Evolution of plant reproduction: from fusion and dispersal to interaction and communication

Based on the existing data concerning the evolution of the sexual reproduction, it is argued that the processes of sex differentiation and interactions play a key role in evolution. From the beginning environment and organism are unified. In a changing dynamic environment life originates and the interaction between life and environment develops from simple to more complex organisms. Sexual reproduction is introduced after the origin of meiosis and is a key process in evolution. The asexual reproduction process prepares to dispersal. Sexual reproduction process adds the genome renewal and the gamete-gamete interaction. Reproduction and dispersal are connected and the process of reproduction has similarities between asexual and sexual reproduction. Unicellular algae develop the physiological and morphological sex differentiation. Sex differentiation is connected with the way of dispersal. The step to multicellular plants introduces cell isolation after meiosis and by the stay on the mother plant within a cell or organ, plant-cell apoplastic interaction originates and by prolonged stay the plant-plant interaction. This stay influences the type of dispersal. A life cycle with alternation of generations and two moments of dispersal permits plants to go on land. In ferns a shift in the moment of sex differentiation to meiospore happens and the stay of the macrospore leads to the seed plants. In water all types of sexual reproduction, interactions and the alternation of generations are prepared and these are used to conquest land. On land the biotic dispersal is realized. The phylogeny of sexual reproduction reveals that the sex differentiation and interaction are the main causes in the evolution of sexual reproduction. Sexual reproduction shows interactions during gamete fusion, between organism and environment and in multicellular plants between organisms. With respect to other types of interaction as in symbiosis or the nutrient chain, interaction is considered as an important action which is based on a persisting cooperation and points to a push during evolution. The push is expressed as communication: the driving force in the evolution. Based on the interactions between organisms and interactions between organisms and the dynamic environment, communication is considered as a driving force leading to the evolution as explained in the development of plant reproduction. Consequences for reproduction, its regulation and the process of evolution are discusse

Editorial: Molecular mechanisms of flowering plant reproduction

Plant reproduction is an intricate process important for the survival of all dominant autotrophs and critical in agriculture and stable food production as the basis of our diet. Angiosperms undergo extreme transformations during their ontogeny, leading to the reproductive transition. During this process, several steps are needed, including transforming a shoot apical or a lateral vegetative meristem into an inflorescence meristem with flowering competence. Floral meristems are formed from the latter accompanied by cell differentiation leading to gamete formation in specialized reproductive floral organs. Gamete interaction relies on successful pollination, whether that occurs via biotic or abiotic vectors. In addition, fertilization requires numerous molecular and hormonal signals in place and results in proper pollen tube growth, zygote viability, and seed formation. This Research Topic addresses some of the most outstanding discoveries on angiosperm reproduction in model species like Arabidopsis thaliana and Oryza sativa and crops like cauliflower, cassava, citrus, and sugarcane, among others. In the papers on the topic, the reader will discover highlights on extremely diverse floral promotion pathways, mechanisms of floral organ identity and morphogenesis, sporogenesis and gametogenesis, pollen presentation, pollination, and fertilization strategies.Fil: Pabón Mora, Natalia. Universidad de Antioquia; ColombiaFil: Goldman, Maria Helena S.. Universidade de Sao Paulo; BrasilFil: Smyth, David R.. Monash University; AustraliaFil: Muschietti, Jorge Prometeo. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; ArgentinaFil: Costa, Maria Manuela R.. Universidade do Minho; Portuga

The Cenomanian/Turonian boundary in light of new developments in terrestrial palynology

The Cenomanian/Turonian boundary interval is associated with an oceanic anoxic event (OAE 2,  94.0 Ma) during one of the warmest episodes in the Mesozoic. To date, plant responses to these climatic conditions are known only from the northern mid-latitudinal succession in Cassis, France. There, conifer-dominated and angiosperm-dominated vegetation types alternate. However, whether the exceptional environmental conditions had an impact on plant reproduction is unknown to date. We applied a new environmental proxy based on spore and pollen teratology on palynological samples from the Cassis succession, to explore if this phenomenon also occurs across the OAE 2. The observed frequencies of<1% malformed spores and pollen grains suggest that plant reproduction was not affected during the Cenomanian/Turonian boundary interval. While the effects of continental Large Igneous Province(s) on plant reproduction have shown to produce abnormal spore or pollen morphologies as evidence for severe environmental pollution, by contrast the effects of oceanic LIP(s) seems to be inconsequential

The Cenomanian/Turonian boundary in light of new developments in terrestrial palynology

The Cenomanian/Turonian boundary interval is associated with an oceanic anoxic event (OAE 2, 94.0 Ma) during one of the warmest episodes in the Mesozoic. To date, plant responses to these climatic conditions are known only from the northern mid-latitudinal succession in Cassis, France. There, conifer-dominated and angiosperm-dominated vegetation types alternate. However, whether the exceptional environmental conditions had an impact on plant reproduction is unknown to date. We applied a new environmental proxy based on spore and pollen teratology on palynological samples from the Cassis succession, to explore if this phenomenon also occurs across the OAE 2. The observed frequencies of<1% malformed spores and pollen grains suggest that plant reproduction was not affected during the Cenomanian/Turonian boundary interval. While the effects of continental Large Igneous Province(s) on plant reproduction have shown to produce abnormal spore or pollen morphologies as evidence for severe environmental pollution, by contrast the effects of oceanic LIP(s) seems to be inconsequential

De novo sequencing of the Hypericum perforatum L. flower transcriptome to identify potential genes that are related to plant reproduction sensu lato

Background: St. John's wort (Hypericum perforatum L.) is a medicinal plant that produces important metabolites with antidepressant and anticancer activities. Recently gained biological information has shown that this species is also an attractive model system for the study of a naturally occurring form of asexual reproduction called apomixis, which allows cloning plants through seeds. In aposporic gametogenesis, one or multiple somatic cells belonging to the ovule nucellus change their fate by dividing mitotically and developing functionally unreduced embryo sacs by mimicking sexual gametogenesis. Although the introduction of apomixis into agronomically important crops could have revolutionary implications for plant breeding, the genetic control of this mechanism of seed formation is still not well understood for most of the model species investigated so far. We used Roche 454 technology to sequence the entire H. perforatum flower transcriptome of whole flower buds and single flower verticils collected from obligately sexual and unrelated highly or facultatively apomictic genotypes, which enabled us to identify RNAs that are likely exclusive to flower organs (i.e., sepals, petals, stamens and carpels) or reproductive strategies (i.e., sexual vs. apomictic). Results: Here we sequenced and annotated the flower transcriptome of H. perforatum with particular reference to reproductive organs and processes. In particular, in our study we characterized approximately 37,000 transcripts found expressed in male and/or female reproductive organs, including tissues or cells of sexual and apomictic flower buds. Ontological annotation was applied to identify major biological processes and molecular functions involved in flower development and plant reproduction. Starting from this dataset, we were able to recover and annotate a large number of transcripts related to meiosis, gametophyte/gamete formation, and embryogenesis, as well as genes that are exclusively or preferentially expressed in sexual or apomictic libraries. Real-Time RT-qPCR assays on pistils and anthers collected at different developmental stages from accessions showing alternative modes of reproduction were used to identify potential genes that are related to plant reproduction sensu lato in H. perforatum. Conclusions: Our approach of sequencing flowers from two fully obligate sexual genotypes and two unrelated highly apomictic genotypes, in addition to different flower parts dissected from a facultatively apomictic accession, enabled us to analyze the complexity of the flower transcriptome according to its main reproductive organs as well as for alternative reproductive behaviors. Both annotation and expression data provided original results supporting the hypothesis that apomixis in H. perforatum relies upon spatial or temporal mis-expression of genes acting during female sexual reproduction. The present analyses aim to pave the way toward a better understanding of the molecular basis of flower development and plant reproduction, by identifying genes or RNAs that may differentiate or regulate the sexual and apomictic reproductive pathways in H. perforatum

Advances in plant reproduction: from gametes to seeds

At a time of unprecedented human population growth, climate change, and losses in biodiversity, plant reproduction is a particularly strategic research topic. From the very moment that a sporophytic cell switches its developmental pathway to become the megasporocyte or microsporocyte until a seed is finally formed, an intricate network of tightly regulated signalling pathways is in action. In recent years our understanding of the plant reproductive system has evolved enormously, and at a great pace. This special issue includes a collection of reviews that present the current state of the art across several areas of research in plant reproduction

The Buds and the Bees: Inquiry into the Sexual Reproduction of Plants

Many students have few significant experiences investigating flower structure and function, yet are expected to understand sexual reproduction in angiosperms. We present here an inquiry-based hands-on activity where middle school students compare plant reproduction to more commonly understood animal reproduction. This provides a foundation to more deeply understand topics related to plant reproduction. This activity also provides many opportunities to explicitly address the nature of science and how science works. This article addresses National Science Education Content Standards A, C, and G, and Iowa Teaching Standards 1, 2, 3, 4, and 5

Impacts of anthropogenic change on plant reproduction and fitness

Humans are altering natural systems around the globe in myriad ways. For plant species, such anthropogenic changes have resulted in increasingly fragmented populations, desynchronized interactions with mutualists, and shifted geographic ranges, among other effects. However, despite numerous examples of human impacts on plant populations, the consequences of these changes on plant reproduction remain poorly understood. In my thesis, I investigate the impacts of two forms of anthropogenic change–habitat disturbance and climate warming–on plant reproduction and fitness. I take two distinct approaches to address questions posed at local and regional scales. In Chapter I, I ask how inbreeding depression varies across the life cycle of the critically imperiled California endemic species, Collinsia corymbosa (Plantaginaceae). I show that, consistent with other primarily outcrossing species, inbreeding depression in C. corymbosa is most pronounced late in life history, specifically during the female reproductive phase of the life cycle. Inbred plants demonstrated significantly lower rates of autonomous autogamy (δ [delta] = 0.448) and flower production (δ [delta] = 0.225), limiting the ability of this species to set seed in the absence of pollinators. In Chapter II, I ask whether flowering and fruiting dates have advanced for 14 spring-flowering plant species in the Blue Ridge and Ridge & Valley ecoregions of eastern Tennessee over the past century. Additionally, I investigate how phenological sensitivity to spring temperature varies between ecoregions. Utilizing phenological observations sourced from 1000+ digitized herbarium specimens, I show that the sensitivity of flowering phenology to spring temperature at the community level varies between the Ridge & Valley and Blue Ridge (2.7 and 1.3 days earlier per degree Celsius warming, respectively). Further, I show that, while the flowering phenology of the majority of species investigated is sensitive to spring temperature in both ecoregions, flowering and fruiting dates have not significantly advanced in recent decades. Overall, I found variation in plant reproductive responses to anthropogenic change at the maternal family, population, species, community, and regional levels. Together, my research demonstrates that assessing reproduction and fitness at these multiple scales provides nuanced insights into the adaptive capacity and ultimate persistence of species in the Anthropocene