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Photoperiodic responses shape plant fitness to the changing environment and are important regulators of growth, development, and productivity. Photoperiod sensing is one of the most important cues to track seasonal variations. It is also a major cue for reproductive success. The photoperiodic information conveyed through the combined action of photoreceptors and the circadian clock orchestrates an output response in plants. Multiple responses such as hypocotyl elongation, induction of dormancy, and flowering are photoperiodically regulated in seed plants (eg. angiosperms). Flowering plants such as Arabidopsis or rice have served as important model systems to understand the molecular players involved in photoperiodic signalling. However, photoperiodic responses in non-angiosperm plants have not been investigated and documented in detail. Genomic and transcriptomic studies have provided evidence on the conserved and distinct molecular mechanisms across the plant kingdom. In this review, we have attempted to compile and compare photoperiodic responses in the plant kingdom with a special focus on non-angiosperms., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

GIGANTEA (GI) is a multifaceted plant-specific protein that originated in a streptophyte ancestor. The current known functions of GI include circadian clock control, light signalling, flowering time regulation, stomata response, chloroplast biogenesis, accumulation of anthocyanin, chlorophyll, and starch, phytohormone signalling, senescence, and response to drought, salt, and oxidative stress. Six decades since its discovery, no functional domains have been defined, and its mechanism of action is still not well characterized. In this review, we explore the functional evolution of GI to distinguish between ancestral and more recently acquired roles. GI integrated itself into various existing signalling pathways of the circadian clock, blue light, photoperiod, and osmotic and oxidative stress response. It also evolved parallelly to acquire new functions for chloroplast accumulation, red light signalling, and anthocyanin production. In this review, we have encapsulated the known mechanisms of various biological functions of GI, and cast light on the evolution of GI in the plant lineage., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

The blooming industrialization and urbanization is leading to increased mining operations. These intensified mining activities emit heavy metals into the environment, posing serious threats to ecosystems. Hence, this study focused on assessing heavy metal pollution in mining soil, utilizing mosses as bioindicators. The ecological risk, geo-accumulation factor, and contamination factor have been calculated to know the harmful effect of heavy metals on ecosystem. The study covered three distinct mining sites of eastern India within Odisha: Jajpur's Sukinda Valley (SP1, Cr), Keonjhar's Joda-Barbil (SP2, Fe and Mn), and Sundargarh's Koira-Joda (SP3, Fe). The collection of 48 soil samples through random sampling revealed significant variations in heavy metal concentrations. SP1 recorded Cr concentration of 6572 ± 445 mg/kg and Ni of 8042.47 ± 501.38 mg/kg, surpassing eco-toxicological levels. The storage site in SP2 exhibited the highest Fe concentration at 9872 ± 502 mg/kg, and Mn levels in SP3 were at 7884 ± 432 mg/kg. Storage areas in all three regions held the highest concentrations of heavy metals. Mosses in studied area demonstrated as potential bioindicators for monitoring heavy metal pollution. EF and I geo assessments showed Cd, Pb, Hg, and other heavy metal contamination compared to earlier investigations. This study indicated higher ecological risks for Pb, As, Cu, Ni, and Zn. The Hyophila involuta accumulates Mn, Cr, Cd, Pb, Fe, and Hg, while Barbula arcuata accumulates Mn, As, and Cu in SP1. Hyophila involuta and Trematodon longicollis accumulate Mn, Cr, Cd, Pb, Fe, Hg, and Zn in SP2. Trematodon ambiguous accumulates Cd, Fe, and Ni, while Fissidens diversifolius accumulates Mn, Cr, Hg, As, Cu, and Zn in SP3. These findings emphasize the necessity of monitoring heavy metal pollution in contaminated zones using moss as a potential bioindicator., (© 2024. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

GIGANTEA (GI) is a plant-specific nuclear protein that plays a pleiotropic role in the growth and development of plants. GI's involvement in circadian clock function, flowering time regulation, and various types of abiotic stress tolerance has been well documented in recent years. Here, the role of GI in response to Fusarium oxysporum ( F. oxysporum ) infection is investigated at the molecular level comparing Col-0 WT with the gi-100 mutant in Arabidopsis thaliana . Disease progression, photosynthetic parameters, and comparative anatomy confirmed that the spread and damage caused by pathogen infection were less severe in gi-100 than in Col-0 WT plants. F. oxysporum infection induces a remarkable accumulation of GI protein. Our report showed that it is not involved in flowering time regulation during F. oxysporum infection. Estimation of defense hormone after infection showed that jasmonic acid (JA) level is higher and salicylic acid (SA) level is lower in gi-100 compared to Col-0 WT. Here, we show that the relative transcript expression of CORONATINE INSENSITIVE1 ( COI1 ) and PLANT DEFENSIN1.2 ( PDF1.2 ) as a marker of the JA pathway is significantly higher while ISOCHORISMATE SYNTHASE1 ( ICS1 ) and NON-EXPRESSOR OF PATHOGENESIS-RELATED GENES1 ( NPR1 ), the markers of the SA pathway, are downregulated in the gi-100 mutants compared to Col-0 plants. The present study convincingly suggests that the GI module promotes susceptibility to F. oxysporum infection by inducing the SA pathway and inhibiting JA signaling in A. thaliana ., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Patnaik, Kumar, Behera, Mishra, Dehery, Panigrahy, Das and Panigrahi.)

Main Conclusion: Circadian clock components exhibit structural variations in different plant systems, and functional variations during various abiotic stresses. These variations bear relevance for plant fitness and could be important evolutionarily. All organisms on earth have the innate ability to measure time as diurnal rhythms that occur due to the earth's rotations in a 24-h cycle. Circadian oscillations arising from the circadian clock abide by its fundamental properties of periodicity, entrainment, temperature compensation, and oscillator mechanism, which is central to its function. Despite the fact that a myriad of research in Arabidopsis thaliana illuminated many detailed aspects of the circadian clock, many more variations in clock components' organizations and functions remain to get deciphered. These variations are crucial for sustainability and adaptation in different plant systems in the varied environmental conditions in which they grow. Together with these variations, circadian clock functions differ drastically even during various abiotic and biotic stress conditions. The present review discusses variations in the organization of clock components and their role in different plant systems and abiotic stresses. We briefly introduce the clock components, entrainment, and rhythmicity, followed by the variants of the circadian clock in different plant types, starting from lower non-flowering plants, marine plants, dicots to the monocot crop plants. Furthermore, we discuss the interaction of the circadian clock with components of various abiotic stress pathways, such as temperature, light, water stress, salinity, and nutrient deficiency with implications for the reprogramming during these stresses. We also update on recent advances in clock regulations due to post-transcriptional, post-translation, non-coding, and micro-RNAs. Finally, we end this review by summarizing the points of applicability, a remark on the future perspectives, and the experiments that could clear major enigmas in this area of research., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Prolonged shade during the reproductive stage can result in significant yield losses in rice. For this study, we elucidated the role of microRNAs in prolonged-shade tolerance (~20 days of shade) in a shade-tolerant rice variety, Swarnaprabha (SP), in its reproductive stage using small RNA and degradome sequencing with expression analysis using microarray and qRT-PCR. This study demonstrates that miRNA (miR) regulation for shade-tolerance predominately comprises the deactivation of the miR itself, leading to the upregulation of their targets. Up- and downregulated differentially expressed miRs (DEms) presented drastic differences in the category of targets based on the function and pathway in which they are involved. Moreover, neutrally regulated and uniquely expressed miRs also contributed to the shade-tolerance response by altering the differential expression of their targets, probably due to their differential binding affinities. The upregulated DEms mostly targeted the cell wall, membrane, cytoskeleton, and cellulose synthesis-related transcripts, and the downregulated DEms targeted the transcripts of photosynthesis, carbon and sugar metabolism, energy metabolism, and amino acid and protein metabolism. We identified 16 miRNAs with 21 target pairs, whose actions may significantly contribute to the shade-tolerance phenotype and sustainable yield of SP. The most notable among these were found to be miR5493 - OsSLAC and miR5144 - OsLOG1 for enhanced panicle size, miR5493 - OsBRITTLE1-1 for grain formation, miR6245- OsCsIF9 for decreased stem mechanical strength, miR5487 - OsGns9 and miR168b - OsCP1 for better pollen development, and miR172b - OsbHLH153 for hyponasty under shade.

Growth and development of Physcomitrium patens is endogenously regulated by phytohormones such as auxin and cytokinin. Auxin induces the transition of chloronema to caulonema. This transition is also regulated by additional factors such as quantity and quality of light, carbon supply, and other phytohormones such as strigolactones and precursors of gibberrelic acid. On the other hand, cytokinins induce the formation of bud initials following caulonema differentiation. However, the influence of external factors such as light or nutrient supply on cytokinin-mediated bud initial formation has not been demonstrated in Physcomitrium patens . This study deals with the effect of light quality and nutrient supply on cytokinin-mediated bud initial formation. Bud initial formation has been observed in wild type plants in different light conditions such as white, red, and blue light in response to exogenously supplied cytokinin as well as glucose. In addition, budding assay has been demonstrated in the cry1a mutant of Physcomitrium in different light conditions. The results indicate that carbon supply and red light enhance the cytokinin response, while blue light inhibits this process in Physcomitrium .

Control of stage specific spike in ethylene production at anthesis has been a vauable route to potentially enhance genetic ceiling for grain filling of rice spikelet. A number of genes controlling ethylene homeostasis and starch synthesis have been identified so long, but lack of credible information on master modulation of gene expression by miRNAs and their target genes associated with hormonal dynamics obfuscate mechanisms controlling genotype difference in quantum of grain filling. The confusion accounts for consequent shrinkage of options for yield manipulation. In a two by two factorial design, miRNA regulation of spikelet specific grain development in low against high sterile recombinant inbred lines of rice Oryza sativa L. namely CR 3856-62-11-3-1-1-1-1-1-1 (SR 157) and CR 3856-63-1-1-1-1-1-1-1 (SR 159) respectively, and inferior verses superior spikelets were compared during first 10 days after anthesis. Grain filling was poorer in SR159 than SR157 and inferior spikelets in the former were most vulnerable. Between the cultivars, overall expression of unique miRNAs with targets on ethylene pathway genes was higher in SR159 than SR157 and the situation was opposite for auxin pathway genes. Precision analysis in psTarget server database identified up-regulation of MIR2877 and MIR530-5p having Os11t0141000-02 and Os07t0239400-01 (PP2A regulatory subunit-like protein and ethylene-responsive small GTP-binding proteins) and MIR396h having Os01t0643300-02 (an auxin efflux carrier protein) and Os01t0643300-01 (a PIN1-like auxin transport protein), as targets with highest probability at anthesis and 5 days after anthesis respectively, in the inferior spikelet and the fold change values of DGE matched with pattern of gene expression (relative transcript level) in the qRT-PCR studies conducted for relevant miRNAs and protein factors for ethylene and auxin signalling. In conclusion, epigenetic regulation of both auxin and ethylene homeostasis control grain filling of rice spikelet was established, but evidences were more robust for the latter.

Main Conclusion: Light, hormones and their interaction regulate different aspects of development in non-flowering plants. They might have played a role in the evolution of different plant groups by conferring specific adaptive evolutionary changes. Plants are sessile organisms. Unlike animals, they lack the opportunity to abandon their habitat in unfavorable conditions. They respond to different environmental cues and adapt accordingly to control their growth and developmental pattern. While phytohormones are known to be internal regulators of plant development, light is a major environmental signal that shapes plant processes. It is plausible that light-hormone crosstalk might have played an important role in plant evolution. But how the crosstalk between light and phytohormone signaling pathways might have shaped the plant evolution is unclear. One of the possible reasons is that flowering plants have been studied extensively in context of plant development, which cannot serve the purpose of evolutionary comparisons. In order to elucidate the role of light, hormone and their crosstalk in the evolutionary adaptation in plant kingdom, one needs to understand various light- and hormone-mediated processes in diverse non-flowering plants. This review is an attempt to outline major light- and phytohormone-mediated responses in non-flowering plant groups such as algae, bryophytes, pteridophytes and gymnosperms.

The Evening Complex (EC), composed of the DNA binding protein LUX ARRHYTHMO (LUX) and two additional proteins EARLY FLOWERING 3 (ELF3) and ELF4, is a transcriptional repressor complex and a core component of the plant circadian clock. In addition to maintaining oscillations in clock gene expression, the EC also participates in temperature and light entrainment, acting as an important environmental sensor and conveying this information to growth and developmental pathways. However, the molecular basis for EC DNA binding specificity and temperature-dependent activity were not known. Here, we solved the structure of the DNA binding domain of LUX in complex with DNA. Residues critical for high-affinity binding and direct base readout were determined and tested via site-directed mutagenesis in vitro and in vivo. Using extensive in vitro DNA binding assays of LUX alone and in complex with ELF3 and ELF4, we demonstrate that, while LUX alone binds DNA with high affinity, the LUX-ELF3 complex is a relatively poor binder of DNA. ELF4 restores binding to the complex. In vitro, the full EC is able to act as a direct thermosensor, with stronger DNA binding at 4 °C and weaker binding at 27 °C. In addition, an excess of ELF4 is able to restore EC binding even at 27 °C. Taken together, these data suggest that ELF4 is a key modulator of thermosensitive EC activity., Competing Interests: The authors declare no competing interest., (Copyright © 2020 the Author(s). Published by PNAS.)

This study reports the synthesis of an unprecedented bio-based aquasorbent guargum-g-hyperbranched poly (acrylic acid); bGG-g-HBPAA by employing graft-copolymerization and "Strathclyde methodology" simultaneously in emulsion and its possible use as a sustainable nutrient bed for the effective growth of Anabaena cylindrica and Vigna radiata seedlings. The formation of bGG-g-HBPAA and the presence of hyperbranched architectures was confirmed from XRD, FTIR, 13 C NMR, solubility, intrinsic viscosity, BET surface area/ pore size, SEM and rheology analyses. The synthesized grade with a branching percent of 65.4% and a swelling percentage of 13,300% facilitated maximum growth of the cultured species as compared to guargum and its linear graft. Semi synthetic bGG-g-HBPAA culture medium was optically transparent, dried at a controlled rate, held a huge amount of water for growth, provided sufficient space for unhindered growth and featured dimensional stability., (Copyright © 2019. Published by Elsevier Ltd.)

Mosses were proved as an ideal and reliable biomonitor as well as an indicator of atmospheric trace metal pollution. They are used as model indicator species of air pollution since long back due to their simple structure, genetic diversity, totipotency, rapid colony-forming ability, and high metal resistance behavior. Bryomonitoring technique is gradually being popularized as an economically viable procedure for estimating the degrees of environmental health and evaluating the toxic pollutants in biosphere. Thus, in the present scenario, many parts of the world use these organisms for monitoring the air pollution. This article describes an overview of the relationship of terrestrial mosses with trace metals with respect to their uptake, accumulation, and toxification as well as detoxification and tolerance mechanisms. The review article explicitly expresses the caliber of the cryptogamic mosses in establishing the pristine environment around the world. It also highlights the underpinning mechanisms and potential for future research directions. We have referred more than 250 articles, which deals with the assessment and impact of different heavy metals on 52 numbers of different moss species belongs to different climatic zones. The present review covers the research work in this area carried out worldwide since 1965.

Background: Root morphology is known to be affected by light quality, quantity and direction. Light signal is perceived at the shoot, translocated to roots through vasculature and further modulates the root development. Photoreceptors are differentially expressed in both shoot and root cells. The light irradiation to the root affects shoot morphology as well as whole plant development. The current work aims to understand the white light intensity dependent changes in root patterning and correlate that with the global gene expression profile., Results: Different fluence of white light (WL) regulate overall root development via modulating the expression of a specific set of genes. Phytochrome A deficient Arabidopsis thaliana (phyA-211) showed shorter primary root compared to phytochrome B deficient (phyB-9) and wild type (WT) seedlings at a lower light intensity. However, at higher intensity, both mutants showed shorter primary root in comparison to WT. The lateral root number was observed to be lowest in phyA-211 at intensities of 38 and 75 μmol m  -  2 s  -  1 . The number of adventitious roots was significantly lower in phyA-211 as compared to WT and phyB-9 under all light intensities tested. With the root phenotypic data, microarray was performed for four different intensities of WL light in WT. Here, we identified ~ 5243 differentially expressed genes (DEGs) under all light intensities. Gene ontology-based analysis indicated that different intensities of WL predominantly affect a subset of genes having catalytic activity and localized to the cytoplasm and membrane. Furthermore, when root is irradiated with different intensities of WL, several key genes involved in hormone, light signaling and clock-regulated pathways are differentially expressed., Conclusion: Using genome wide microarray-based approach, we have identified candidate genes in Arabidopsis root that responded to the changes in light intensities. Alteration in expression of genes such as PIF4, COL9, EPR1, CIP1, ARF18, ARR6, SAUR9, TOC1 etc. which are involved in light, hormone and clock pathway was validated by qRT-PCR. This indicates their potential role in light intensity mediated root development.

This study identifies characteristics of seedling, mature plant phenotypes, changes at genetic and genomic level associated with Swarnaprabha (SP) rice grown under prolonged shade and compared with Nagina 22 (N22). Coleoptile length under low red/far-red was intermediate between that in dark and red light in a 7-days growth frame. Whereas, highest rootlet number was discriminating in seedlings grown for 28 days in hydroponics. In shade, SP and N22 both showed several tolerant mature plant phenotypes, except the panicle length, yield per plant and % grain filling, which were higher in SP. Percentage decrease in yield / plant in shade showed significant positive correlation with increase in NDVI, decrease in panicle length and % grain filling (p ≤ 0.01). Rate of panicle emergence in shade was higher in SP than N22. Expression patterns of PHYTOCHROME INTERACTING FACTOR LIKE-13 and PHYTOCHROME B were contrasting in SP and N22 seedlings under continuous red or red/far-red. Microarray analysis revealed the up-regulation of most of the ethylene and cytokinin pathway genes in shade grown panicles of SP. Significant up-regulation of ETHYLENE RESPONSE ELEMENT BINDING PROTEIN-2, MOTHER OF FLOWERING TIME 1, and SHORT PANICLE1 genes in shade grown panicles of SP could explain its sustainable higher yield in shade.

Eco-friendly biosynthetic approach for silver nanoparticles production using plant extracts is an exciting advancement in bio-nanotechnology and has been successfully attempted in nearly 41 plant species. However, an established model plant system for systematically unraveling the biochemical components required for silver nanoparticles production is lacking. Here we used Arabidopsis thaliana as the model plant for silver nanoparticles biosynthesis in vitro . Employing biochemical, spectroscopic methods, selected mutants and over-expressor plants of Arabidopsis involved in pleotropic functions and sugar homeostasis, we show that carbohydrates, polyphenolics and glyco-proteins are essential components which stimulated silver nanoparticles synthesis. Using molecular genetics as a tool, our data enforces the requirement of sugar conjugated proteins as essentials for AgNPs synthesis over protein alone. Additionally, a comparative analysis of AgNPs synthesis using the aqueous extracts of some of the plant species found in a brackish water ecosystem (Gracilaria, Potamogeton, Enteromorpha and Scendesmus ) were explored. Plant extract of Potamogeton showed the highest potential of nanoparticles production comparable to that of Arabidopsis among the species tested. Silver nanoparticles production in the model plant Arabidopsis not only opens up a possibility of using molecular genetics tool to understand the biochemical pathways and components in detail for its synthesis.

Root development in plants is affected by light and phytohormones. Different ranges of light wavelength influence root patterning in a particular manner. Red and white light promote overall root development, whereas blue light has both positive as well as negative role in these processes. Light-mediated root development primarily occurs through modulation of synthesis, signaling and transport of the phytohormone auxin. Auxin has been shown to play a critical role in root development. It is being well-understood that components of light and auxin signaling cross-talk with each other. However, the signaling network that can modulate the root development is an intense area of research. Currently, limited information is available about the interaction of these two signaling pathways. This review not only summarizes the current findings on how different quality and quantity of light affect various aspects of root development but also present the role of auxin in these developmental aspects starting from lower to higher plants.

Key Message: Inclusion of carbon nanoparticles in growth medium accelerates timing to flower by down-regulating phytochrome B in a CONSTANS-independent but photoperiod-dependent manner in Arabidopsis thaliana. Despite the recognized importance of nanoparticles in plant development over the last decade, the effect of carbon nanoparticles (CNPs) on plant processes such as photomorphogenesis and flowering time control is poorly understood. We explored the uptake, accumulation and effect of CNPs on seedling development and flowering time control in Arabidopsis thaliana (At). CNPs uptake was demonstrated using Raman spectroscopy and light microscopy that affected At seedling growth and flowering time in a dose-dependent manner. The highest accumulation of CNPs was observed in leaves followed by stem and root tissues. CNPs treatment enhanced seed germination, showed elongated hypocotyl, larger cotyledon area and increased chlorophyll content in At seedlings. CNPs treatment induced early flowering in both long-day and short-day growth conditions indicating a photoperiod-dependent effect. CNPs-treated seedlings showed a drastic reduction in the relative abundance of phytochrome B (PHYB) transcript. Further, we analyzed the transcript abundance of at least one major component involved in various pathways that regulate flowering such as (1) photoperiod, (2) gibberellic acid (GA), (3) vernalization and (4) autonomous. An up-regulation of transcript levels of PHYTOCHROME INTERACTING FACTOR 4 (PIF4), GIGANTEA (GI), REPRESSOR OF GIBBERELLIC ACID 1 (RGA1) and LEAFY (LFY) were observed, however, there were no changes in the transcript levels of CONSTANS (CO), VERNALIZATION 1 (VRN1) and FLOWERING CONTROL LOCUS A (FCA). Despite the up-regulation of RGA1, we conclude that the earlier flowering is most likely GA-independent. Here, we demonstrated that the early flowering in CNPs-treated seedlings was PHYB and photoperiod-dependent.