Browsing by Author "Pandey, Anshika"

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The interplay of auxin and brassinosteroid signaling tunes root growth under low and different nitrogen forms
(Oxford University Press, 2022) Devi, Loitongbam Lorinda; Pandey, Anshika; Gupta, Shreya; Singh, Amar Pal
The coordinated signaling activity of auxin and brassinosteroids (BRs) is critical for optimal plant growth and development. Nutrient-derived signals regulate root growth by modulating the levels and spatial distribution of growth hormones to optimize nutrient uptake and assimilation. However, the effect of the interaction of these two hormones and their signaling on root plasticity during low and differential availability of nitrogen (N) forms (NH4+/NO3-) remains elusive. We demonstrate that root elongation under low nitrogen (LN) is an outcome of the interdependent activity of auxin and BR signaling pathways in Arabidopsis (Arabidopsis thaliana). LN promotes root elongation by increasing BR-induced auxin transport activity in the roots. Increased nuclear auxin signaling and its transport efficiency have a distinct impact on root elongation under LN conditions. High auxin levels reversibly inhibit BR signaling via BRI1 KINASE INHIBITOR1 (BKI1). Using the tissue-specific approach, we show that BR signaling from root vasculature (stele) tissues is sufficient to promote cell elongation and, hence, root growth under LN condition. Further, we show that N form-defined root growth attenuation or enhancement depends on the fine balance of BR and auxin signaling activity. NH4+ as a sole N source represses BR signaling and response, which in turn inhibits auxin response and transport, whereas NO3- promotes root elongation in a BR signaling–dependent manner. In this study, we demonstrate the interplay of auxin and BR-derived signals, which are critical for root growth in a heterogeneous N environment and appear essential for root N foraging response and adaptation.
Jasmonate signaling modulates root growth by suppressing iron accumulation during ammonium stress
(Oxford University Press, 2024) Pandey, Anshika; Devi, Loitongbam Lorinda; Gupta, Shreya; Prasad, Priti; Agrwal, Kanupriya; Asif, Mehar Hasan; Pandey, Ajay Kumar; Bandyopadhyay, Kaustav; Singh, Amar Pal
Plants adapt to changing environmental conditions by adjusting their growth physiology. Nitrate (NO3-) and ammonium (NH4+) are the major inorganic nitrogen forms for plant uptake. However, high NH4+ inhibits plant growth, and roots undergo striking changes, such as inhibition of cell expansion and division, leading to reduced root elongation. In this work, we show that high NH4+ modulates nitrogen metabolism and root developmental physiology by inhibiting iron (Fe)-dependent Jasmonate (JA) signaling and response in Arabidopsis (Arabidopsis thaliana). Transcriptomic data suggested that NH4+ availability regulates Fe and JA-responsive genes. High NH4+ levels led to enhanced root Fe accumulation, which impaired nitrogen balance and growth by suppressing JA biosynthesis and signaling response. Integrating pharmacological, physiological, and genetic experiments revealed the involvement of NH4+ and Fe-derived responses in regulating root growth and nitrogen metabolism through modulation of the JA pathway during NH4+ stress. The JA signaling transcription factor MYC2 directly bound the promoter of the NITRATE TRANSPORTER 1.1 (NRT1.1) and repressed it to optimize the NH4+/Fe-JA balance for plant adaptation during NH4+ stress. Our findings illustrate the intricate balance between nutrient and hormone-derived signaling pathways that appear essential for optimizing plant growth by adjusting physiological and metabolic responses during NH4+/Fe stress.
Nitrogen forms and their availability-dependent root developmental adaptation in plants
(Elsevier B.V., 2024) Pandey, Anshika; Singh, Kratika; Singh, Amar Pal
Nitrogen (N) is one of the crucial nutrients required for the growth and development of plants. The two predominant forms of N acquired by terrestrial plants are nitrate (NO3−) and ammonium (NH4+). Due to the leaching behavior of these forms, N often ends up being the limiting nutrient for crop plants. Postgreen revolution strategies of accelerated crop production necessitated the heavy application of N fertilizers, a large portion of which succumbs to air and water. To adapt to varying levels of NO3− and NH4+ and under their low availability, plants have inherent mechanisms of altering their root system architecture (RSA), a phenomenon termed as N foraging response. Knowledge about the biochemical mechanisms and genetic aspects behind N source preference and root plasticity is vast but scattered. In this chapter, we attempt to put forward the coordination of primary root (PR) and lateral root (LR) development by intrinsic factors such as growth regulators and N metabolites in an N-form-specific manner. The influence of N interaction with other nutrients on root development has also been featured.
Review: Emerging roles of brassinosteroid in nutrient foraging
(Elsevier B.V., 2020) Pandey, Anshika; Devi, Loitongbam Lorinda; Singh, Amar Pal
Brassinosteroids (BRs) are well-characterized growth hormones that are critical for plant growth, development, and productivity. Genetic and molecular studies have revealed the key components of BR biosynthesis and signaling pathways. The membrane-localized BR signaling receptor, BRASSINOSTEROID INSENSITIVE1 (BRI1) binds directly to its ligand and initiates series of signaling events that led to the activation of BR transcriptional regulators, BRASSINAZOLE RESISTANT1 (BZR1) and BRI1-ETHYL METHANESULFONATE-SUPPRESSOR1 (BES1/BZR2) to regulate the cellular processes. Insights from Arabidopsis research revealed tissue and cell typespecific roles of BR in controlling cell elongation and maintenance of stem cell niche in roots. More recently, BRs have gained much attention in regulating the root growth during nutrient deficiency such as nitrogen, phosphorus, and boron. Differential distribution of nutrients in the rhizosphere alters BR hormone levels and signaling to reprogram spatial distribution of root system architecture (RSA) such as a change in primary root growth, lateral root numbers, length, and angle, root hair formation and elongation. These morpho-physiological changes in RSA are also known as an adaptive root trait or foraging response of the plant. In this review, we highlight the role of BRs in regulating RSA to increase root foraging response during fluctuating nutrient availability.