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1.
Current Advances in Molecular Mechanisms and Physiological Basis of Panicle Degeneration in Rice.
Ali, A, Xu, P, Riaz, A, Wu, X
International journal of molecular sciences. 2019;(7)
Abstract
Panicle degeneration, also known as panicle abortion, is a serious defect and causes heavy losses to reproductive yield in cereals. Several mutants have been reported to display the phenotype of spikelet abortion in rice. Recent findings have resulted in significant breakthroughs, but comprehensive understanding about the molecular pathways and physiological basis of panicle degeneration still remain a dilemma. In this review, we have summarized all the responsible genes and mechanisms underlying the panicle development with a special focus on degeneration. Here, we hypothesized a model by using knowledge and coherent logic in order to understand the molecular regulation of panicle degeneration. In addition to this, we included all the previous discoveries, schools of thoughts, ancient working theories, and crosstalk of phytohormones and provided new insights for future studies.
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2.
Plant Growth Enhancement, Disease Resistance, and Elemental Modulatory Effects of Plant Probiotic Endophytic Bacillus sp. Fcl1.
Jayakumar, A, Krishna, A, Mohan, M, Nair, IC, Radhakrishnan, EK
Probiotics and antimicrobial proteins. 2019;(2):526-534
Abstract
Endophytic bacteria have already been studied for their beneficial support to plants to manage both biotic and abiotic stress through an array of well-established mechanisms. They have either direct or indirect impact on mobilizing diverse nutrients and elements from soil to plants. However, detailed insight into the fine-tuning of plant elemental composition by associated microorganism is very limited. In this study, endophytic Bacillus Fcl1 characterized from the rhizome of Curcuma longa was found to have broad range of plant growth-promoting and biocontrol mechanisms. The organism was found to have indole acetic acid and 1-aminocyclopropane-1-carboxylate deaminase production properties along with nitrogen fixation. The Bacillus Fcl1 could also inhibit diverse phytopathogens as confirmed by dual culture and well diffusion. By LC-MS/MS analysis, chemical basis of its antifungal activity has been proved to be due to the production of iturin A and a blend of surfactin compounds. Moreover, the organism was found to induce both plant growth and disease resistance in vivo in model plant system. Because of these experimentally demonstrated multiple plant probiotic features, Bacillus Fcl1 was selected as a candidate organism to study its role in modulation of plant elemental composition. ICP-MS analysis of Bacillus Fcl1-treated plants provided insight into relation of bacterial interaction with elemental composition of plants.
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3.
24-Epibrassinolide application in plants: An implication for improving drought stress tolerance in plants.
Tanveer, M, Shahzad, B, Sharma, A, Khan, EA
Plant physiology and biochemistry : PPB. 2019;:295-303
Abstract
Drought stress is one of most dramatic abiotic stresses, reduces crop yield significantly. Application of hormones proved as an effective drought stress ameliorating approach. 24-Epibrassinolide (EBL), an active by-product from brassinolide biosynthesis increases drought stress tolerance in plants significantly. EBL application enhances plant growth and development under drought stress by acting as signalling compound in different physiological processes. This article discussed potential role of 24-epibrassinolide application and drought tolerance in plants. Briefly, EBL sustains or improves plant growth and yield by enhancing carbon assimilation rate, maintaining a balance between ROS and antioxidants and also plays important role in solute accumulation and water relations. Furthermore, we also compared different EBL application methods and concluded that seed priming and foliar application are more productive as compared with root application method. In conclusion, EBL is very impressive phyto-hormone, which can ameliorate drought stress induced detrimental effects in plants.
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4.
Strain- or Stress-Sensing in Mechanochemical Patterning by the Phytohormone Auxin.
Julien, JD, Pumir, A, Boudaoud, A
Bulletin of mathematical biology. 2019;(8):3342-3361
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Abstract
Both chemical and mechanical fields are known to play a major role in morphogenesis. In plants, the phytohormone auxin and its directional transport are essential for the formation of robust patterns of organs, such as flowers or leaves, known as phyllotactic patterns. The transport of auxin was recently shown to be affected by mechanical signals, and conversely, auxin accumulation in incipient organs affects the mechanical properties of the cells. The precise interaction between mechanical fields and auxin transport, however, is poorly understood. In particular, it is unknown whether transport is sensitive to the strain or to the stress exerted on a given cell. Here, we investigate the nature of this coupling with the help of theoretical models. Namely, we introduce the effects of either mechanical stress or mechanical strain in a model of auxin transport and compare the patterns predicted with available experimental results, in which the tissue is perturbed by ablations, chemical treatments, or genetic manipulations. We also study the robustness of the patterning mechanism to noise and investigate the effect of a shock that changes abruptly its parameters. Although the model predictions with the two different feedbacks are often indistinguishable, the strain feedback seems to better agree with some of the experiments. The computational modeling approach used here, which enables us to distinguish between several possible mechanical feedbacks, offers promising perspectives to elucidate the role of mechanics in tissue development, and may help providing insight into the underlying molecular mechanisms.
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Comparing and Contrasting the Multiple Roles of Butenolide Plant Growth Regulators: Strigolactones and Karrikins in Plant Development and Adaptation to Abiotic Stresses.
Yang, T, Lian, Y, Wang, C
International journal of molecular sciences. 2019;(24)
Abstract
Strigolactones (SLs) and karrikins (KARs) are both butenolide molecules that play essential roles in plant growth and development. SLs are phytohormones, with SLs having known functions within the plant they are produced in, while KARs are found in smoke emitted from burning plant matter and affect seeds and seedlings in areas of wildfire. It has been suggested that SL and KAR signaling may share similar mechanisms. The α/β hydrolases DWARF14 (D14) and KARRIKIN INSENSITIVE 2 (KAI2), which act as receptors of SL and KAR, respectively, both interact with the F-box protein MORE AXILLARY GROWTH 2 (MAX2) in order to target SUPPRESSOR OF MAX2 1 (SMAX1)-LIKE/D53 family members for degradation via the 26S proteasome. Recent reports suggest that SLs and/or KARs are also involved in regulating plant responses and adaptation to various abiotic stresses, particularly nutrient deficiency, drought, salinity, and chilling. There is also crosstalk with other hormone signaling pathways, including auxin, gibberellic acid (GA), abscisic acid (ABA), cytokinin (CK), and ethylene (ET), under normal and abiotic stress conditions. This review briefly covers the biosynthetic and signaling pathways of SLs and KARs, compares their functions in plant growth and development, and reviews the effects of any crosstalk between SLs or KARs and other plant hormones at various stages of plant development. We also focus on the distinct responses, adaptations, and regulatory mechanisms related to SLs and/or KARs in response to various abiotic stresses. The review closes with discussion on ways to gain additional insights into the SL and KAR pathways and the crosstalk between these related phytohormones.
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Spatio-temporal expression of phytoglobin: a determining factor in the NO specification of cell fate.
Stasolla, C, Huang, S, Hill, RD, Igamberdiev, AU
Journal of experimental botany. 2019;(17):4365-4377
Abstract
Plant growth and development rely on the orchestration of cell proliferation, differentiation, and ultimately death. After varying rounds of divisions, cells respond to positional cues by acquiring a specific fate and embarking upon distinct developmental pathways which might differ significantly from those of adjacent cells exposed to diverse cues. Differential cell behavior is most apparent in response to stress, when some cells might be more vulnerable than others to the same stress condition. This appears to be the case for stem cells which show abnormal features of differentiation and ultimately signs of deterioration at the onset of specific types of stress such as hypoxia and water deficit. A determining factor influencing cell behavior during growth and development, and cell response during conditions of stress is nitric oxide (NO), the level of which can be regulated by phytoglobins (Pgbs), known scavengers of NO. The modulation of NO by Pgbs can be cell, tissue, and/or organ specific, as revealed by the expression patterns of Pgbs dictated by the presence of distinct cis-regulatory elements in their promoters. This review discusses how the temporal and spatial Pgb expression pattern influences NO-mediated responses and ultimately cell fate acquisition in plant developmental processes.
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7.
The magic 'hammer' of TOR: the multiple faces of a single pathway in the metabolic regulation of plant growth and development.
Caldana, C, Martins, MCM, Mubeen, U, Urrea-Castellanos, R
Journal of experimental botany. 2019;(8):2217-2225
Abstract
The target of rapamycin (TOR) pathway has emerged as a central hub synchronizing plant growth according to the nutrient/energy status and environmental inputs. Molecular mechanisms through which TOR promotes plant growth involve the positive regulation of transcription of cell proliferation-associated genes, mRNA translation initiation and ribosome biogenesis, to cite a few examples. Phytohormones, light, sugars, and sulfur have been found to broadly regulate TOR activity. TOR operates as a metabolic homeostat to fine-tune anabolic processes and efficiently enable plant growth under different circumstances. However, little is known about the multiple effectors that act up- and downstream of TOR. Here, we mainly discuss recent findings related to the TOR pathway in the context of plant metabolism and highlight areas of interest that need to be addressed to keep unravelling the intricate networks governing the regulation of TOR and its function in controlling biosynthetic growth.
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Monkeyflowers (Mimulus): new model for plant developmental genetics and evo-devo.
Yuan, YW
The New phytologist. 2019;(2):694-700
Abstract
Contents Summary 694 I. Introduction 694 II. The system 695 III. Regulation of carotenoid pigmentation 695 IV. Formation of periodic pigmentation patterns 696 V. Developmental genetics of corolla tube formation and elaboration 697 VI. Molecular basis of floral trait variation underlying pollinator shift 698 VII. Outlook 699 Acknowledgements 699 References 699 SUMMARY Monkeyflowers (Mimulus) have long been recognized as a classic ecological and evolutionary model system. However, only recently has it been realized that this system also holds great promise for studying the developmental genetics and evo-devo of important plant traits that are not found in well-established model systems such as Arabidopsis. Here, I review recent progress in four different areas of plant research enabled by this new model, including transcriptional regulation of carotenoid biosynthesis, formation of periodic pigmentation patterns, developmental genetics of corolla tube formation and elaboration, and the molecular basis of floral trait divergence underlying pollinator shift. These examples suggest that Mimulus offers ample opportunities to make exciting discoveries in plant development and evolution.
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9.
Effect of ionizing radiation on physiological and molecular processes in plants.
Gudkov, SV, Grinberg, MA, Sukhov, V, Vodeneev, V
Journal of environmental radioactivity. 2019;:8-24
Abstract
The study of effects of ionizing radiation (IR) on plants is important in relation to several problems: (I) the existence of zones where background radiation - either natural or technogenic - is increased; (II) the problems of space biology; (III) the use of IR in agricultural selection; (IV) general biological problems related to the fundamental patterns and specifics of the effects of IR on various living organisms. By now, researchers have accumulated and systematized a large body of data on the effects of IR on the growth and reproduction of plants, as well as on the changes induced by IR at the genetic level. At the same time, there is a large gap in understanding the mechanisms of IR influence on the biochemical and physiological processes - despite the fact that these processes form the basis determining the manifestation of IR effects at the level of the whole organism. On the one hand, the activity of physiological processes determines the growth of plants; on the other, it is determined by changes at the genetic level. Thus, it is the study of IR effects at the physiological and biochemical levels that can give the most detailed and complex picture of IR action in plants. The review focuses on the effects of radiation on the essential physiological processes, including photosynthesis, respiration, long-distance transport, the functioning of the hormonal system, and various biosynthetic processes. On the basis of a large body of experimental data, we analyze dose and time dependences of the IR-induced effects - which are qualitatively similar - on various physiological and biochemical processes. We also consider the sequence of stages in the development of those effects and discuss their mechanisms, as well as the cause-effect relationships between them. The primary IR-induced physicochemical reactions include the formation of various forms of reactive oxygen species (ROS) and are the cause of the observed changes in the functional activity of plants. The review emphasizes the role of hydrogen peroxide, a long-lived ROS, not only as a damaging agent, but also as a mediator - a universal intracellular messenger, which provides for the mechanism of long-distance signaling. A supposition is made that IR affects physiological processes mainly by violating the regulation of their activity. The violation seems to become possible due to the fact that there exists a crosstalk between different signaling systems of plants, such as ROS, calcium, hormonal and electrical systems. As a result of both acute and chronic irradiation, an increase in the level of ROS can influence the activity of a wide range of physiological processes - by regulating them both at the genetic and physiological levels. To understand the ways, by which IR affects plant growth and development, one needs detailed knowledge about the mechanisms of the processes that occur at the (i) genetic and (ii) physiological levels, as well as their interplay and (iii) knowledge about regulation of these processes at different levels.
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10.
Integration of nutrient, energy, light, and hormone signalling via TOR in plants.
Wu, Y, Shi, L, Li, L, Fu, L, Liu, Y, Xiong, Y, Sheen, J
Journal of experimental botany. 2019;(8):2227-2238
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Abstract
The multidomain target of rapamycin (TOR) is an atypical serine/threonine protein kinase resembling phosphatidylinositol lipid kinases, but retains high sequence identity and serves a remarkably conserved role as a master signalling integrator in yeasts, plants, and humans. TOR dynamically orchestrates cell metabolism, biogenesis, organ growth, and development transitions in response to nutrient, energy, hormone, and environmental cues. Here we review recent findings on the versatile and complex roles of TOR in transcriptome reprogramming, seedling, root, and shoot growth, and root hair production activated by sugar and energy signalling. We explore how co-ordination of TOR-mediated light and hormone signalling is involved in root and shoot apical meristem activation, proliferation of leaf primordia, cotyledon/leaf greening, and hypocotyl elongation. We also discuss the emerging TOR functions in response to sulfur assimilation and metabolism and consider potential molecular links and positive feedback loops between TOR, sugar, energy, and other essential macronutrients.