Bn2R-MYBs and BnMYBRs were highly conserved. The whole superfamily was unevenly distributed on 19 chromosomes and underwent unbalanced expansion in B. napus. Allopolyploidy between B. oleracea and B. rapa mainly contributed to the expansion in their descendent B. napus, in which B. rapa-derived genes were more retained. Comparative phylogenetic analysis of 2R-MYB proteins from nine Brassicaceae and seven non-Brassicaceae species identified five Brassicaceae-specific subfamilies and five subfamilies that are lacking from the examined Brassicaceae species, which provided an example for the adaptive evolution of the 2R-MYB gene family alongside angiosperm diversification. Ectopic expression of four Bn2R-MYBs under the control of the viral CaMV35S and/or native promoters could rescue the lesser root hair phenotype of the Arabidopsis thaliana wer mutant plants, proving the conserved negative roles of the 2R-MYBs of the S15 subfamily in root hair development. RNA-sequencing data revealed that the Bn2R-MYBs and BnMYBRs had diverse transcript profiles in roots in response to the treatments with various hormones. Our findings provide valuable information for further functional characterizations of B. napus MYB genes. Full article
(This article belongs to the Special Issue Phytohormones)
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17 pages, 2597 KiB  
Article
Negative Roles of Strigolactone-Related SMXL6, 7 and 8 Proteins in Drought Resistance in Arabidopsis
by Weiqiang Li, Kien Huu Nguyen, Cuong Duy Tran, Yasuko Watanabe, Chunjie Tian, Xiaojian Yin, Kun Li, Yong Yang, Jinggong Guo, Yuchen Miao, Shinjiro Yamaguchi and Lam-Son Phan Tran
Biomolecules 2020, 10(4), 607; https://doi.org/10.3390/biom10040607 - 14 Apr 2020
Cited by 43 | Viewed by 3940
Abstract
Previous investigations have shown that the SUPPRESSORS OF MAX2 1-LIKE6, 7 and 8 (SMXL6, 7 and 8) proteins redundantly repress strigolactone (SL) signaling in plant growth and development. Recently, a growing body of evidence indicated that SLs positively regulate plant drought resistance through [...] Read more.
Previous investigations have shown that the SUPPRESSORS OF MAX2 1-LIKE6, 7 and 8 (SMXL6, 7 and 8) proteins redundantly repress strigolactone (SL) signaling in plant growth and development. Recently, a growing body of evidence indicated that SLs positively regulate plant drought resistance through functional analyses of genes involved in SL biosynthesis and positive regulation of SL signaling. However, the functions of the SL-signaling negative regulators SMXL6, 7 and 8 in drought resistance and the associated mechanisms remain elusive. To reveal the functions of these SMXL proteins, we analyzed the drought-resistant phenotype of the triple smxl6,7,8 mutant plants and studied several drought resistance-related traits. Our results showed that the smxl6,7,8 mutant plants were more resistant to drought than wild-type plants. Physiological investigations indicated that the smxl6,7,8 mutant plants exhibited higher leaf surface temperature, reduced cuticle permeability, as well as decreases in drought-induced water loss and cell membrane damage in comparison with wild-type plants. Additionally, smxl6,7,8 mutant plants displayed an increase in anthocyanin biosynthesis during drought, enhanced detoxification capacity and increased sensitivity to abscisic acid in cotyledon opening and growth inhibition assays. A good correlation between the expression levels of some relevant genes and the examined physiological and biochemical traits was observed. Our findings together indicate that the SMXL6, 7 and 8 act as negative regulators of drought resistance, and that disruption of these SMXL genes in crops may provide a novel way to improve their drought resistance. Full article
(This article belongs to the Special Issue Phytohormones)
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15 pages, 5134 KiB  
Article
Indoleacetic Acid Levels in Wheat and Rice Seedlings under Oxygen Deficiency and Subsequent Reoxygenation
by Vladislav V. Yemelyanov, Victor V. Lastochkin, Tamara V. Chirkova, Sylvia M. Lindberg and Maria F. Shishova
Biomolecules 2020, 10(2), 276; https://doi.org/10.3390/biom10020276 - 11 Feb 2020
Cited by 17 | Viewed by 3136
Abstract
The lack of oxygen and post-anoxic reactions cause significant alterations of plant growth and metabolism. Plant hormones are active participants in these alterations. This study focuses on auxin–a phytohormone with a wide spectrum of effects on plant growth and stress tolerance. The indoleacetic [...] Read more.
The lack of oxygen and post-anoxic reactions cause significant alterations of plant growth and metabolism. Plant hormones are active participants in these alterations. This study focuses on auxin–a phytohormone with a wide spectrum of effects on plant growth and stress tolerance. The indoleacetic acid (IAA) content in plants was measured by ELISA. The obtained data revealed anoxia-induced accumulation of IAA in wheat and rice seedlings related to their tolerance of oxygen deprivation. The highest IAA accumulation was detected in rice roots. Subsequent reoxygenation was accompanied with a fast auxin reduction to the control level. A major difference was reported for shoots: wheat seedlings contained less than one-third of normoxic level of auxin during post-anoxia, while IAA level in rice seedlings rapidly recovered to normoxic level. It is likely that the mechanisms of auxin dynamics resulted from oxygen-induced shift in auxin degradation and transport. Exogenous IAA treatment enhanced plant survival under anoxia by decreased electrolyte leakage, production of hydrogen peroxide and lipid peroxidation. The positive effect of external IAA application coincided with improvement of tolerance to oxygen deprivation in the 35S:iaaM × 35S:iaaH lines of transgene tobacco due to its IAA overproduction. Full article
(This article belongs to the Special Issue Phytohormones)
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15 pages, 1650 KiB  
Article
The Stimulatory Effect of Purine-Type Cytokinins on Proliferation and Polyphenolic Compound Accumulation in Shoot Culture of Salvia viridis
by Izabela Grzegorczyk-Karolak, Katarzyna Hnatuszko-Konka, Mariola Zarzycka and Łukasz Kuźma
Biomolecules 2020, 10(2), 178; https://doi.org/10.3390/biom10020178 - 24 Jan 2020
Cited by 13 | Viewed by 2517
Abstract
The present study demonstrates hormonal control of Salvia viridis growth and development using four different purine-type cytokinins at different concentrations. The addition of cytokinins significantly increased biomass of cultures, proliferation rate, and, interestingly, secondary metabolite production. The best response in terms of multiplication [...] Read more.
The present study demonstrates hormonal control of Salvia viridis growth and development using four different purine-type cytokinins at different concentrations. The addition of cytokinins significantly increased biomass of cultures, proliferation rate, and, interestingly, secondary metabolite production. The best response in terms of multiplication ratio was recorded on Murashige and Skoog medium supplemented with 0.5 mg/L BPA (N-benzylotetrahydropyranyl adenine), while the greatest biomass accumulation was achieved when supplemented with 1 mg/L m-T (meta-topoline). Quantitative UPLC-DAD analysis of the hydromethanolic extract from S. viridis culture revealed the presence of 12 polyphenols: seven phenolic acids and five phenylethanoids. The highest total content of polyphenolic compounds was found in shoots cultivated on medium with 2 mg/L BPA (18.66 mg/g DW): almost twice that of control shoots. The medium was also the most optimal for the biosynthesis of rosmarinic acid, the predominant phenolic acid. However, the greater phenylethanoid accumulation was stimulated by 1 mg/L m-T: the metabolite content was above three times higher than that found in shoots grown on the control medium (8.03 mg/g DW vs. 2.37 mg/g DW). Hence, it was demonstrated that phytohormones are capable of influencing not only vital physiological processes, but therapeutic potential of plants as well. Therefore, the cytokinin-based sage cultures may be also considered as the alternative sources of bioactive compounds. Full article
(This article belongs to the Special Issue Phytohormones)
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21 pages, 5203 KiB  
Article
Combined Kinetin and Spermidine Treatments Ameliorate Growth and Photosynthetic Inhibition in Vigna angularis by Up-Regulating Antioxidant and Nitrogen Metabolism under Cadmium Stress
by Mohammad Abass Ahanger, Usman Aziz, Abdulaziz Alsahli, Mohammed Nasser Alyemeni and Parvaiz Ahmad
Biomolecules 2020, 10(1), 147; https://doi.org/10.3390/biom10010147 - 16 Jan 2020
Cited by 80 | Viewed by 4043
Abstract
Pot experiments were conducted to investigate the probable beneficial role of the individual as well as combined application of kinetin (50 μM Kn) and spermidine (200 μM Spd) on Vigna angularis under cadmium (Cd) stress. Cd treatment reduced growth by declining the content [...] Read more.
Pot experiments were conducted to investigate the probable beneficial role of the individual as well as combined application of kinetin (50 μM Kn) and spermidine (200 μM Spd) on Vigna angularis under cadmium (Cd) stress. Cd treatment reduced growth by declining the content of chlorophylls and carotenoids, photosynthesis, and gas exchange parameters. Exogenously, Kn and Spd application enhanced the photosynthetic parameters and up-regulated the antioxidant system by improving the activities of antioxidant enzymes and the content of non-enzymatic components. In addition, the application of Kn and Spd resulted in significant improvement in the content of sugars, proline, and glycine betaine, ameliorating the decline in relative water content. Oxidative stress parameters including hydrogen peroxide, superoxide, lipid peroxidation, lipoxygenase activity, and electrolyte leakage increased due to Cd stress; however, the application of Kn and Spd imparted a significant decline in all these parameters. Further, reduced Cd uptake was also observed due to Kn and Spd application. Total phenols and flavonoids also increased due to Kn and Spd treatments under normal as well as Cd stress conditions, which may have further helped with the elimination of reactive oxygen species. Reduction in the activity of nitrate reductase and the content of nitrogen was ameliorated due to the exogenous application of Kn and Spd. Therefore, the exogenous application of Kn and Spd benefited Vigna angularis counteracting the damaging effects of Cd stress by up-regulating the tolerance mechanisms, including antioxidant and osmolyte metabolism. Full article
(This article belongs to the Special Issue Phytohormones)
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16 pages, 2695 KiB  
Article
Combining Physiological and Metabolomic Analysis to Unravel the Regulations of Coronatine Alleviating Water Stress in Tobacco (Nicotiana tabacum L.)
by Jiayang Xu, Yuyi Zhou, Zicheng Xu, Zheng Chen and Liusheng Duan
Biomolecules 2020, 10(1), 99; https://doi.org/10.3390/biom10010099 - 7 Jan 2020
Cited by 25 | Viewed by 3463
Abstract
Drought is a major abiotic stress that restricts plants growth, development, and yield. Coronatine (COR), a mimic of JA-Ile, functions in plant tolerance to multiple stresses. In our study, we examined the effects of COR in tobacco under polyethylene glycol (PEG) stress. COR [...] Read more.
Drought is a major abiotic stress that restricts plants growth, development, and yield. Coronatine (COR), a mimic of JA-Ile, functions in plant tolerance to multiple stresses. In our study, we examined the effects of COR in tobacco under polyethylene glycol (PEG) stress. COR treatment improved plant growth under stress as measured by fresh weight (FW) and dry weight (DW). The enzyme activity assay indicated that, under osmotic stress conditions, the activities of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and glutathione reductase (GR) were enhanced by COR treatment. Histochemical analyses via nitrotetrazolium blue chloride (NBT) and 3,3′-diaminobenzidine (DAB) staining showed that COR reduced reactive oxygen species (ROS) accumulation during osmotic stress. Metabolite profiles revealed that COR triggered significant metabolic changes in tobacco leaves under osmotic stress, and many essential metabolites, such as sugar and sugar derivatives, organic acids, and nitrogen-containing compounds, which might play active roles in osmotic-stressed tobacco plants, were markedly accumulated in the COR-treated tobacco. The work presented here provides a comprehensive understanding of the COR-mediated physiological, biochemical, and metabolic adjustments that minimize the adverse impact of osmotic stress on tobacco. Full article
(This article belongs to the Special Issue Phytohormones)
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18 pages, 2798 KiB  
Article
Seed Priming with Jasmonic Acid Counteracts Root Knot Nematode Infection in Tomato by Modulating the Activity and Expression of Antioxidative Enzymes
by Shagun Bali, Parminder Kaur, Vijay Lakshmi Jamwal, Sumit G. Gandhi, Anket Sharma, Puja Ohri, Renu Bhardwaj, Mohammad Ajmal Ali and Parvaiz Ahmad
Biomolecules 2020, 10(1), 98; https://doi.org/10.3390/biom10010098 - 7 Jan 2020
Cited by 28 | Viewed by 3487
Abstract
The environmental stress, biotic as well as abiotic, is the main cause of decreased growth and crop production. One of the stress-causing agents in plants are parasitic nematodes responsible for crop loss. Jasmonic acid (JA) is recognized as one of signaling molecules in [...] Read more.
The environmental stress, biotic as well as abiotic, is the main cause of decreased growth and crop production. One of the stress-causing agents in plants are parasitic nematodes responsible for crop loss. Jasmonic acid (JA) is recognized as one of signaling molecules in defense-related responses in plants, however, its role under nematode infestation is unclear. Therefore, the present study was planned to traverse the role of JA in boosting the activities of antioxidative enzymes in tomato seedlings during nematode inoculation. Application of JA declined oxidative damage by decreasing O2•− content, nuclear and membrane damage under nematode stress. JA treatment elevated the activities of SOD, POD, CAT, APOX, DHAR, GPOX, GR, and PPO in nematode-infested seedlings. Seed soaking treatment of JA upregulated the expression of SOD, POD, CAT, and GPOX under nematode stress. Various amino acids were found in tomato seedlings and higher content of aspartic acid, histidine, asparagine, glutamine, glutamic acid, glycine, threonine, lysine, arginine, B-alanine, GABA, phenylalanine, proline, and ornithine was observed in seeds soaked with JA (100 nM) treatment during nematode inoculation. The results suggest an indispensable role of JA in basal defense response in plants during nematode stress. Full article
(This article belongs to the Special Issue Phytohormones)
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14 pages, 1609 KiB  
Article
Distinct Peculiarities of In Planta Synthesis of Isoprenoid and Aromatic Cytokinins
by Vladimir E. Oslovsky, Ekaterina M. Savelieva, Mikhail S. Drenichev, Georgy A. Romanov and Sergey N. Mikhailov
Biomolecules 2020, 10(1), 86; https://doi.org/10.3390/biom10010086 - 5 Jan 2020
Cited by 4 | Viewed by 3207
Abstract
The biosynthesis of aromatic cytokinins in planta, unlike isoprenoid cytokinins, is still unknown. To compare the final steps of biosynthesis pathways of aromatic and isoprenoid cytokinins, we synthesized a series of nucleoside derivatives of natural cytokinins starting from acyl-protected ribofuranosyl-, 2′-deoxyribofuranosyl- and [...] Read more.
The biosynthesis of aromatic cytokinins in planta, unlike isoprenoid cytokinins, is still unknown. To compare the final steps of biosynthesis pathways of aromatic and isoprenoid cytokinins, we synthesized a series of nucleoside derivatives of natural cytokinins starting from acyl-protected ribofuranosyl-, 2′-deoxyribofuranosyl- and 5′-deoxyribofuranosyladenine derivatives using stereoselective alkylation with further deblocking. Their cytokinin activity was determined in two bioassays based on model plants Arabidopsis thaliana and Amaranthus caudatus. Unlike active cytokinins-bases, cytokinin nucleosides lack the hormonal activity until the ribose moiety is removed. According to our experiments, ribo-, 2′-deoxyribo- and 5′-deoxyribo-derivatives of isoprenoid cytokinin N6-isopentenyladenine turned in planta into active cytokinins with clear hormonal activity. As for aromatic cytokinins, both 2′-deoxyribo- and 5′-deoxyribo-derivatives did not exhibit analogous activity in Arabidopsis. The 5′-deoxyribo-derivatives cannot be phosphorylated enzymatically in vivo; therefore, they cannot be “activated” by the direct LOG-mediated cleavage, largely occurring with cytokinin ribonucleotides in plant cells. The contrasting effects exerted by deoxyribonucleosides of isoprenoid (true hormonal activity) and aromatic (almost no activity) cytokinins indicates a significant difference in the biosynthesis of these compounds. Full article
(This article belongs to the Special Issue Phytohormones)
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16 pages, 4440 KiB  
Article
Influence of Exogenous Salicylic Acid and Nitric Oxide on Growth, Photosynthesis, and Ascorbate-Glutathione Cycle in Salt Stressed Vigna angularis
by Mohammad Abass Ahanger, Usman Aziz, Abdulaziz Abdullah Alsahli, Mohammed Nasser Alyemeni and Parvaiz Ahmad
Biomolecules 2020, 10(1), 42; https://doi.org/10.3390/biom10010042 - 26 Dec 2019
Cited by 219 | Viewed by 6480
Abstract
The present study was carried out to investigate the beneficial role of exogenous application of salicylic acid (1 mM SA) and nitric oxide (100 μM NO) in preventing the oxidative damage in Vigna angularis triggered by salinity stress. Salinity (100 mM NaCl) stress [...] Read more.
The present study was carried out to investigate the beneficial role of exogenous application of salicylic acid (1 mM SA) and nitric oxide (100 μM NO) in preventing the oxidative damage in Vigna angularis triggered by salinity stress. Salinity (100 mM NaCl) stress reduced growth, biomass accumulation, chlorophyll synthesis, photosynthesis, gas exchange parameters, and photochemical efficiency (Fv/Fm) significantly. Exogenous application of SA and NO was affective in enhancing these growth and photosynthetic parameters. Salinity stress reduced relative water content over control. Further, the application of SA and NO enhanced the synthesis of proline, glycine betaine, and sugars as compared to the control as well as NaCl treated plants contributing to the maintenance of tissue water content. Exogenous application of SA and NO resulted in up-regulation of the antioxidant system. Activities of enzymatic antioxidants including superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), dehydroascorbate reductase (DHAR), and glutathione reductase (GR), as well as the content of non-enzymatic components, were more in SA + NO treated seedlings as compared to control and salinity stressed counterparts resulting in significant alleviation of the NaCl mediated oxidative damage. Content of nitrogen, potassium, and calcium increased due to SA and NO under normal conditions and NaCl stress conditions while as Na and Cl content reduced significantly. Full article
(This article belongs to the Special Issue Phytohormones)
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12 pages, 4949 KiB  
Article
Role of Pea LTPs and Abscisic Acid in Salt-Stressed Roots
by Guzel R. Akhiyarova, Ekaterina I. Finkina, Tatiana V. Ovchinnikova, Dmitry S. Veselov and Guzel R. Kudoyarova
Biomolecules 2020, 10(1), 15; https://doi.org/10.3390/biom10010015 - 20 Dec 2019
Cited by 11 | Viewed by 2893
Abstract
Lipid transfer proteins (LTPs) are a class of small, cationic proteins that bind and transfer lipids and play an important role in plant defense. However, their precise biological role in plants under adverse conditions including salinity and possible regulation by stress hormone abscisic [...] Read more.
Lipid transfer proteins (LTPs) are a class of small, cationic proteins that bind and transfer lipids and play an important role in plant defense. However, their precise biological role in plants under adverse conditions including salinity and possible regulation by stress hormone abscisic acid (ABA) remains unknown. In this work, we studied the localization of LTPs and ABA in the roots of pea plants using specific antibodies. Presence of LTPs was detected on the periphery of the cells mainly located in the phloem. Mild salt stress (50 mM NaCI) led to slowing plant growth and higher immunostaining for LTPs in the phloem. The deposition of suberin in Casparian bands located in the endoderma revealed with Sudan III was shown to be more intensive under salt stress and coincided with the increased LTP staining. All obtained data suggest possible functions of LTPs in pea roots. We assume that these proteins can participate in stress-induced pea root suberization or in transport of phloem lipid molecules. Salt stress increased ABA immunostaining in pea root cells but its localization was different from that of the LTPs. Thus, we failed to confirm the hypothesis regarding the direct influence of ABA on the level of LTPs in the salt-stressed root cells. Full article
(This article belongs to the Special Issue Phytohormones)
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13 pages, 2034 KiB  
Article
Brassinosteroids Induce Strong, Dose-Dependent Inhibition of Etiolated Pea Seedling Growth Correlated with Ethylene Production
by Petra Jiroutová, Jaromír Mikulík, Ondřej Novák, Miroslav Strnad and Jana Oklestkova
Biomolecules 2019, 9(12), 849; https://doi.org/10.3390/biom9120849 - 9 Dec 2019
Cited by 10 | Viewed by 3304
Abstract
We have recently discovered that brassinosteroids (BRs) can inhibit the growth of etiolated pea seedlings dose-dependently in a similar manner to the ‘triple response’ induced by ethylene. We demonstrate here that the growth inhibition of etiolated pea shoots strongly correlates with increases in [...] Read more.
We have recently discovered that brassinosteroids (BRs) can inhibit the growth of etiolated pea seedlings dose-dependently in a similar manner to the ‘triple response’ induced by ethylene. We demonstrate here that the growth inhibition of etiolated pea shoots strongly correlates with increases in ethylene production, which also responds dose-dependently to applied BRs. We assessed the biological activities of two natural BRs on pea seedlings, which are excellent material as they grow rapidly, and respond both linearly and uni-phasically to applied BRs. We then compared the BRs’ inhibitory effects on growth, and induction of ethylene and ACC (1-aminocyclopropane-1-carboxylic acid) production, to those of representatives of other phytohormone classes (cytokinins, auxins, and gibberellins). Auxin induced ca. 50-fold weaker responses in etiolated pea seedlings than brassinolide, and the other phytohormones induced much weaker (or opposite) responses. Following the optimization of conditions for determining ethylene production after BR treatment, we found a positive correlation between BR bioactivity and ethylene production. Finally, we optimized conditions for pea growth responses and developed a new, highly sensitive, and convenient bioassay for BR activity. Full article
(This article belongs to the Special Issue Phytohormones)
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15 pages, 2571 KiB  
Article
Ectopic Expression of Glycine max GmNAC109 Enhances Drought Tolerance and ABA Sensitivity in Arabidopsis
by Nguyen Cao Nguyen, Xuan Lan Thi Hoang, Quang Thien Nguyen, Ngo Xuan Binh, Yasuko Watanabe, Nguyen Phuong Thao and Lam-Son Phan Tran
Biomolecules 2019, 9(11), 714; https://doi.org/10.3390/biom9110714 - 7 Nov 2019
Cited by 14 | Viewed by 4104
Abstract
The NAC (NAM, ATAF1/2, CUC2) transcription factors are widely known for their various functions in plant development and stress tolerance. Previous studies have demonstrated that genetic engineering can be applied to enhance drought tolerance via overexpression/ectopic expression of NAC genes. In the present [...] Read more.
The NAC (NAM, ATAF1/2, CUC2) transcription factors are widely known for their various functions in plant development and stress tolerance. Previous studies have demonstrated that genetic engineering can be applied to enhance drought tolerance via overexpression/ectopic expression of NAC genes. In the present study, the dehydration- and drought-inducible GmNAC109 from Glycine max was ectopically expressed in Arabidopsis (GmNAC109-EX) plants to study its biological functions in mediating plant adaptation to water deficit conditions. Results revealed an improved drought tolerance in the transgenic plants, which displayed greater recovery rates by 20% to 54% than did the wild-type plants. In support of this finding, GmNAC109-EX plants exhibited lower water loss rates and decreased endogenous hydrogen peroxide production in leaf tissues under drought, as well as higher sensitivity to exogenous abscisic acid (ABA) treatment at germination and early seedling development stages. In addition, analyses of antioxidant enzymes indicated that GmNAC109-EX plants possessed stronger activities of superoxide dismutase and catalase under drought stress. These results together demonstrated that GmNAC109 acts as a positive transcriptional regulator in the ABA-signaling pathway, enabling plants to cope with adverse water deficit conditions. Full article
(This article belongs to the Special Issue Phytohormones)
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21 pages, 3812 KiB  
Article
24-Epibrassinolide (EBR) Confers Tolerance against NaCl Stress in Soybean Plants by Up-Regulating Antioxidant System, Ascorbate-Glutathione Cycle, and Glyoxalase System
by Pravej Alam, Thamer H. Albalawi, Fahad H. Altalayan, Md Afroz Bakht, Mohammad Abass Ahanger, Vaseem Raja, Muhammad Ashraf and Parvaiz Ahmad
Biomolecules 2019, 9(11), 640; https://doi.org/10.3390/biom9110640 - 23 Oct 2019
Cited by 125 | Viewed by 7054
Abstract
The present research was performed to assess the effect of 24-epibrassinolide (EBR) on salt-stressed soybean plants. Salt stress suppressed growth, biomass yield, gas exchange parameters, pigment content, and chlorophyll fluorescence, but all these parameters were up-regulated by EBR supply. Moreover, salt stress increased [...] Read more.
The present research was performed to assess the effect of 24-epibrassinolide (EBR) on salt-stressed soybean plants. Salt stress suppressed growth, biomass yield, gas exchange parameters, pigment content, and chlorophyll fluorescence, but all these parameters were up-regulated by EBR supply. Moreover, salt stress increased hydrogen peroxide, malondialdehyde, and electrolyte leakage. EBR supplementation reduced the accumulation of oxidative stress biomarkers. The activities of superoxide dismutase and catalase, and the accumulation of proline, glycinebetaine, total phenols, and total flavonoids increased with NaCl stress, but these attributes further increased with EBR supplementation. The activities of enzymes and the levels of non-enzymatic antioxidants involved in the Asc-Glu cycle also increased with NaCl stress, and further enhancement in these attributes was recorded by EBR supplementation. Salinity elevated the methylglyoxal content, but it was decreased by the EBR supplementation accompanying with up-regulation of the glyoxalase cycle (GlyI and GlyII). Salinity enhanced the Na+ uptake in root and shoot coupled with a decrease in uptake of Ca2+, K+, and P. However, EBR supplementation declined Na+ accumulation and promoted the uptake of the aforementioned nutrients. Overall, EBR supplementation regulated the salt tolerance mechanism in soybean plants by modulating osmolytes, activities of key enzymes, and the levels of non-enzymatic antioxidants. Full article
(This article belongs to the Special Issue Phytohormones)
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18 pages, 2844 KiB  
Article
GLYI4 Plays A Role in Methylglyoxal Detoxification and Jasmonate-Mediated Stress Responses in Arabidopsis thaliana
by Silvia Proietti, Gaia Salvatore Falconieri, Laura Bertini, Ivan Baccelli, Elena Paccosi, Antonio Belardo, Anna Maria Timperio and Carla Caruso
Biomolecules 2019, 9(10), 635; https://doi.org/10.3390/biom9100635 - 22 Oct 2019
Cited by 19 | Viewed by 4634
Abstract
Plant hormones play a central role in various physiological functions and in mediating defense responses against (a)biotic stresses. In response to primary metabolism alteration, plants can produce also small molecules such as methylglyoxal (MG), a cytotoxic aldehyde. MG is mostly detoxified by the [...] Read more.
Plant hormones play a central role in various physiological functions and in mediating defense responses against (a)biotic stresses. In response to primary metabolism alteration, plants can produce also small molecules such as methylglyoxal (MG), a cytotoxic aldehyde. MG is mostly detoxified by the combined actions of the enzymes glyoxalase I (GLYI) and glyoxalase II (GLYII) that make up the glyoxalase system. Recently, by a genome-wide association study performed in Arabidopsis, we identified GLYI4 as a novel player in the crosstalk between jasmonate (JA) and salicylic acid (SA) hormone pathways. Here, we investigated the impact of GLYI4 knock-down on MG scavenging and on JA pathway. In glyI4 mutant plants, we observed a general stress phenotype, characterized by compromised MG scavenging, accumulation of reactive oxygen species (ROS), stomatal closure, and reduced fitness. Accumulation of MG in glyI4 plants led to lower efficiency of the JA pathway, as highlighted by the increased susceptibility of the plants to the pathogenic fungus Plectospherella cucumerina. Moreover, MG accumulation brought about a localization of GLYI4 to the plasma membrane, while MeJA stimulus induced a translocation of the protein into the cytoplasmic compartment. Collectively, the results are consistent with the hypothesis that GLYI4 is a hub in the MG and JA pathways. Full article
(This article belongs to the Special Issue Phytohormones)
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17 pages, 3772 KiB  
Article
New Insights into Structural and Functional Roles of Indole-3-acetic acid (IAA): Changes in DNA Topology and Gene Expression in Bacteria
by Roberto Defez, Anna Valenti, Anna Andreozzi, Silvia Romano, Maria Ciaramella, Paolo Pesaresi, Sara Forlani and Carmen Bianco
Biomolecules 2019, 9(10), 522; https://doi.org/10.3390/biom9100522 - 23 Sep 2019
Cited by 7 | Viewed by 3971
Abstract
Indole-3-acetic acid (IAA) is a major plant hormone that affects many cellular processes in plants, bacteria, yeast, and human cells through still unknown mechanisms. In this study, we demonstrated that the IAA-treatment of two unrelated bacteria, the Ensifer meliloti 1021 and Escherichia coli, [...] Read more.
Indole-3-acetic acid (IAA) is a major plant hormone that affects many cellular processes in plants, bacteria, yeast, and human cells through still unknown mechanisms. In this study, we demonstrated that the IAA-treatment of two unrelated bacteria, the Ensifer meliloti 1021 and Escherichia coli, harboring two different host range plasmids, influences the supercoiled state of the two plasmid DNAs in vivo. Results obtained from in vitro assays show that IAA interacts with DNA, leading to DNA conformational changes commonly induced by intercalating agents. We provide evidence that IAA inhibits the activity of the type IA topoisomerase, which regulates the DNA topological state in bacteria, through the relaxation of the negative supercoiled DNA. In addition, we demonstrate that the treatment of E. meliloti cells with IAA induces the expression of some genes, including the ones related to nitrogen fixation. In contrast, these genes were significantly repressed by the treatment with novobiocin, which reduces the DNA supercoiling in bacterial cells. Taking into account the overall results reported, we hypothesize that the IAA action and the DNA structure/function might be correlated and involved in the regulation of gene expression. This work points out that checking whether IAA influences the DNA topology under physiological conditions could be a useful strategy to clarify the mechanism of action of this hormone, not only in plants but also in other unrelated organisms. Full article
(This article belongs to the Special Issue Phytohormones)
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6 pages, 231 KiB  
Communication
Proteolytic Activity in Meadow Soil after the Application of Phytohormones
by Ladislav Holik and Valerie Vranová
Biomolecules 2019, 9(9), 507; https://doi.org/10.3390/biom9090507 - 19 Sep 2019
Cited by 3 | Viewed by 2711
Abstract
Phytohormones, similar to soil enzymes, are synthesized and secreted into the soil environment by fungi and microorganisms. Phytohormones are involved in regulating microbial community activity in the rhizosphere. This paper examines how auxins, cytokinins, ethephon and chlorocholine chloride affect the activity of native [...] Read more.
Phytohormones, similar to soil enzymes, are synthesized and secreted into the soil environment by fungi and microorganisms. Phytohormones are involved in regulating microbial community activity in the rhizosphere. This paper examines how auxins, cytokinins, ethephon and chlorocholine chloride affect the activity of native soil proteases in the organo-mineral horizon of an alpine meadow. In the meadow habitat, native soil proteases were inhibited by auxins whereas the effect of cytokinins on these enzymes was not statistically significant. A similar inhibitory effect on the activity of proteases was shown for ethephon and chlorocholine chloride, both of which also inhibited the activity of native soil proteases in the alpine meadow soil. Overall, the inhibitory effect of phytohormones on the activity of native protease activity may affect plant nutrition by retarding the nitrogen cycle in the soil. This work contributes to our understanding of the influence of substances produced by the rhizosphere that can actively participate in the activity of soil microorganisms and consequently influence the soil nitrogen cycle. Full article
(This article belongs to the Special Issue Phytohormones)
14 pages, 3164 KiB  
Article
Comparative Physiological Analysis of Methyl Jasmonate in the Delay of Postharvest Physiological Deterioration and Cell Oxidative Damage in Cassava
by Guoyin Liu, Bing Li, Xiuqiong Li, Yunxie Wei, Debing Liu and Haitao Shi
Biomolecules 2019, 9(9), 451; https://doi.org/10.3390/biom9090451 - 5 Sep 2019
Cited by 16 | Viewed by 3248
Abstract
The short postharvest life of cassava is mainly due to its rapid postharvest physiological deterioration (PPD) and cell oxidative damage, however, how to effectively control this remains elusive. In this study, South China 5 cassava slices were sprayed with water and methyl jasmonate [...] Read more.
The short postharvest life of cassava is mainly due to its rapid postharvest physiological deterioration (PPD) and cell oxidative damage, however, how to effectively control this remains elusive. In this study, South China 5 cassava slices were sprayed with water and methyl jasmonate (MeJA) to study the effects of MeJA on reactive oxygen species, antioxidant enzymes, quality, endogenous hormone levels, and melatonin biosynthesis genes. We found that exogenous MeJA could delay the deterioration rate for at least 36 h and alleviate cell oxidative damage through activation of superoxide dismutase, catalase, and peroxidase. Moreover, MeJA increased the concentrations of melatonin and gibberellin during PPD, which had a significant effect on regulating PPD. Notably, exogenous MeJA had a significant effect on maintaining cassava quality, as evidenced by increased ascorbic acid content and carotenoid content. Taken together, MeJA treatment is an effective and promising way to maintain a long postharvest life, alleviate cell oxidative damage, and regulate storage quality in cassava. Full article
(This article belongs to the Special Issue Phytohormones)
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16 pages, 3885 KiB  
Article
System Analysis of MIRNAs in Maize Internode Elongation
by Chuanxi Peng, Xing Wang, Tianyu Feng, Rui He, Mingcai Zhang, Zhaohu Li, Yuyi Zhou and Liusheng Duan
Biomolecules 2019, 9(9), 417; https://doi.org/10.3390/biom9090417 - 27 Aug 2019
Cited by 10 | Viewed by 3746
Abstract
MicroRNAs (miRNAs), the post-transcriptional gene regulators, are known to play an important role in plant development. The identification of differentially expressed miRNAs could better help us understand the post-transcriptional regulation that occurs during maize internode elongation. Accordingly, we compared the expression of MIRNAs [...] Read more.
MicroRNAs (miRNAs), the post-transcriptional gene regulators, are known to play an important role in plant development. The identification of differentially expressed miRNAs could better help us understand the post-transcriptional regulation that occurs during maize internode elongation. Accordingly, we compared the expression of MIRNAs between fixed internode and elongation internode samples and classified six differentially expressed MIRNAs as internode elongation-responsive miRNAs including zma-MIR160c, zma-MIR164b, zma-MIR164c, zma-MIR168a, zma-MIR396f, and zma-MIR398b, which target mRNAs supported by transcriptome sequencing. Functional enrichment analysis for predictive target genes showed that these miRNAs were involved in the development of internode elongation by regulating the genes respond to hormone signaling. To further reveal how miRNA affects internode elongation by affecting target genes, the miRNA–mRNA–PPI (protein and protein interaction) network was constructed to summarize the interaction of miRNAs and these target genes. Our results indicate that miRNAs regulate internode elongation in maize by targeting genes related to cell expansion, cell wall synthesis, transcription, and regulatory factors. Full article
(This article belongs to the Special Issue Phytohormones)
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Review

Jump to: Research, Other

20 pages, 2113 KiB  
Review
Molecular Responses during Plant Grafting and Its Regulation by Auxins, Cytokinins, and Gibberellins
by Anket Sharma and Bingsong Zheng
Biomolecules 2019, 9(9), 397; https://doi.org/10.3390/biom9090397 - 22 Aug 2019
Cited by 43 | Viewed by 6731
Abstract
Plant grafting is an important horticulture technique used to produce a new plant after joining rootstock and scion. This is one of the most used techniques by horticulturists to enhance the quality and production of various crops. Grafting helps in improving the health [...] Read more.
Plant grafting is an important horticulture technique used to produce a new plant after joining rootstock and scion. This is one of the most used techniques by horticulturists to enhance the quality and production of various crops. Grafting helps in improving the health of plants, their yield, and the quality of plant products, along with the enhancement of their postharvest life. The main process responsible for successful production of grafted plants is the connection of vascular tissues. This step determines the success rate of grafts and hence needs to be studied in detail. There are many factors that regulate the connection of scion and stock, and plant hormones are of special interest for researchers in the recent times. These phytohormones act as signaling molecules and have the capability of translocation across the graft union. Plant hormones, mainly auxins, cytokinins, and gibberellins, play a major role in the regulation of various key physiological processes occurring at the grafting site. In the current review, we discuss the molecular mechanisms of graft development and the phytohormone-mediated regulation of the growth and development of graft union. Full article
(This article belongs to the Special Issue Phytohormones)
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36 pages, 1792 KiB  
Review
Phytohormones Regulate Accumulation of Osmolytes Under Abiotic Stress
by Anket Sharma, Babar Shahzad, Vinod Kumar, Sukhmeen Kaur Kohli, Gagan Preet Singh Sidhu, Aditi Shreeya Bali, Neha Handa, Dhriti Kapoor, Renu Bhardwaj and Bingsong Zheng
Biomolecules 2019, 9(7), 285; https://doi.org/10.3390/biom9070285 - 17 Jul 2019
Cited by 457 | Viewed by 16632
Abstract
Plants face a variety of abiotic stresses, which generate reactive oxygen species (ROS), and ultimately obstruct normal growth and development of plants. To prevent cellular damage caused by oxidative stress, plants accumulate certain compatible solutes known as osmolytes to safeguard the cellular machinery. [...] Read more.
Plants face a variety of abiotic stresses, which generate reactive oxygen species (ROS), and ultimately obstruct normal growth and development of plants. To prevent cellular damage caused by oxidative stress, plants accumulate certain compatible solutes known as osmolytes to safeguard the cellular machinery. The most common osmolytes that play crucial role in osmoregulation are proline, glycine-betaine, polyamines, and sugars. These compounds stabilize the osmotic differences between surroundings of cell and the cytosol. Besides, they also protect the plant cells from oxidative stress by inhibiting the production of harmful ROS like hydroxyl ions, superoxide ions, hydrogen peroxide, and other free radicals. The accumulation of osmolytes is further modulated by phytohormones like abscisic acid, brassinosteroids, cytokinins, ethylene, jasmonates, and salicylic acid. It is thus important to understand the mechanisms regulating the phytohormone-mediated accumulation of osmolytes in plants during abiotic stresses. In this review, we have discussed the underlying mechanisms of phytohormone-regulated osmolyte accumulation along with their various functions in plants under stress conditions. Full article
(This article belongs to the Special Issue Phytohormones)
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Other

Jump to: Research, Review

6 pages, 2052 KiB  
Commentary
Cytokinin Sensing in Bacteria
by Samar Kabbara, Baptiste Bidon, Jaafar Kilani, Marwan Osman, Monzer Hamze, Ann M. Stock and Nicolas Papon
Biomolecules 2020, 10(2), 186; https://doi.org/10.3390/biom10020186 - 25 Jan 2020
Cited by 6 | Viewed by 3071
Abstract
Although it has long been known that bacteria detect and react to plant chemicals to establish an interaction, the cellular signaling mechanisms involved in these perception processes have hitherto remained obscure. Some exciting recent advances in the field have described, for the first [...] Read more.
Although it has long been known that bacteria detect and react to plant chemicals to establish an interaction, the cellular signaling mechanisms involved in these perception processes have hitherto remained obscure. Some exciting recent advances in the field have described, for the first time, how some phytopathogenic bacteria sense the host plant hormones, cytokinins. These discoveries not only advance the understanding of cell signaling circuitries engaged in cytokinin sensing in non-plant organisms, but also increase our knowledge of the broad role of these ancient molecules in regulating intra- and interspecific communications. Full article
(This article belongs to the Special Issue Phytohormones)
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