The Molecular Regulatory Pathways and Metabolic Adaptation in the Seed Germination and Early Seedling Growth of Rice in Response to Low O2 Stress

As sessile organisms, flooding/submergence is one of the major abiotic stresses for higher plants, with deleterious effects on their growth and survival. Therefore, flooding/submergence is a large challenge for agriculture in lowland areas worldwide. Long-term flooding/submergence can cause severe hypoxia stress to crop plants and can result in substantial yield loss. Rice has evolved distinct adaptive strategies in response to low oxygen (O2) stress caused by flooding/submergence circumstances. Recently, direct seeding practice has been increasing in popularity due to its advantages of reducing cultivation cost and labor. However, establishment and growth of the seedlings from seed germination under the submergence condition are large obstacles for rice in direct seeding practice. The physiological and molecular regulatory mechanisms underlying tolerant and sensitive phenotypes in rice have been extensively investigated. Here, this review focuses on the progress of recent advances in the studies of the molecular mechanisms and metabolic adaptions underlying anaerobic germination (AG) and coleoptile elongation. Further, we highlight the prospect of introducing quantitative trait loci (QTL) for AG into rice mega varieties to ensure the compatibility of flooding/submergence tolerance traits and yield stability, thereby advancing the direct seeding practice and facilitating future breeding improvement.

Download Full-text

iTRAQ-Based Analysis of Proteins Co-Regulated by Brassinosteroids and Gibberellins in Rice Embryos during Seed Germination

International Journal of Molecular Sciences ◽

10.3390/ijms19113460 ◽

2018 ◽

Vol 19 (11) ◽

pp. 3460 ◽

Cited By ~ 4

Author(s):

Qian-Feng Li ◽

Jin-Dong Wang ◽

Min Xiong ◽

Ke Wei ◽

Peng Zhou ◽

...

Keyword(s):

Seed Germination ◽

Regulatory Network ◽

Regulatory Networks ◽

Molecular Mechanisms ◽

Higher Plants ◽

Absolute Quantification ◽

Rice Seed ◽

Differentially Expressed Proteins ◽

Search Tool ◽

Isobaric Tags

Seed germination, a pivotal process in higher plants, is precisely regulated by various external and internal stimuli, including brassinosteroid (BR) and gibberellin (GA) phytohormones. The molecular mechanisms of crosstalk between BRs and GAs in regulating plant growth are well established. However, whether BRs interact with GAs to coordinate seed germination remains unknown, as do their common downstream targets. In the present study, 45 differentially expressed proteins responding to both BR and GA deficiency were identified using isobaric tags for relative and absolute quantification (iTRAQ) proteomic analysis during seed germination. The results indicate that crosstalk between BRs and GAs participates in seed germination, at least in part, by modulating the same set of responsive proteins. Moreover, most targets exhibited concordant changes in response to BR and GA deficiency, and gene ontology (GO) indicated that most possess catalytic activity and are involved in various metabolic processes. Search Tool for the Retrieval of Interacting Genes/Proteins (STRING) analysis was used to construct a regulatory network of downstream proteins mediating BR- and GA-regulated seed germination. The mutation of GRP, one representative target, notably suppressed seed germination. Our findings not only provide critical clues for validating BR–GA crosstalk during rice seed germination, but also help to optimise molecular regulatory networks.

Download Full-text

Molecular Mechanisms Supporting Rice Germination and Coleoptile Elongation under Low Oxygen

Plants ◽

10.3390/plants9081037 ◽

2020 ◽

Vol 9 (8) ◽

pp. 1037 ◽

Cited By ~ 1

Author(s):

Chiara Pucciariello

Keyword(s):

Molecular Mechanisms ◽

Fermentable Sugar ◽

Low Oxygen ◽

Source To Sink ◽

Coleoptile Elongation

Rice germinates under submergence by exploiting the starch available in the endosperm and translocating sugars from source to sink organs. The availability of fermentable sugar under water allows germination with the protrusion of the coleoptile, which elongates rapidly and functions as a snorkel toward the air above. Depending on the variety, rice can produce a short or a long coleoptile. Longer length entails the involvement of a functional transport of auxin along the coleoptile. This paper is an overview of rice coleoptiles and the studies undertaken to understand its functioning and role under submergence.

Download Full-text

Oxidative signalling in seed germination and early seedling growth: an emerging role for ROS trafficking and inter-organelle communication

Biochemical Journal ◽

10.1042/bcj20200934 ◽

2021 ◽

Vol 478 (10) ◽

pp. 1977-1984

Author(s):

Christophe Bailly ◽

Livia Merendino

Keyword(s):

Seed Germination ◽

Higher Plants ◽

Seedling Emergence ◽

Future Directions ◽

Cell Compartments ◽

Ros Homeostasis ◽

Retrograde Signalling ◽

Early Seedling ◽

Organelle Communication

Underground early development of higher plants includes two distinct developmental processes, seed germination and then skotomorphogenesis, a mechanism which favours elongation of the hypocotyl and helps the seedling to find light. Interestingly, both processes, which are regulated by plant hormones, have been shown to depend on reactive oxygen species metabolism and to be related to mitochondrial retrograde signalling. Here we review the recent outcomes in this field of research and highlight the emerging role of ROS communication between organelles and cell compartments. We point out the role of mitochondria as an environmental and developmental sensor organelle that regulates ROS homeostasis and downstream events and we propose future directions of research that should help better understanding the roles of ROS in germination and seedling emergence.

Download Full-text

Hypoxia, Metabolic Reprogramming, and Drug Resistance in Liver Cancer

Cells ◽

10.3390/cells10071715 ◽

2021 ◽

Vol 10 (7) ◽

pp. 1715

Author(s):

Macus Hao-Ran Bao ◽

Carmen Chak-Lui Wong

Keyword(s):

Hepatocellular Carcinoma ◽

Drug Resistance ◽

Liver Cancer ◽

Effective Treatment ◽

Molecular Mechanisms ◽

Hypoxia Inducible Factor ◽

Metabolic Reprogramming ◽

Combination Therapies ◽

Low Oxygen ◽

Treatment Regimens

Hypoxia, low oxygen (O2) level, is a hallmark of solid cancers, especially hepatocellular carcinoma (HCC), one of the most common and fatal cancers worldwide. Hypoxia contributes to drug resistance in cancer through various molecular mechanisms. In this review, we particularly focus on the roles of hypoxia-inducible factor (HIF)-mediated metabolic reprogramming in drug resistance in HCC. Combination therapies targeting hypoxia-induced metabolic enzymes to overcome drug resistance will also be summarized. Acquisition of drug resistance is the major cause of unsatisfactory clinical outcomes of existing HCC treatments. Extra efforts to identify novel mechanisms to combat refractory hypoxic HCC are warranted for the development of more effective treatment regimens for HCC patients.

Download Full-text

SLC6A8-mediated intracellular creatine accumulation enhances hypoxic breast cancer cell survival via ameliorating oxidative stress

Journal of Experimental & Clinical Cancer Research ◽

10.1186/s13046-021-01933-7 ◽

2021 ◽

Vol 40 (1) ◽

Author(s):

Qiao Li ◽

Manran Liu ◽

Yan Sun ◽

Ting Jin ◽

Pengpeng Zhu ◽

...

Keyword(s):

Breast Cancer ◽

Overall Survival ◽

Molecular Mechanisms ◽

Expression Profiles ◽

Histological Grade ◽

Metabolic Adaptation ◽

Mitochondrial Activity ◽

Cell Viability Assay ◽

Ki 67 ◽

The Impact

Abstract Background Triple-negative breast cancer (TNBC) is the most aggressive subtype of breast cancer, with poor prognosis and limited treatment options. Hypoxia is a key hallmark of TNBC. Metabolic adaptation promotes progression of TNBC cells that are located within the hypoxic tumor regions. However, it is not well understood regarding the precise molecular mechanisms underlying the regulation of metabolic adaptions by hypoxia. Methods RNA sequencing was performed to analyze the gene expression profiles in MDA-MB-231 cell line (20% O2 and 1% O2). Expressions of Slc6a8, which encodes the creatine transporter protein, were detected in breast cancer cells and tissues by quantitative real-time PCR. Immunohistochemistry was performed to detect SLC6A8 protein abundances in tumor tissues. Clinicopathologic correlation and overall survival were evaluated by chi-square test and Kaplan-Meier analysis, respectively. Cell viability assay and flow cytometry analysis with Annexin V/PI double staining were performed to investigate the impact of SLC6A8-mediated uptake of creatine on viability of hypoxic TNBC cells. TNBC orthotopic mouse model was used to evaluate the effects of creatine in vivo. Results SLC6A8 was aberrantly upregulated in TNBC cells in hypoxia. SLC6A8 was drastically overexpressed in TNBC tissues and its level was tightly associated with advanced TNM stage, higher histological grade and worse overall survival of TNBC patients. We found that SLC6A8 was transcriptionally upregulated by p65/NF-κB and mediated accumulation of intracellular creatine in hypoxia. SLC6A8-mediated accumulation of creatine promoted survival and suppressed apoptosis via maintaining redox homeostasis in hypoxic TNBC cells. Furthermore, creatine was required to facilitate tumor growth in xenograft mouse models. Mechanistically, intracellular creatine bolstered cell antioxidant defense by reducing mitochondrial activity and oxygen consumption rates to reduce accumulation of intracellular reactive oxygen species, ultimately activating AKT-ERK signaling, the activation of which protected the viability of hypoxic TNBC cells via mediating the upregulation of Ki-67 and Bcl-2, and the downregulation of Bax and cleaved Caspase-3. Conclusions Our study indicates that SLC6A8-mediated creatine accumulation plays an important role in promoting TNBC progression, and may provide a potential therapeutic strategy option for treatment of SLC6A8 high expressed TNBC.

Download Full-text

The CBL-Interacting Protein Kinase NtCIPK23 Positively Regulates Seed Germination and Early Seedling Development in Tobacco (Nicotiana tabacum L.)

Plants ◽

10.3390/plants10020323 ◽

2021 ◽

Vol 10 (2) ◽

pp. 323

Author(s):

Sujuan Shi ◽

Lulu An ◽

Jingjing Mao ◽

Oluwaseun Olayemi Aluko ◽

Zia Ullah ◽

...

Keyword(s):

Protein Kinase ◽

Seed Germination ◽

Seedling Growth ◽

Hypocotyl Elongation ◽

Interacting Protein ◽

Knock Out ◽

Early Seedling Growth ◽

Tobacco Seedlings ◽

Early Seedling ◽

Cotyledon Expansion

CBL-interacting protein kinase (CIPK) family is a unique group of serine/threonine protein kinase family identified in plants. Among this family, AtCIPK23 and its homologs in some plants are taken as a notable group for their importance in ions transport and stress responses. However, there are limited reports on their roles in seedling growth and development, especially in Solanaceae plants. In this study, NtCIPK23, a homolog of AtCIPK23 was cloned from Nicotiana tabacum. Expression analysis showed that NtCIPK23 is mainly expressed in the radicle, hypocotyl, and cotyledons of young tobacco seedlings. The transcriptional level of NtCIPK23 changes rapidly and spatiotemporally during seed germination and early seedling growth. To study the biological function of NtCIPK23 at these stages, the overexpressing and CRISPR/Cas9-mediated knock-out (ntcipk23) tobacco lines were generated. Phenotype analysis indicated that knock-out of NtCIPK23 significantly delays seed germination and the appearance of green cotyledon of young tobacco seedling. Overexpression of NtCIPK23 promotes cotyledon expansion and hypocotyl elongation of young tobacco seedlings. The expression of NtCIPK23 in hypocotyl is strongly upregulated by darkness and inhibited under light, suggesting that a regulatory mechanism of light might underlie. Consistently, a more obvious difference in hypocotyl length among different tobacco materials was observed in the dark, compared to that under the light, indicating that the upregulation of NtCIPK23 contributes greatly to the hypocotyl elongation. Taken together, NtCIPK23 not only enhances tobacco seed germination, but also accelerate early seedling growth by promoting cotyledon greening rate, cotyledon expansion and hypocotyl elongation of young tobacco seedlings.

Download Full-text

Inter-species functional compatibility of the Theobroma cacao and Arabidopsis FT orthologs: 90 million years of functional conservation of meristem identity genes

BMC Plant Biology ◽

10.1186/s12870-021-02982-y ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

S. F. Prewitt ◽

A. Shalit-Kaneh ◽

S. N. Maximova ◽

M. J. Guiltinan

Keyword(s):

Gene Expression ◽

Tissue Culture ◽

Gene Family ◽

Flowering Time ◽

Molecular Mechanisms ◽

Regulatory Pathways ◽

Late Flowering ◽

Precocious Flowering ◽

Transition To Flowering

Abstract Background In angiosperms the transition to flowering is controlled by a complex set of interacting networks integrating a range of developmental, physiological, and environmental factors optimizing transition time for maximal reproductive efficiency. The molecular mechanisms comprising these networks have been partially characterized and include both transcriptional and post-transcriptional regulatory pathways. Florigen, encoded by FLOWERING LOCUS T (FT) orthologs, is a conserved central integrator of several flowering time regulatory pathways. To characterize the molecular mechanisms involved in controlling cacao flowering time, we have characterized a cacao candidate florigen gene, TcFLOWERING LOCUS T (TcFT). Understanding how this conserved flowering time regulator affects cacao plant’s transition to flowering could lead to strategies to accelerate cacao breeding. Results BLAST searches of cacao genome reference assemblies identified seven candidate members of the CENTRORADIALIS/TERMINAL FLOWER1/SELF PRUNING gene family including a single florigen candidate. cDNA encoding the predicted cacao florigen was cloned and functionally tested by transgenic genetic complementation in the Arabidopsis ft-10 mutant. Transgenic expression of the candidate TcFT cDNA in late flowering Arabidopsis ft-10 partially rescues the mutant to wild-type flowering time. Gene expression studies reveal that TcFT is spatially and temporally expressed in a manner similar to that found in Arabidopsis, specifically, TcFT mRNA is shown to be both developmentally and diurnally regulated in leaves and is most abundant in floral tissues. Finally, to test interspecies compatibility of florigens, we transformed cacao tissues with AtFT resulting in the remarkable formation of flowers in tissue culture. The morphology of these in vitro flowers is normal, and they produce pollen that germinates in vitro with high rates. Conclusion We have identified the cacao CETS gene family, central to developmental regulation in angiosperms. The role of the cacao’s single FT-like gene (TcFT) as a general regulator of determinate growth in cacao was demonstrated by functional complementation of Arabidopsis ft-10 late-flowering mutant and through gene expression analysis. In addition, overexpression of AtFT in cacao resulted in precocious flowering in cacao tissue culture demonstrating the highly conserved function of FT and the mechanisms controlling flowering in cacao.

Download Full-text

Hypoxic tumor microenvironment: Implications for cancer therapy

Experimental Biology and Medicine ◽

10.1177/1535370220934038 ◽

2020 ◽

Vol 245 (13) ◽

pp. 1073-1086

Author(s):

Sukanya Roy ◽

Subhashree Kumaravel ◽

Ankith Sharma ◽

Camille L Duran ◽

Kayla J Bayless ◽

...

Keyword(s):

Tumor Microenvironment ◽

Cancer Cells ◽

Metabolic Regulation ◽

Molecular Mechanisms ◽

Hypoxia Inducible Factor ◽

Tumor Vasculature ◽

Therapeutic Strategies ◽

Therapeutic Resistance ◽

Low Oxygen ◽

Cancer Types

Hypoxia or low oxygen concentration in tumor microenvironment has widespread effects ranging from altered angiogenesis and lymphangiogenesis, tumor metabolism, growth, and therapeutic resistance in different cancer types. A large number of these effects are mediated by the transcription factor hypoxia inducible factor 1⍺ (HIF-1⍺) which is activated by hypoxia. HIF1⍺ induces glycolytic genes and reduces mitochondrial respiration rate in hypoxic tumoral regions through modulation of various cells in tumor microenvironment like cancer-associated fibroblasts. Immune evasion driven by HIF-1⍺ further contributes to enhanced survival of cancer cells. By altering drug target expression, metabolic regulation, and oxygen consumption, hypoxia leads to enhanced growth and survival of cancer cells. Tumor cells in hypoxic conditions thus attain aggressive phenotypes and become resistant to chemo- and radio- therapies resulting in higher mortality. While a number of new therapeutic strategies have succeeded in targeting hypoxia, a significant improvement of these needs a more detailed understanding of the various effects and molecular mechanisms regulated by hypoxia and its effects on modulation of the tumor vasculature. This review focuses on the chief hypoxia-driven molecular mechanisms and their impact on therapeutic resistance in tumors that drive an aggressive phenotype. Impact statement Hypoxia contributes to tumor aggressiveness and promotes growth of many solid tumors that are often resistant to conventional therapies. In order to achieve successful therapeutic strategies targeting different cancer types, it is necessary to understand the molecular mechanisms and signaling pathways that are induced by hypoxia. Aberrant tumor vasculature and alterations in cellular metabolism and drug resistance due to hypoxia further confound this problem. This review focuses on the implications of hypoxia in an inflammatory TME and its impact on the signaling and metabolic pathways regulating growth and progression of cancer, along with changes in lymphangiogenic and angiogenic mechanisms. Finally, the overarching role of hypoxia in mediating therapeutic resistance in cancers is discussed.

Download Full-text