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New insights into gibberellin signaling in regulating flowering in Arabidopsis.
Bao, S, Hua, C, Shen, L, Yu, H
Journal of integrative plant biology. 2020;(1):118-131
Abstract
In angiosperms, floral transition is a key developmental transition from the vegetative to reproductive growth, and requires precise regulation to maximize the reproductive success. A complex regulatory network governs this transition through integrating flowering pathways in response to multiple exogenous and endogenous cues. Phytohormones are essential for proper plant developmental regulation and have been extensively studied for their involvement in the floral transition. Among various phytohormones, gibberellin (GA) plays a major role in affecting flowering in the model plant Arabidopsis thaliana. The GA pathway interact with other flowering genetic pathways and phytohormone signaling pathways through either DELLA proteins or mediating GA homeostasis. In this review, we summarize the recent advances in understanding the mechanisms of DELLA-mediated GA pathway in flowering time control in Arabidopsis, and discuss its possible link with other phytohormone pathways during the floral transition.
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2.
Auxin-Abscisic Acid Interactions in Plant Growth and Development.
Emenecker, RJ, Strader, LC
Biomolecules. 2020;(2)
Abstract
Plant hormones regulate many aspects of plant growth, development, and response to biotic and abiotic stress. Much research has gone into our understanding of individual plant hormones, focusing primarily on their mechanisms of action and the processes that they regulate. However, recent research has begun to focus on a more complex problem; how various plant hormones work together to regulate growth and developmental processes. In this review, we focus on two phytohormones, abscisic acid (ABA) and auxin. We begin with brief overviews of the hormones individually, followed by in depth analyses of interactions between auxin and ABA, focusing on interactions in individual tissues and how these interactions are occurring where possible. Finally, we end with a brief discussion and future prospects for the field.
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3.
Nitrogen-phosphorus interplay: old story with molecular tale.
Hu, B, Chu, C
The New phytologist. 2020;(4):1455-1460
Abstract
Nitrogen (N) and phosphorus (P) are the two most abundant mineral nutrients used by plants, and are also the mostly widely used fertilizer elements driving crop yield improvement in agricultural production. The coordinated utilization of N and P is essential to maintain optimal plant growth and achieve maximal crop yield. The signaling pathways of N and P are generally studied separately, so our understanding of N-P interactions is very limited. A series of recent studies have revealed the critical components regulating N-P interactions in both Arabidopsis thaliana and rice (Oryza sativa), and have shed light on our in-depth understanding of the network integrating N and P signaling pathways. Here, we summarize recent progress on N-P interaction and propose possible working mechanisms integrating these N-P interactive regulation pathways. We further discuss future work that might reveal the N-P interactive regulation network in plants.
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4.
Mechanisms regulating PIF transcription factor activity at the protein level.
Favero, DS
Physiologia plantarum. 2020;(3):325-335
Abstract
Plant growth and development are precisely regulated by transcription factors (TFs) such as the PHYTOCHROME INTERACTING FACTORs (PIFs). PIFs regulate growth in response to various internal and external stimuli, and, accordingly, are regulated by a variety of different factors and mechanisms. Canonically, PIF activity is inhibited by light through the sequential phosphorylation, ubiquitination and degradation of these TFs in a manner dependent on their interaction with active phytochrome photoreceptors. However, work in more recent years has revealed that phytochromes also antagonize PIF activity by inhibiting their ability to bind DNA and, at least in the case of PIF7, by causing it to be retained in the cytoplasm. Recent work has also revealed specific kinases, phosphatases and E3 ubiquitin ligases which alter PIFs at the post-translational level. In a few cases, these studies have gone as far as identifying potential kinases responsible for phosphorylating PIFs in response to light. Moreover, additional factors have been identified that positively or negatively affect PIF binding to DNA or bind directly to PIF-DNA complexes and affect the transcriptional activation of target genes by these TFs. This review summarizes the variety of different mechanisms involved in PIF regulation and discusses some of the major unanswered questions in this area of research.
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5.
Regulation of auxin transcriptional responses.
Powers, SK, Strader, LC
Developmental dynamics : an official publication of the American Association of Anatomists. 2020;(4):483-495
Abstract
The plant hormone auxin acts as a signaling molecule to regulate a vast number of developmental responses throughout all stages of plant growth. Tight control and coordination of auxin signaling is required for the generation of specific auxin-response outputs. The nuclear auxin signaling pathway controls auxin-responsive gene transcription through the TRANSPORT INHIBITOR RESPONSE1/AUXIN SIGNALING F-BOX pathway. Recent work has uncovered important details into how regulation of auxin signaling components can generate unique and specific responses to determine auxin outputs. In this review, we discuss what is known about the core auxin signaling components and explore mechanisms important for regulating auxin response specificity.
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6.
D-amino Acids in Plants: Sources, Metabolism, and Functions.
Kolukisaoglu, Ü
International journal of molecular sciences. 2020;(15)
Abstract
Although plants are permanently exposed to D-amino acids (D-AAs) in the rhizosphere, these compounds were for a long time regarded as generally detrimental, due to their inhibitory effects on plant growth. Recent studies showed that this statement needs a critical revision. There were several reports of active uptake by and transport of D-AAs in plants, leading to the question whether these processes happened just as side reactions or even on purpose. The identification and characterization of various transporter proteins and enzymes in plants with considerable affinities or specificities for D-AAs also pointed in the direction of their targeted uptake and utilization. This attracted more interest, as D-AAs were shown to be involved in different physiological processes in plants. Especially, the recent characterization of D-AA stimulated ethylene production in Arabidopsis thaliana revealed for the first time a physiological function for a specific D-AA and its metabolizing enzyme in plants. This finding opened the question regarding the physiological or developmental contexts in which D-AA stimulated ethylene synthesis are involved in. This question and the ones about the transport characteristics of D-AAs, their metabolism, and their different physiological effects, are the focus of this review.
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7.
Towards an understanding of plant reproductive isolation: uncovering the species-specific signal for pollen tube guidance.
Gao, XQ, Guan, H, Zhang, XS
Science China. Life sciences. 2020;(4):620-622
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8.
Family plot: the impact of the endosperm and other extra-embryonic seed tissues on angiosperm zygotic embryogenesis.
Ingram, GC
F1000Research. 2020
Abstract
The zygotic embryos of angiosperms develop buried deep within seeds and surrounded by two main extra-embryonic tissues: the maternally derived seed coat tissues and the zygotic endosperm. Generally, these tissues are considered to play an important role in nurturing the developing embryo by acting as conduits for maternally derived nutrients. They are also critical for key seed traits (dormancy establishment and control, longevity, and physical resistance) and thus for seed and seedling survival. However, recent studies have highlighted the fact that extra-embryonic tissues in the seed also physically and metabolically limit embryonic development and that unique mechanisms may have evolved to overcome specific developmental and genetic constraints associated with the seed habit in angiosperms. The aim of this review is to illustrate how these studies have begun to reveal the highly complex physical and physiological relationship between extra-embryonic tissues and the developing embryo. Where possible I focus on Arabidopsis because of space constraints, but other systems will be cited where relevant.
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9.
Human and Arabidopsis alpha-ketoglutarate-dependent dioxygenase homolog proteins-New players in important regulatory processes.
Marcinkowski, M, Pilžys, T, Garbicz, D, Steciuk, J, Zugaj, D, Mielecki, D, Sarnowski, TJ, Grzesiuk, E
IUBMB life. 2020;(6):1126-1144
Abstract
The family of AlkB homolog (ALKBH) proteins, the homologs of Escherichia coli AlkB 2-oxoglutarate (2OG), and Fe(II)-dependent dioxygenase are involved in a number of important regulatory processes in eukaryotic cells including repair of alkylation lesions in DNA, RNA, and nucleoprotein complexes. There are nine human and thirteen Arabidopsis thaliana ALKBH proteins described, which exhibit diversified functions. Among them, human ALKBH5 and FaT mass and Obesity-associated (FTO) protein and Arabidopsis ALKBH9B and ALKBH10B have been recognized as N6 methyladenine (N6 meA) demethylases, the most abundant posttranscriptional modification in mRNA. The FTO protein is reported to be associated with obesity and type 2 diabetes, and involved in multiple other processes, while ALKBH5 is induced by hypoxia. Arabidopsis ALKBH9B is an N6 meA demethylase influencing plant susceptibility to viral infections via m6 A/A ratio control in viral RNA. ALKBH10B has been discovered to be a functional Arabidopsis homolog of FTO; thus, it is also an RNA N6 meA demethylase involved in plant flowering and several other regulatory processes including control of metabolism. High-throughput mass spectrometry showed multiple sites of human ALKBH phosphorylation. In the case of FTO, the type of modified residue decides about the further processing of the protein. This modification may result in subsequent protein ubiquitination and proteolysis, or in the blocking of these processes. However, the impact of phosphorylation on the other ALKBH function and their downstream pathways remains nearly unexplored in both human and Arabidopsis. Therefore, the investigation of evolutionarily conserved functions of ALKBH proteins and their regulatory impact on important cellular processes is clearly called for.
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10.
RNA-directed DNA Methylation and sexual reproduction: expanding beyond the seed.
Chow, HT, Chakraborty, T, Mosher, RA
Current opinion in plant biology. 2020;:11-17
Abstract
Two trends are changing our understanding of RNA-directed DNA methylation. In model systems like Arabidopsis, tissue-specific analysis of DNA methylation is uncovering dynamic changes in methylation during sexual reproduction and unraveling the contribution of maternal and paternal epigenomes to the developing embryo. These studies indicate that RNA-directed DNA Methylation might be important for mediating balance between maternal and paternal contributions to the endosperm. At the same time, researchers are moving beyond Arabidopsis to illuminate the ancestral role of RdDM in non-flowering plants that lack an endosperm, suggesting that RdDM might play a broader role in sexual reproduction.