Flower Development in the Solanaceae.

Flower development is the process leading from a reproductive meristem to a mature flower with fully developed floral organs. This multi-step process is complex and involves thousands of genes in intertwined regulatory pathways; navigating through the FLOR-ID website will give an impression of this complexity and of the astonishing amount of work that has been carried on the topic (Bouché et al., Nucleic Acids Res 44:D1167-D1171, 2016). Our understanding of flower development mostly comes from the model species Arabidopsis thaliana, but numerous other studies outside of Brassicaceae have helped apprehend the conservation of these mechanisms in a large evolutionary context (Moyroud and Glover, Curr Biol 27:R941-R951, 2017; Smyth, New Phytol 220:70-86, 2018; Soltis et al., Ann Bot 100:155-163, 2007). Integrating additional species and families to the research on this topic can only advance our understanding of flower development and its evolution.In this chapter, we review the contribution that the Solanaceae family has made to the comprehension of flower development. While many of the general features of flower development (i.e., the key molecular players involved in flower meristem identity, inflorescence architecture or floral organ development) are similar to Arabidopsis, our main objective in this chapter is to highlight the points of divergence and emphasize specificities of the Solanaceae. We will not discuss the large topics of flowering time regulation, inflorescence architecture and fruit development, and we will restrict ourselves to the mechanisms included in a time window after the floral transition and before the fertilization. Moreover, this review will not be exhaustive of the large amount of work carried on the topic, and the choices that we made to describe in large details some stories from the literature are based on the soundness of the functional work performed, and surely as well on our own preferences and expertise.First, we will give a brief overview of the Solanaceae family and some of its specificities. Then, our focus will be on the molecular mechanisms controlling floral organ identity, for which extended functional work in petunia led to substantial revisions to the famous ABC model. Finally, after reviewing some studies on floral organ initiation and growth, we will discuss floral organ maturation, using the examples of the inflated calyx of the Chinese lantern Physalis and petunia petal pigmentation.

The ABC of Flower Development in Monocots: The Model of Rice Spikelet.

The initial seminal studies of flower developmental genetics were made from observations in several eudicot model species, particularly Arabidopsis and Antirrhinum. However, an increasing amount of research in monocot model and crop species is finally giving the credit that monocots deserve for their position in the evolutionary history of Angiosperms, their astonishing diversification and adaptation, their diversified floral structures, their pivotal function in most ecosystems on Earth and, finally, their importance in agriculture and farming, economy, landscaping and feeding mankind. Rice is a staple crop and the major monocot model to study the reproductive phase and flower evolution. Inspired by this, this chapter reviews a story of highly conserved functions related to the ABC model of flower development. Nevertheless, this model is complicated in rice by cases of gene neofunctionalization, like the recruitment of MADS-box genes for the development of the unique organs known as lemma and palea, subfunctionalization, and rewiring of conserved molecular pathways.

Violence Toward and by Youth: Part I: Looking for the "Whys".

Violence is a public health crisis. It is especially concerning when it involves youth, whether they be victims, perpetrators, or observers. Part 1 of this two-part series categorizes the types of violence toward and by youth. There is a great deal of information on the prevalence of violence, mostly related to school shootings. However, the literature provides limited information on the antecedents of violent behaviors, and there is a dearth of information on "why" youth engage in violence. This is the unanswered question that drives Part 1 of this series. The beginning steps to understand "why" are viewed through the lens of a modified ABC Model (antecedent, behavior, consequence). Interventions for youth violence will be explored in Part 2.

How flower development genes were identified using forward genetic screens in Arabidopsis thaliana.

In the later part of the 1980s, the time was ripe for identifying genes controlling flower development. In that pregenomic era, the easiest way to do this was to induce random mutations in seeds by chemical mutagens (or irradiation) and to screen thousands of plants for those with phenotypes specifically defective in floral morphogenesis. Here, we discuss the results of premolecular screens for flower development mutants in Arabidopsis thaliana, carried out at Caltech and Monash University, emphasizing the usefulness of saturation mutagenesis, multiple alleles to identify full loss-of-function, conclusions based on multiple mutant analyses, and from screens for enhancer and suppressor modifiers of original mutant phenotypes. One outcome was a series of mutants that led to the ABC floral organ identity model (AP1, AP2, AP3, PI, and AG). In addition, genes controlling flower meristem identity (AP1, CAL, and LFY), floral meristem size (CLV1 and CLV3), development of individual floral organ types (CRC, SPT, and PTL), and inflorescence meristem properties (TFL1, PIN1, and PID) were defined. These occurrences formed targets for cloning that eventually helped lead to an understanding of transcriptional control of the identity of floral organs and flower meristems, signaling within meristems, and the role of auxin in initiating floral organogenesis. These findings in Arabidopsis are now being applied to investigate how orthologous and paralogous genes act in other flowering plants, allowing us to wander in the fertile fields of evo-devo.

Cloning and Expression Analysis of Onion (Allium cepa L.) MADS-Box Genes and Regulation Mechanism of Cytoplasmic Male Sterility.

Flower organ development is one of the most important processes in plant life. However, onion CMS (cytoplasmic male sterility) shows an abnormal development of floral organs. The regulation of MADS-box transcription factors is important for flower development. To further understand the role of MADS-box transcription factors in the regulation of cytoplasmic male sterility onions. We cloned the full-length cDNA of five MADS-box transcription factors from the flowers of onion using RACE (rapid amplification of cDNA ends) technology. We used bioinformatics methods for sequence analysis and phylogenetic analysis. Real-time quantitative PCR was used to detect the expression patterns of these genes in different onion organs. The relative expression levels of five flower development genes were compared in CMS onions and wild onions. The results showed that the full-length cDNA sequences of the cloned MADS-box genes AcFUL, AcDEF, AcPI, AcAG, and AcSEP3 belonged to A, B, C, and E MADS-box genes, respectively. A phylogenetic tree construction analysis was performed on its sequence. Analysis of MADS-box gene expression in wild onion and CMS onion showed that the formation of CMS onion was caused by down-regulation of AcDEF, AcPI, and AcAG gene expression, up-regulation of AcSEP3 gene expression, and no correlation with AcFUL gene expression. This work laid the foundation for further study of the molecular mechanism of onion flower development and the molecular mechanism of CMS onion male sterility.

Violence Toward and by Youth: Part II: Recommendations for Violence Interventions in the School Setting.

Violence toward and by youth is a public health crisis that can partially be addressed by the modified Antecedent, Behavior, Consequence (ABC) Model. Part I of this two-part series discussed the types of violence and the risk and protective factors that affect the prevalence of violence; it also addressed the emotions and thoughts that occur before the behaviors to help explain "why" youth engage in violence. Part II focuses on possible interventions by the school nurse and school staff. The modified ABC Model allows school nurses to focus on interventions that address the emotions and thoughts resulting from the antecedents as well as promote protective factors. Through their role in primary prevention, school nurses can also address risk factors for violence and participate in school and the wider community's efforts to mitigate violence.

Genome-Wide Analyses of MADS-Box Genes in Humulus lupulus L. Reveal Potential Participation in Plant Development, Floral Architecture, and Lupulin Gland Metabolism.

MADS-box transcription factors (TFs) are involved in multiple plant development processes and are most known during the reproductive transition and floral organ development. Very few genes have been characterized in the genome of Humulus lupulus L. (Cannabaceae), an important crop for the pharmaceutical and beverage industries. The MADS-box family has not been studied in this species yet. We identified 65 MADS-box genes in the hop genome, of which 29 encode type-II TFs (27 of subgroup MIKCC and 2 MIKC*) and 36 type-I proteins (26 α, 9 ß, and 1 γ). Type-II MADS-box genes evolved more complex architectures than type-I genes. Interestingly, we did not find FLOWERING LOCUS C (FLC) homologs, a transcription factor that acts as a floral repressor and is negatively regulated by cold. This result provides a molecular explanation for a previous work showing that vernalization is not a requirement for hop flowering, which has implications for its cultivation in the tropics. Analysis of gene ontology and expression profiling revealed genes potentially involved in the development of male and female floral structures based on the differential expression of ABC homeotic genes in each whorl of the flower. We identified a gene exclusively expressed in lupulin glands, suggesting a role in specialized metabolism in these structures. In toto, this work contributes to understanding the evolutionary history of MADS-box genes in hop, and provides perspectives on functional genetic studies, biotechnology, and crop breeding.

Rational Dictators in the Dictator Game Are Seen as Cold and Agentic but Not Intelligent.

In Dictator Games, dictators decide how much of a given endowment to send to receivers with no further interactions. We explored the social inferences people draw about dictators from the dictators' money amount sent and vice versa in 11 experiments (N = 1,425): Participants rated "unfair" dictators, who sent little or no money, as more agentic, but less communal than "fair" dictators, who sent half of the endowment. Conversely, participants expected more agentic and conservative but less communal dictators to send less money than less agentic, more liberal, or more communal dictators. Participants also rated unfair dictators as less intelligent but expected less intelligent dictators to send more money. When participants played the Dictator Game with real money, only self-reported communion predicted the money amount sent. Thus, participants' inferences might not reflect reality, but rational social actors should not only fear to appear unfair but also unintelligent.

Transcript Profiling of MIKCc MADS-Box Genes Reveals Conserved and Novel Roles in Barley Inflorescence Development.

MADS-box genes have a wide range of functions in plant reproductive development and grain production. The ABCDE model of floral organ development shows that MADS-box genes are central players in these events in dicotyledonous plants but the applicability of this model remains largely unknown in many grass crops. Here, we show that transcript analysis of all MIKCc MADS-box genes through barley (Hordeum vulgare L.) inflorescence development reveals co-expression groups that can be linked to developmental events. Thirty-four MIKCc MADS-box genes were identified in the barley genome and single-nucleotide polymorphism (SNP) scanning of 22,626 barley varieties revealed that the natural variation in the coding regions of these genes is low and the sequences have been extremely conserved during barley domestication. More detailed transcript analysis showed that MADS-box genes are generally expressed at key inflorescence developmental phases and across various floral organs in barley, as predicted by the ABCDE model. However, expression patterns of some MADS genes, for example HvMADS58 (AGAMOUS subfamily) and HvMADS34 (SEPALLATA subfamily), clearly deviate from predicted patterns. This places them outside the scope of the classical ABCDE model of floral development and demonstrates that the central tenet of antagonism between A- and C-class gene expression in the ABC model of other plants does not occur in barley. Co-expression across three correlation sets showed that specifically grouped members of the barley MIKCc MADS-box genes are likely to be involved in developmental events driving inflorescence meristem initiation, floral meristem identity and floral organ determination. Based on these observations, we propose a potential floral ABCDE working model in barley, where the classic model is generally upheld, but that also provides new insights into the role of MIKCc MADS-box genes in the developing barley inflorescence.

Spatio-Temporal Dynamics of the Patterning of Arabidopsis Flower Meristem.

The qualitative model presented in this work recovers the onset of the four fields that correspond to those of each floral organ whorl of Arabidopsis flower, suggesting a mechanism for the generation of the positional information required for the differential expression of the A, B, and C identity genes according to the ABC model for organ determination during early stages of flower development. Our model integrates a previous model for the emergence of WUS pattern in the floral meristem, and shows that this pre-pattern is a necessary but not sufficient condition for the posterior information of the four fields predicted by the ABC model. Furthermore, our model predicts that LFY diffusion along the L1 layer of cells is not a necessary condition for the patterning of the floral meristem.

The ABC of society: Perceived similarity in agency/socioeconomic success and conservative-progressive beliefs increases intergroup cooperation.

The dimensions that explain which societal groups cooperate more with which other groups remain unclear. We predicted that perceived similarity in agency/socioeconomic success and conservative-progressive beliefs increases cooperation across groups. Self-identified members (N = 583) of 30 society-representative U.S. groups (gays, Muslims, Blacks, upper class, women, Democrats, conservatives etc.) played an incentivized one-time continuous prisoner's dilemma game with one self-identified member of each of these groups. Players knew nothing of each other except one group membership. Consistent with the ABC (agency-beliefs-communion) model of spontaneous stereotypes, perceived self-group similarity in agency and beliefs independently increased expected and actual cooperation across groups, controlling for shared group membership. Similarity in conservative-progressive beliefs had a stronger effect on cooperation than similarity in agency, and this effect of similarity in beliefs was stronger for individuals with extreme (progressive or conservative) compared to moderate beliefs.

Dissection of the Arabidopsis HUA-PEP gene activity reveals that ovule fate specification requires restriction of the floral A-function.

Ovules are essential for sexual plant reproduction and seed formation, and are fundamental for agriculture. However, our understanding of the molecular mechanisms governing ovule development is far from complete. In Arabidopsis, ovule identity is determined by homeotic MADS-domain proteins that define the floral C- (AG) and D- (SHP1/SHP2, STK) functions. Pre-mRNA processing of these genes is critical and mediated by HUA-PEP activity, composed of genes encoding RNA-binding proteins. In strong hua-pep mutants, functional transcripts for C- and D-function genes are reduced, resulting in homeotic transformation of ovules. Thus, hua-pep mutants provide an unique sensitized background to study ovule morphogenesis when C- and D-functions are simultaneously compromised. We found that hua-pep ovules are morphologically sepaloid and show ectopic expression of the homeotic class-A gene AP1. Inactivation of AP1 or AP2 (A-function genes) in hua-pep mutants reduced homeotic conversions, rescuing ovule identity while promoting carpelloid traits in transformed ovules. Interestingly, increased AG dosage led to similar results. Our findings strongly suggest that HUA-PEP activity is required for correct C and D floral functions, which in turn prevents ectopic expression of class-A genes in ovules for their proper morphogenesis, evoking the classic A-C antagonism of the ABC model for floral organ development.

Adopting Text Mining on Rehabilitation Therapy Repositioning for Stroke.

Stroke is a common disabling disease that severely affects the daily life of patients. Accumulating evidence indicates that rehabilitation therapy can improve movement function. However, no clear guidelines have specific and effective rehabilitation therapy schemes, and the development of new rehabilitation techniques has been relatively slow. This study used a text mining approach, the ABC model, to identify an existing rehabilitation candidate therapy method that is most likely to be repositioned for stroke. In the model, we built the internal links of stroke (A), assessment scales (B), and rehabilitation therapies (C) in PubMed and the links were related to upper limb function measurements for patients with stroke. In the first step, using E-utility, we retrieved both stroke-related assessment scales and rehabilitation therapy records and then compiled two datasets, which were called Stroke_Scales and Stroke_Therapies, respectively. In the next step, we crawled all rehabilitation therapies co-occurring with the Stroke_Therapies and then named them as All_Therapies. Therapies that were already included in Stroke_Therapies were deleted from All_Therapies; therefore, the remaining therapies were the potential rehabilitation therapies, which could be repositioned for stroke after subsequent filtration by a manual check. We identified the top-ranked repositioning rehabilitation therapy and subsequently examined its clinical validation. Hand-arm bimanual intensive training (HABIT) was ranked the first in our repositioning rehabilitation therapies and had the most interaction links with Stroke_Scales. HABIT significantly improved clinical scores on assessment scales [Fugl-Meyer Assessment (FMA) and action research arm test (ARAT)] in the clinical validation study for acute stroke patients with upper limb dysfunction. Therefore, based on the ABC model and clinical validation, HABIT is a promising repositioned rehabilitation therapy for stroke, and the ABC model is an effective text mining approach for rehabilitation therapy repositioning. The findings in this study would be helpful in clinical knowledge discovery.

Reconstructing the ancestral flower of extant angiosperms: the 'war of the whorls' is heating up.

The origin of the angiosperm flower is a long-standing problem of botany and evolutionary biology. One widely accepted milestone towards solving it is the reconstruction of the ancestral flower of extant angiosperms, here termed 'AFEA'. A recent approach employing novel methods gave results that were not anticipated. Most notably the reconstructed phyllotaxis of AFEA soon was criticized and sparked a heated debate in the literature. To better explain, clarify, and perhaps cool the debate, we first summarize the results of previous attempts to reconstruct AFEA and contrast them with the more recent, controversial prediction of its structure. We then outline the major arguments made by contrasting parties in the recent debate. Finally, we discuss two key topics, the molecular mechanism of phyllotaxis and the role of gene regulatory networks during flower development and evolution, that may help to clarify the issue in the intermediate future.

AGLF provides C-function in floral organ identity through transcriptional regulation of AGAMOUS in Medicago truncatula.

Floral development is one of the model systems for investigating the mechanisms underlying organogenesis in plants. Floral organ identity is controlled by the well-known ABC model, which has been generalized to many flowering plants. Here, we report a previously uncharacterized MYB-like gene, AGAMOUS-LIKE FLOWER (AGLF), involved in flower development in the model legume Medicago truncatula Loss-of-function of AGLF results in flowers with stamens and carpel transformed into extra whorls of petals and sepals. Compared with the loss-of-function mutant of the class C gene AGAMOUS (MtAG) in M. truncatula, the defects in floral organ identity are similar between aglf and mtag, but the floral indeterminacy is enhanced in the aglf mutant. Knockout of AGLF in the mutants of the class A gene MtAP1 or the class B gene MtPI leads to an addition of a loss-of-C-function phenotype, reflecting a conventional relationship of AGLF with the canonical A and B genes. Furthermore, we demonstrate that AGLF activates MtAG in transcriptional levels in control of floral organ identity. These data shed light on the conserved and diverged molecular mechanisms that control flower development and morphology among plant species.

Molecular regulation of flower development.

Over the past three decades, several hundred genes with important regulatory functions during reproductive development in angiosperms have been identified. While we do not yet know, in most cases, how these genes and their products act, fundamental insights into the molecular mechanisms underlying the formation of flowers have been obtained in recent years. These advances were made possible to a large extent by studying the functions of master regulators of flower development through a multitude of experimental approaches, ranging from basic genetic analysis to genome-wide surveys. Based on the results of this work, several models for the molecular control of flower formation have been proposed, which have been tested and largely validated. These models have guided and informed research in the field, and facilitated recent efforts to delineate the composition and architecture of the gene regulatory networks underlying flower development. In this chapter, we aim to describe the current state of flowering research with a focus on recent progress in the field. We also discuss open questions that we believe need to be addressed in the future to further our understanding of the regulatory mechanisms that control floral morphogenesis and evolution.

Plus ça change, plus c'est la même chose: The developmental evolution of flowers.

The study of floral developmental evolution may be as old as the study of botany itself, but its history as a modern field largely dates to the characterization of the ABC model of floral organ identity. As we have come to understand more about the wide range of genetic programs that influence floral development, the potential for comparative studies has increased, leading to a steady expansion of research questions. This review attempts to take a broad view of these many questions, highlighting classic and recent findings that are shaping the way we think about floral evolution. Conservation of genetic pathways is a common theme, but there are often differences, whether due to drift or co-option, that have the potential to surprise. On the whole, the field of floral evo-devo is in transition, as we apply new approaches that allow us to move away from our reliance on candidate genes and, potentially, discover genuinely new developmental mechanisms.

Gene networks orchestrated by MeGI: a single-factor mechanism underlying sex determination in persimmon.

Separating male and female sex organs is one of the main strategies used to maintain genetic diversity within a species. However, the genetic determinants and their regulatory mechanisms have been identified in only a few species. In dioecious persimmons, the homeodomain transcription factor, MeGI, which is the target of a Y chromosome-encoded small-RNA, OGI, can determine floral sexuality. The basic features of this system are conserved in the monoecious hexaploid Oriental persimmon, in which an additional epigenetic regulation of MeGI determines floral sexuality. The downstream regulatory pathways of MeGI remain uncharacterized. In this study, we examined transcriptomic data for male and female flowers from monoecious persimmon cultivars to unveil the gene networks orchestrated by MeGI. A network visualization and cistrome assessment suggested that class-1 KNOTTED-like homeobox (KNOX)/ovate family protein (OFP)/growth regulating factors (GRFs) and short vegetative phase (SVP) genes mediate the differences in gynoecium and androecium development between male and female flowers, respectively. The expression of these genes is directly controlled by MeGI. The gene networks also suggested that some cytokinin, auxin, and gibberellin signaling genes function cooperatively in the KNOX/OFP/GRF pathway during gynoecium differentiation. Meanwhile, SVP may repress PI expression in developing androecia. Overall, our results suggest that MeGI evolved the ability to promote gynoecium development and suppress androecium development by regulating KNOX/OFP/GRF and SVP expression levels, respectively. These insights may help to clarify the molecular mechanism underlying the production of unisexual flowers, while also elucidating the physiological background enabling a single-factor system to establish dioecy in plants.