scholarly journals Integrated Framework of the Immune-Defense Transcriptional Signatures in the Arabidopsis Shoot Apical Meristem

2020 ◽  
Vol 21 (16) ◽  
pp. 5745
Author(s):  
Muhammad Naseem ◽  
Özge Osmanoğlu ◽  
Martin Kaltdorf ◽  
Afnan Ali M. A. Alblooshi ◽  
Jibran Iqbal ◽  
...  
Keyword(s):  
Stem Cells ◽  
Immune Responses ◽  
Shoot Apical Meristem ◽  
Apical Meristem ◽  
Large Scale ◽  
Gene Expression Omnibus ◽  
Immune Defense ◽  
Immune Functions ◽  
Pathogen Infection ◽  
Immune Genes

The growing tips of plants grow sterile; therefore, disease-free plants can be generated from them. How plants safeguard growing apices from pathogen infection is still a mystery. The shoot apical meristem (SAM) is one of the three stem cells niches that give rise to the above ground plant organs. This is very well explored; however, how signaling networks orchestrate immune responses against pathogen infections in the SAM remains unclear. To reconstruct a transcriptional framework of the differentially expressed genes (DEGs) pertaining to various SAM cellular populations, we acquired large-scale transcriptome datasets from the public repository Gene Expression Omnibus (GEO). We identify here distinct sets of genes for various SAM cellular populations that are enriched in immune functions, such as immune defense, pathogen infection, biotic stress, and response to salicylic acid and jasmonic acid and their biosynthetic pathways in the SAM. We further linked those immune genes to their respective proteins and identify interactions among them by mapping a transcriptome-guided SAM-interactome. Furthermore, we compared stem-cells regulated transcriptome with innate immune responses in plants showing transcriptional separation among their DEGs in Arabidopsis. Besides unleashing a repertoire of immune-related genes in the SAM, our analysis provides a SAM-interactome that will help the community in designing functional experiments to study the specific defense dynamics of the SAM-cellular populations. Moreover, our study promotes the essence of large-scale omics data re-analysis, allowing a fresh look at the SAM-cellular transcriptome repurposing data-sets for new questions.

Combined SHOOT MERISTEMLESS and WUSCHEL trigger ectopic organogenesis inArabidopsis

Development ◽  
2002 ◽  
Vol 129 (13) ◽  
pp. 3207-3217 ◽  
Author(s):  
Jean-Luc Gallois ◽  
Claire Woodward ◽  
G. Venugopala Reddy ◽  
Robert Sablowski
Keyword(s):  
Stem Cells ◽  
Cell Division ◽  
Shoot Apical Meristem ◽  
Apical Meristem ◽  
Aerial Parts ◽  
Undifferentiated Cells ◽  
Activate Cell ◽  
Almost All ◽  
Differentiation Pathways ◽  
Shoot Meristemless

Almost all aerial parts of plants are continuously generated at the shoot apical meristem (SAM). To maintain a steady pool of undifferentiated cells in the SAM while continuously generating new organs, it is necessary to balance the rate of cell division with the rate of entrance into differentiation pathways. In the Arabidopsis meristem, SHOOT MERISTEMLESS (STM) and WUSCHEL (WUS) are necessary to keep cells undifferentiated and dividing. Here, we tested whether ectopic STM and WUS functions are sufficient to revert differentiation and activate cell division in differentiating tissues. Ectopic STM and WUS functions interacted non-additively and activated a subset of meristem functions, including cell division, CLAVATA1 expression and organogenesis, but not correct phyllotaxy or meristem self-maintenance. Our results suggest that WUS produces a non-cell autonomous signal that activates cell division in combination with STM and that combined WUS/STM functions can initiate the progression from stem cells to organ initiation.

scholarly journals Probing the Unknowns in Cytokinin-Mediated Immune Defense in Arabidopsis with Systems Biology Approaches

2014 ◽  
Vol 8 ◽  
pp. BBI.S13462 ◽  
Author(s):  
Muhammad Naseem ◽  
Meik Kunz ◽  
Thomas Dandekar
Keyword(s):  
Systems Biology ◽  
Immune Responses ◽  
Protein Interactions ◽  
Immune Defense ◽  
Immune Functions ◽  
Protein Protein Interactions ◽  
Cytokinin Signaling ◽  
Host Immune Responses ◽  
Arabidopsis Protein ◽  
Underlying Mechanisms

Plant hormones involving salicylic acid (SA), jasmonic acid (JA), ethylene (Et), and auxin, gibberellins, and abscisic acid (ABA) are known to regulate host immune responses. However, plant hormone cytokinin has the potential to modulate defense signaling including SA and JA. It promotes plant pathogen and herbivore resistance; underlying mechanisms are still unknown. Using systems biology approaches, we unravel hub points of immune interaction mediated by cytokinin signaling in Arabidopsis. High-confidence Arabidopsis protein—protein interactions (PPI) are coupled to changes in cytokinin-mediated gene expression. Nodes of the cellular interactome that are enriched in immune functions also reconstitute sub-networks. Topological analyses and their specific immunological relevance lead to the identification of functional hubs in cellular interactome. We discuss our identified immune hubs in light of an emerging model of cytokinin-mediated immune defense against pathogen infection in plants.

Flower meristem maintenance by TILLERS ABSENT 1 is essential for ovule development in rice

Development ◽  
2021 ◽  
Vol 148 (24) ◽  
Author(s):  
Wakana Tanaka ◽  
Suzuha Ohmori ◽  
Naoto Kawakami ◽  
Hiro-Yuki Hirano
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Flower Development ◽  
Shoot Apical Meristem ◽  
Apical Meristem ◽  
Stem Cell Marker ◽  
Ovule Development ◽  
Flower Meristem ◽  
Ovule Formation ◽  
Meristem Maintenance

ABSTRACT Plant development depends on the activity of pluripotent stem cells in meristems, such as the shoot apical meristem and the flower meristem. In Arabidopsis thaliana, WUSCHEL (WUS) is essential for stem cell homeostasis in meristems and integument differentiation in ovule development. In rice (Oryza sativa), the WUS ortholog TILLERS ABSENT 1 (TAB1) promotes stem cell fate in axillary meristem development, but its function is unrelated to shoot apical meristem maintenance in vegetative development. In this study, we examined the role of TAB1 in flower development. The ovule, which originates directly from the flower meristem, failed to differentiate in tab1 mutants, suggesting that TAB1 is required for ovule formation. Expression of a stem cell marker was completely absent in the flower meristem at the ovule initiation stage, indicating that TAB1 is essential for stem cell maintenance in the ‘final’ flower meristem. The ovule defect in tab1 was partially rescued by floral organ number 2 mutation, which causes overproliferation of stem cells. Collectively, it is likely that TAB1 promotes ovule formation by maintaining stem cells at a later stage of flower development.

scholarly journals DnaJ Proteins Regulate WUS Expression in Shoot Apical Meristem of Arabidopsis

Plants ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 136
Author(s):  
Tianqi Jia ◽  
Fan Li ◽  
Shuang Liu ◽  
Jin Dou ◽  
Tao Huang
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Environmental Factors ◽  
Transcriptional Activation ◽  
Shoot Apical Meristem ◽  
Apical Meristem ◽  
Cell Function ◽  
Self Regulation ◽  
The Self ◽  
Wus Gene

WUSCHEL (WUS) protein regulates stem cell function in shoot apical meristem of Arabidopsis. The expression of WUS gene is strictly regulated by developmental cues and environmental factors. As DnaJ domain-containing proteins, SDJ1 and SDJ3 have been proven to play an important role in transcriptional activation of promoter methylated genes. Here, we showed that three DnaJ domain-containing proteins including SDJ1 and SDJ3 can bind WUS protein as a complex, which further maintain the expression of WUS gene by binding to WUS promoter. We propose a model how DnaJ domain-containing proteins are involved in the self-regulation of WUS gene in stem cells maintenance of Arabidopsis.

TheWUSCHELandSHOOTMERISTEMLESSgenes fulfil complementary roles inArabidopsisshoot meristem regulation

Development ◽  
2002 ◽  
Vol 129 (13) ◽  
pp. 3195-3206 ◽  
Author(s):  
Michael Lenhard ◽  
Gerd Jürgens ◽  
Thomas Laux
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Cell Division ◽  
Pluripotent Stem Cells ◽  
Shoot Apical Meristem ◽  
Apical Meristem ◽  
Target Genes ◽  
Cell Specification ◽  
Downstream Target ◽  
Daughter Cells

Continuous organ formation from the shoot apical meristem requires the integration of two functions: a set of undifferentiated, pluripotent stem cells is maintained at the very tip of the meristem, while their daughter cells in the periphery initiate organ primordia. The homeobox genes WUSCHEL (WUS) and SHOOTMERISTEMLESS (STM) encode two major regulators of meristem formation and maintenance in Arabidopsis, yet their interaction in meristem regulation is presently unclear. Here, we have addressed this question using loss- and gain-of-function approaches. We show that stem cell specification by WUS does not require STM activity. Conversely, STM suppresses differentiation independently of WUS and is required and sufficient to promote cell division. Consistent with their independent and distinct phenotypic effects, ectopic WUS and STM activities induce the expression of different downstream target genes. Finally, the pathways regulated by WUS and STM appear to converge in the suppression of differentiation, since coexpression of both genes produced a synergistic effect, and increased WUS activity could partly compensate for loss of STM function. These results suggest that WUS and STM share labour in the shoot apical meristem: WUS specifies a subset of cells in the centre as stem cells, while STM is required to suppress differentiation throughout the meristem dome, thus allowing stem cell daughters to be amplified before they are incorporated into organs.

scholarly journals Infection risk and extensive parental care govern the molecular evolution of Toll-like receptors in birds

2019 ◽  
Author(s):  
Zhechun Zhang ◽  
Dan Liang ◽  
Guoling Chen ◽  
Fasheng Zou ◽  
Fumin Lei ◽  
...  
Keyword(s):  
Immune Responses ◽  
Parental Care ◽  
Positive Selection ◽  
Large Body ◽  
Bird Species ◽  
Infection Risk ◽  
Immune Functions ◽  
Long Distance ◽  
Immune Genes ◽  
Vital Functions

SummaryThe arms race between pathogens and the immune system of their hosts is a critical evolutionary force that affects the ecology and life history of organisms. An increased infection risk selects for adaptations in immune genes that encode receptors involved in pathogen recognition and the initiation of innate immune responses, including Toll-like receptor (TLR) genes. Although recent studies assessed the evolution of major histocompatibility complex (MHC) genes, the ecological and evolutionary processes that drive the evolution of immune genes across major phylogenetic lineages remain unstudied. Moreover, trade-offs between immune responses and other energy-demanding vital functions may limit the resource allocation into costly immune functions, and therefore affect the evolution of immune genes. Here we assess the evolutionary patterns of six TLR genes across 121 bird species, covering 95% of extant orders that represent diverse ecologies and life histories. Selection analyses revealed that all six TLR genes show strong signs of purifying selection, while few sites underwent episodic positive selection. Comparative phylogenetic analyses showed that the intensity of positive selection of TLR genes is associated with long-distance migration, extensive parental care (i.e., altricality and prolonged parent-offspring association), and a large body size (a proxy of increased longevity). Together, these results suggest that the evolution of immune genes is characterized by episodic positive selection, and is shaped by an increased inflection risk and extensive parental care that buffers the costs of immune functions.

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