Institutional Publications

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Author: search.filters.author.Laxmi, AshveryaSubject: search.filters.subject.phytohormones

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    Jasmonic acid coordinates with light, glucose and auxin signalling in regulating branching angle of Arabidopsis lateral roots
    (John Wiley & Sons, 2022) Sharma, Manvi; Sharma, Mohan; Jamsheer, K. Muhammed; Laxmi, Ashverya
    The role of jasmonates (JAs) in primary root growth and development and in plant response to external stimuli is already known. However, its role in lateral root (LR) development remains to be explored. Our work identified methyl jasmonate (MeJA) as a key phytohormone in determining the branching angle of Arabidopsis LRs. MeJA inclines the LRs to a more vertical orientation, which was dependent on the canonical JAR1-COI1-MYC2,3,4 signalling. Our work also highlights the dual roles of light in governing LR angle. Light signalling enhances JA biosynthesis, leading to erect root architecture; whereas, glucose (Glc) induces wider branching angles. Combining physiological and molecular assays, we revealed that Glc antagonizes the MeJA response via TARGET OF RAPAMYCIN (TOR) signalling. Moreover, physiological assays using auxin mutants, MYC2-mediated transcriptional activation of LAZY2, LAZY4 and auxin biosynthetic gene CYP79B2,and asymmetric distribution of DR5::GFP and PIN2::GFP pinpointed the role of an intact auxin mechanism required by MeJA for vertical growth of LRs. We also demonstrated that light perception and signalling are indispensable for inducing vertical angles by MeJA. Thus, our investigation highlights antagonism between light and Glc signalling and how they interact with JA-auxin signals to optimize the branching angle of LRs.
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    The versatile role of glucose signalling in regulating growth, development and stress responses in plants
    (Springer Nature Publishing AG, 2020) Saksena, Harshita B.; Sharma, Manvi; Singh, Dhriti; Laxmi, Ashverya
    Sugars as an energy source and a signalling molecule are indispensible for growth, development and stress responses in plants. Among sugars, glucose (Glc) has been identified to perform a key role in regulating various cellular and developmental processes in plants. This comprehensive review highlights the crosstalk of glucose signalling with auxin, cytokinin and brassinosteroid signalling in controlling several aspects of plant development including root growth deviation, root waving and coiling, lateral root emergence, hypocotyl elongation, etc. through a Hexokinase 1 dependent and independent pathway in Arabidopsis. It also provides an insight on the role of Glc-mediated target of rapamycin signalling in modulating various abiotic stresses like nutrient deficiency stress, heat stress, oxidative stress etc. The review also discusses about sugar inducible FCS-Like Zinc Finger genes in modulating SNF1-related protein kinase 1 signalling to coordinate growth and stress responses in plants. Therefore, glucose signalling in concert with diverse signalling pathways and via regulating certain genes contributes to numerous cellular processes to control development and stress responses in plants.
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    Striking the right chord: Signaling enigma during root gravitropism
    (Frontiers Media S.A., 2017) Singh, Manjul; Gupta, Aditi; Laxmi, Ashverya
    Plants being sessile can often be judged as passive acceptors of their environment. However, plants are actually even more active in responding to the factors from their surroundings. Plants do not have eyes, ears or vestibular system like animals, still they "know" which way is up and which way is down? This is facilitated by receptor molecules within plant which perceive changes in internal and external conditions such as light, touch, obstacles; and initiate signaling pathways that enable the plant to react. Plant responses that involve a definite and specific movement are called "tropic" responses. Perhaps the best known and studied tropisms are phototropism, i.e., response to light, and geotropism, i.e., response to gravity. A robust root system is vital for plant growth as it can provide physical anchorage to soil as well as absorb water, nutrients and essential minerals from soil efficiently. Gravitropic responses of both primary as well as lateral root thus become critical for plant growth and development. The molecular mechanisms of root gravitropism has been delved intensively, however, the mechanism behind how the potential energy of gravity stimulus converts into a biochemical signal in vascular plants is still unknown, due to which gravity sensing in plants still remains one of the most fascinating questions in molecular biology. Communications within plants occur through phytohormones and other chemical substances produced in plants which have a developmental or physiological effect on growth. Here, we review current knowledge of various intrinsic signaling mechanisms that modulate root gravitropism in order to point out the questions and emerging developments in plant directional growth responses. We are also discussing the roles of sugar signals and their interaction with phytohormone machinery, specifically in context of root directional responses.