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Thiourea priming enhances salt tolerance through co-ordinated regulation of microRNAs and hormones in Brassica juncea

View Article: PubMed Central - PubMed

ABSTRACT

Activation of stress tolerance mechanisms demands transcriptional reprogramming. Salt stress, a major threat to plant growth, enhances ROS production and affects transcription through modulation of miRNAs and hormones. The present study delineates salt stress ameliorating action of thiourea (TU, a ROS scavenger) in Brassica juncea and provides mechanistic link between redox, microRNA and hormones. The ameliorative potential of TU towards NaCl stress was related with its ability to decrease ROS accumulation in roots and increase Na+ accumulation in shoots. Small RNA sequencing revealed enrichment of down-regulated miRNAs in NaCl + TU treated roots, indicating transcriptional activation. Ranking analysis identified three key genes including BRX4, CBL10 and PHO1, showing inverse relationship with corresponding miRNA expression, which were responsible for TU mediated stress mitigation. Additionally, ABA level was consistently higher till 24 h in NaCl, while NaCl + TU treated roots showed only transient increase at 4 h suggesting an effective stress management. Jasmonate and auxin levels were also increased, which prioritized defence and facilitated root growth, respectively. Thus, the study highlights redox as one of the “core” components regulating miRNA and hormone levels, and also strengthens the use of TU as a redox priming agent for imparting crop resilience to salt stress.

No MeSH data available.


Redox, miRNA and hormone based bifurcative model in B. juncea.The redox-state acts as a central point to regulate both miRNA and hormone levels through a bifurcative mechanisms. Owing to its scavenging action, TU supplementation helps in reducing ROS levels in seedling under NaCl treatment. This alters miRNA mediated post-transcriptional regulation by two ways. Firstly, miRNAs expressions were down-regulated and secondly, miRNA:mRNA interaction gets deregulated. As a parallel mechanism, redox balancing helps in activating different hormones in a co-ordianted manner, which maximizes the positive impact of TU supplementation. The ABA level was regulated temporally which facilitated the induction of jasmonate to prioritize defence over growth in NaCl + TU treatment. In contrast, ABA level was consistently high under NaCl and hence, jasmonate increase was not seen. The auxin level was also higher in NaCl + TU than NaCl which supports root growth. The cumulative impact of miRNA and hormone mediated changes were reflected in terms of improved plant growth under NaCl + TU as compared with NaCl treatment.
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f6: Redox, miRNA and hormone based bifurcative model in B. juncea.The redox-state acts as a central point to regulate both miRNA and hormone levels through a bifurcative mechanisms. Owing to its scavenging action, TU supplementation helps in reducing ROS levels in seedling under NaCl treatment. This alters miRNA mediated post-transcriptional regulation by two ways. Firstly, miRNAs expressions were down-regulated and secondly, miRNA:mRNA interaction gets deregulated. As a parallel mechanism, redox balancing helps in activating different hormones in a co-ordianted manner, which maximizes the positive impact of TU supplementation. The ABA level was regulated temporally which facilitated the induction of jasmonate to prioritize defence over growth in NaCl + TU treatment. In contrast, ABA level was consistently high under NaCl and hence, jasmonate increase was not seen. The auxin level was also higher in NaCl + TU than NaCl which supports root growth. The cumulative impact of miRNA and hormone mediated changes were reflected in terms of improved plant growth under NaCl + TU as compared with NaCl treatment.

Mentions: In conclusion, present study utilized the exogenous application of TU, a non-physiological thiol and ROS scavenger, to develop redox regulated miRNA and hormone based regulatory module operative under NaCl stress condition (Fig. 6). The supplementation of TU modulates post-transcriptional gene regulation to enhance the expression of salt tolerance related genes. This is mediated either through down-regulation of miRNA expression or via one of the possible mechanisms of decoupling miRNA:mRNA inverse relationship. Simultaneous to this, levels of different hormones were co-ordinated to maximize TU mediated ameliorative effect. ABA level was regulated temporally which facilitated the induction of jasmonate to prioritize defense over growth in NaCl + TU treatment. This was supported from higher level of auxin which reduced the toxicity on root growth. The overall effect was reflected in the form of improved growth phenotype. Thus, the study highlights the significance of redox homeostasis, as one of the “core” regulators, for mediating miRNA and hormone based regulation through a bifurcative mechanism. Additionally, the mechanistic basis for salt-ameliorating action of TU has also been provided which ensures wider adoptability of TU-based formulations for imparting crop resilience to salt stress under farmer’s field condition.


Thiourea priming enhances salt tolerance through co-ordinated regulation of microRNAs and hormones in Brassica juncea
Redox, miRNA and hormone based bifurcative model in B. juncea.The redox-state acts as a central point to regulate both miRNA and hormone levels through a bifurcative mechanisms. Owing to its scavenging action, TU supplementation helps in reducing ROS levels in seedling under NaCl treatment. This alters miRNA mediated post-transcriptional regulation by two ways. Firstly, miRNAs expressions were down-regulated and secondly, miRNA:mRNA interaction gets deregulated. As a parallel mechanism, redox balancing helps in activating different hormones in a co-ordianted manner, which maximizes the positive impact of TU supplementation. The ABA level was regulated temporally which facilitated the induction of jasmonate to prioritize defence over growth in NaCl + TU treatment. In contrast, ABA level was consistently high under NaCl and hence, jasmonate increase was not seen. The auxin level was also higher in NaCl + TU than NaCl which supports root growth. The cumulative impact of miRNA and hormone mediated changes were reflected in terms of improved plant growth under NaCl + TU as compared with NaCl treatment.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5382540&req=5

f6: Redox, miRNA and hormone based bifurcative model in B. juncea.The redox-state acts as a central point to regulate both miRNA and hormone levels through a bifurcative mechanisms. Owing to its scavenging action, TU supplementation helps in reducing ROS levels in seedling under NaCl treatment. This alters miRNA mediated post-transcriptional regulation by two ways. Firstly, miRNAs expressions were down-regulated and secondly, miRNA:mRNA interaction gets deregulated. As a parallel mechanism, redox balancing helps in activating different hormones in a co-ordianted manner, which maximizes the positive impact of TU supplementation. The ABA level was regulated temporally which facilitated the induction of jasmonate to prioritize defence over growth in NaCl + TU treatment. In contrast, ABA level was consistently high under NaCl and hence, jasmonate increase was not seen. The auxin level was also higher in NaCl + TU than NaCl which supports root growth. The cumulative impact of miRNA and hormone mediated changes were reflected in terms of improved plant growth under NaCl + TU as compared with NaCl treatment.
Mentions: In conclusion, present study utilized the exogenous application of TU, a non-physiological thiol and ROS scavenger, to develop redox regulated miRNA and hormone based regulatory module operative under NaCl stress condition (Fig. 6). The supplementation of TU modulates post-transcriptional gene regulation to enhance the expression of salt tolerance related genes. This is mediated either through down-regulation of miRNA expression or via one of the possible mechanisms of decoupling miRNA:mRNA inverse relationship. Simultaneous to this, levels of different hormones were co-ordinated to maximize TU mediated ameliorative effect. ABA level was regulated temporally which facilitated the induction of jasmonate to prioritize defense over growth in NaCl + TU treatment. This was supported from higher level of auxin which reduced the toxicity on root growth. The overall effect was reflected in the form of improved growth phenotype. Thus, the study highlights the significance of redox homeostasis, as one of the “core” regulators, for mediating miRNA and hormone based regulation through a bifurcative mechanism. Additionally, the mechanistic basis for salt-ameliorating action of TU has also been provided which ensures wider adoptability of TU-based formulations for imparting crop resilience to salt stress under farmer’s field condition.

View Article: PubMed Central - PubMed

ABSTRACT

Activation of stress tolerance mechanisms demands transcriptional reprogramming. Salt stress, a major threat to plant growth, enhances ROS production and affects transcription through modulation of miRNAs and hormones. The present study delineates salt stress ameliorating action of thiourea (TU, a ROS scavenger) in Brassica juncea and provides mechanistic link between redox, microRNA and hormones. The ameliorative potential of TU towards NaCl stress was related with its ability to decrease ROS accumulation in roots and increase Na+ accumulation in shoots. Small RNA sequencing revealed enrichment of down-regulated miRNAs in NaCl + TU treated roots, indicating transcriptional activation. Ranking analysis identified three key genes including BRX4, CBL10 and PHO1, showing inverse relationship with corresponding miRNA expression, which were responsible for TU mediated stress mitigation. Additionally, ABA level was consistently higher till 24 h in NaCl, while NaCl + TU treated roots showed only transient increase at 4 h suggesting an effective stress management. Jasmonate and auxin levels were also increased, which prioritized defence and facilitated root growth, respectively. Thus, the study highlights redox as one of the “core” components regulating miRNA and hormone levels, and also strengthens the use of TU as a redox priming agent for imparting crop resilience to salt stress.

No MeSH data available.