Faberxu5074

In two-step culture systems for efficient shoot regeneration, explants are first cultured on auxin-rich callus-inducing medium (CIM), where cells are activated to proliferate and form calli containing root-apical meristem (RAM)-type stem cells and stem cell niche, and then cultured on cytokinin-rich shoot-inducing medium (SIM), where stem cells and stem cell niche of the shoot apical meristem (SAM) are established eventually leading to shoot regeneration. In the present study, we examined the effects of inhibitors of auxin biosynthesis and polar transport in the two-step shoot regeneration culture of Arabidopsis and found that, when they were applied during CIM culture, although callus growth was repressed, shoot regeneration in the subsequent SIM culture was significantly increased. The regeneration-stimulating effect of the auxin biosynthesis inhibitor was not linked with the reduction in the endogenous indole-3-acetic acid (IAA) level. Expression of the auxin-responsive reporter indicated that auxin response was more uniform and even stronger in the explants cultured on CIM with the inhibitors than in the control explants. These results suggested that the shoot regeneration competence of calli was enhanced somehow by the perturbation of the endogenous auxin dynamics, which we discuss in terms of the transformability between RAM and SAM stem cell niches.Multicellular organisms regulate cell numbers and cell fate by using asymmetric cell division (ACD) and symmetric cell division (SCD) during their development and to adapt to unfavorable environmental conditions. A stem cell self-renews and generates differentiated cells. In plants, various types of cells are produced by ACD or SCD; however, the molecular mechanisms of ACD or SCD and the cell division mode switch are largely unknown. The moss Physcomitrium (Physcomitrella) patens is a suitable model to study plant stem cells due to its simple anatomy. Here, we report the cell division mode switch induced by abscisic acid (ABA) in P. patens. ABA is synthesized in response to abiotic stresses and induces round-shape cells, called brood cells, from cylindrical protonemal cells. Although two daughter cells with distinct sizes were produced by ACD in a protonemal stem cell on ABA-free media, the sizes of two daughter cells became similar with ABA treatment. Actin microfilaments were spatially localized on the apices of apical stem cells in protonemata on ABA-free media, but the polar accumulation was lost under the condition of ABA treatment. Moreover, ABA treatment conferred an identical cell fate to the daughter cells in terms of cell division activity. Collectively, the results indicate ABA may suppress the ACD characteristics but evoke SCD in cells. We also noticed that ABA-induced brood cells not only self-renewed but regenerated protonemal cells when ABA was removed from the media, suggesting that brood cells are novel stem cells that are induced by environmental signals in P. patens.Plants precisely coordinate the balance between cell proliferation and differentiation to ensure the continuous development. In Arabidopsis thaliana, members of glycogen synthase kinase 3 (GSK3) family, which are highly conserved serine/threonine protein kinases among eukaryotes, play important roles in regulating cell proliferation and differentiation during various developmental processes. However, functional roles of GSK3s in the plant lineages except angiosperms remain to be elucidated. Here, we utilized a model liverwort, Marchantia polymorpha, for studies of GSK3, because it has a single GSK3-like kinase, MpGSK. When M. polymorpha was treated with a chemical compound, bikinin, which is known as a specific inhibitor for GSK3-like kinases, growth and morphologies were altered with an expansion of the meristematic region. Similarly, Mpgsk loss-of-function mutants accumulated undifferentiated cell mass with no differentiated tissues. By contrast, overexpression of MpGSK reduced the size of the meristem region. These results suggest that MpGSK plays important roles as a regulator for the balance between cell differentiation and proliferation in M. polymorpha.During embryogenesis of eudicots, the apical region of the embryo develops two cotyledon primordia and the shoot meristem. In Arabidopsis thaliana, this process is dependent on the functionally redundant activities of the CUP-SHAPED COTYLEDON (CUC) transcription factors, namely CUC1, CUC2, and CUC3, as well as the phytohormone auxin. However, the relationship between the CUC proteins and auxin has yet to be fully elucidated. In the present study, we examined whether the expression of auxin biosynthetic genes is dependent on CUC gene activities. Comprehensive quantitative RT-PCR analysis of the main auxin biosynthetic gene families of TRYPTOPHAN AMINOTRANSFERASE OF ARABIDOPSIS1/TRYPTOPHAN AMINOTRANSFERASE RELATED and YUCCA (YUC) showed that YUC1 and YUC4 expression levels were lower in cuc double mutant embryos than the expression levels of these genes in wild type embryos. Reporter analysis also revealed that the expression of YUC1 and YUC4 in the cotyledon boundary region was reduced in cuc double mutant embryos. In contrast, the loss of function mutation in the SHOOT MERISTEMLESS gene, a shoot stem cell regulator that acts downstream of the CUC genes, did not markedly affect YUC1 expression levels. These results demonstrate that CUC genes play an important role in the regulation of auxin biosynthetic gene expression during embryogenesis; furthermore, they raise the possibility that the auxin produced by this regulation contributes to cotyledon boundary development.For permanent secondary growth in plants, cell proliferation and differentiation should be strictly controlled in the vascular meristem consisting of (pro)cambial cells. A peptide hormone tracheary element differentiation inhibitory factor (TDIF) functions to inhibit xylem differentiation, while a plant hormone brassinosteroid (BR) promotes xylem differentiation in (pro)cambial cells. However, it remains unclear how TDIF and BR cooperate to regulate xylem differentiation for the proper maintenance of the vascular meristem. In this study, I developed an easy evaluation method for xylem differentiation frequency in a vascular induction system Vascular cell Induction culture System Using Arabidopsis Leaves (VISUAL) by utilizing a xylem-specific luciferase reporter line. In this quantitative system, TDIF suppressed and BR promoted xylem differentiation in a dose-dependent manner, respectively. T-DM1 cost Moreover, simultaneous treatment of TDIF and BR with (pro)cambial cells revealed that they can cancel their each other's effect on xylem differentiation, suggesting a competitive relationship between TDIF and BR. Thus, mutual inhibition of "ON" and "OFF" signal enables the fine-tuned regulation of xylem differentiation in the vascular meristem.Pericycle cells possess proliferative activity long after leaving the root apical meristem. Depending on the developmental stage and external stimuli, pericycle cell division leads to the production of lateral roots, vascular cambium and periderm, and callus. Therefore, pericycle cell division competence underlies root branching and secondary growth, as well as plant regeneration capacity. In this review, we first briefly present an overview of the molecular pathways of the four developmental programs originated, exclusively or partly, from pericycle cells. Then, we provide a review of up-to-date knowledge in the mechanisms determining pericycle cells' competence to undergo cell division. Furthermore, we discuss directions of future research to further our understanding of the pericycle's characteristics and functions.Since molecular phylogenetics recognized root nodule symbiosis (RNS) of all lineages as potentially homologous, scientists have tried to understand the "when" and the "how" of RNS evolution. Initial progress was made on understanding the timing of RNS evolution, facilitating our progress on understanding the underlying genomic changes leading to RNS. Here, we will first cover the different hypotheses on the timings of gains/losses of RNS and show how this has helped us understand how RNS has evolved. Finally, we will discuss how our improved understanding of the genetic changes that led to RNS is now helping us refine our understanding on when RNS has evolved.Compared with other organisms, plants have an extraordinary capacity for self-repair. Even if the entire tissues, including the stem cells, are resected, most plant species are able to completely regenerate whole tissues. However, the mechanism by which plants efficiently regenerate the stem cell niche during tissue reorganization is still largely unknown. Here, we found that the signaling mediated by plant steroid hormones brassinosteroids is activated during stem cell formation after root tip excision in Arabidopsis. Treatment with brassinazole, an inhibitor of brassinosteroid biosynthesis, delayed the recovery of stem cell niche after root tip excision. Regeneration of root tip after resection was also delayed in a brassinosteroid receptor mutant. Therefore, we propose that brassinosteroids participate in efficient root tip regeneration, thereby enabling efficient tissue regeneration to ensure continuous root growth after resection.Chengguan, the Urban Administrative Law Enforcement Bureau, has been criticized for its dismal public image and poor job performance. Based on an ethnographic case study in Z City, we analyzed the type of leadership that results in passive work performance in Chengguan, and we examined whether any leadership style can be used to improve Chengguan's image and performance. We developed a new leadership ontology of CNP (Cognition-Normalization-Performance) on this foundation, and ethnographic research was conducted in three phases leader's cognition, followers' normalization, and organization performance. Several implications were drawn. Leader selection should be cautious and can be improved by studying the leader's traits and behavior. This is done by investigating candidates' leadership career paths, trait characteristics, motive profiles, and other qualities. It is useful to change leaders by strengthening followers' unity and cohesion by setting up a labor union, youth federation, women's federation, and other groups. A leader should be selected among individuals who have completed leadership training as opposed to appointing one from outside the organization. On the one hand, the superior should help to improve the leadership environment (context), supervise problems in the organization's operation and performance, and track changes over time. On the other hand, the leader can also provide the followers with a flexible and adaptive place of work.With the COVID-19 pandemic, life satisfaction among college students has become a key issue at universities and in society. The current study explores the effects of belief in a just world and resilience on the relationship between relative deprivation and life satisfaction. A total of 787 college students from universities in China completed online questionnaires. Results showed that relative deprivation was negatively correlated with life satisfaction. Belief in a just world and resilience separately mediated the relationship between relative deprivation and life satisfaction. Moreover, a serial mediating effect of belief in a just world and resilience was observed between relative deprivation and life satisfaction. These findings suggest that relative deprivation may impair individuals' beliefs in a just world. Moreover, less belief in a just world may lower resilience and consequently decrease life satisfaction. This study enriches the research field of relative deprivation theory in the context of the COVID-19 pandemic, and provides a new interpretation and intervention perspective for improving college students' life satisfaction.