Differential Effects of Transgenerational Plasticity on Morphological and Photosynthetic Properties Between an Invasive Plant and Its Congeneric Native One

Transgenerational plasticity allows offsprings to be more adaptive in the environmental conditions experienced by their parents. It is suggested that differential effects of transgenerational plasticity on growth performance of offspring ramets may help to understand successful invasion of invasive plant with clonal growth comparing with its congeneric native one. A pot experiment using invasive herb Wedelia trilobata and its congeneric native species Wedelia chinensis was conducted to investigate differential effects of high/low light treatment experienced by mother ramets on morphological and photosynthetic properties of offspring ramets subjected to stressful low light treatment. For W. chinensis, stolon length and maximum carboxylation rate (Vmax) in offspring ramets from mother ramets subjected to low light treatment were significantly greater than those in offspring ramets from mother ramets subjected to high light treatment. For W. trilobata, leaf area and potential maximum net photosynthetic rate (Pmax) in offspring ramets from mother ramets subjected to low light treatment were significantly greater than those in offspring ramets from mother ramets subjected to high light treatment. We tentatively concluded that effects of transgenerational plasticity on morphological and photosynthetic properties among clonal plants could be species-specific. In addition, more favorable effect of transgenerational plasticity on growth performance was observed in the invasive plant than in its congeneric native species. It is suggested that transgenerational plasticity may be very important for successful invasion of invasive plant with clonal growth, especially in maternal environmental conditions. So, our experiment provides new insight into invasive mechanism of invasive plants.

BIOLOGIA REPRODUTIVA DE Neomarica northiana (SCHNEEV) SPRAGUE (IRIDACEAE): “MERANTHIA” - UM CASO ESPECIAL DE POLINIZAÇÃO = REPRODUCTIVE BIOLOGY OF Neomarica northiana (SCHNEEV) SPRAGUE (IRIDACEAE)

Este trabalho teve como objetivo estudar a biologia reprodutiva de Neomarica northiana (Schneev) Sprague (Iridaceae), erva perene que ocorre nas restingas do estado do Rio de Janeiro. A flor desta espécie apresenta três unidades funcionais de polinização denominada “meranthia”. O recurso floral oferecido aos polinizadores é a substância lipídica exsudada na base das tépalas. Análise de cromotografia gasosa das tépalas indicou a presença de limoneno. As flores de N. northiana são polinizadas exclusivamente por abelhas poliléticas de grande porte, Xylocopa sp.. Neomarica northiana é autocompatível. A produção de frutos por polinização natural foi maior do que a produção por polinização manual cruzada. A taxa de fecundidade é de 0,47. Neomarica northiana apresenta crescimento clonal que pode ocorrer de duas formas distintas, por meio do caule rizomatoso e por meio de bulbilhos formados na axila das brácteas.AbstractThe objective of this research was to evaluate the reproductive biology of Neomarica northiana (Iridaceae), a perennial herb that occurs in the Atlantic Coast restingas (humid subtropical broadleaf forest) of the state of Rio de Janeiro. Each flower of this species has three functional pollinating units called “meranthia”. The main floral resource provided to bees by Neomarica northiana is a lipid substance exuded at the base of the tepals. Gas-chromatographic analysis of tepal samples revealed the presence of limonene. Flowers of N. northiana are pollinated exclusively by large bodied species of bees (Xylocopa sp.). Fruit production from natural pollination is higher than from manual pollination. The fecundity rate is 0.47. Neomarica northiana has clonal growth, which may occur by means of the rhizomatous stem, which produces offshoots close to one another; or by means of axillary bulbils.

Deforestation is the turning point for the spreading of a weedy epiphyte: an IBM approach

The rapid spread of many weeds into intensely disturbed landscapes is boosted by clonal growth and self-fertilization strategies, which conversely increases the genetic structure of populations. Here, we use empirical and modeling approaches to evaluate the spreading dynamics of Tillandsia recurvata (L.) L. populations, a common epiphytic weed with self-reproduction and clonal growth widespread in dry forests and deforested landscapes in the American continent. We introduce the TRec model, an individual-based approach to simulate the spreading of T. recurvata over time and across landscapes subjected to abrupt changes in tree density with the parameters adjusted according to the empirical genetic data based on microsatellites genotypes. Simulations with this model showed that the strong spatial genetic structure observed from empirical data in T. recurvata can be explained by a rapid increase in abundance and gene flow followed by stabilization after ca. 25 years. TRec model’s results also indicate that deforestation is a turning point for the rapid increase in both individual abundance and gene flow among T. recurvata subpopulations occurring in formerly dense forests. Active reforestation can, in turn, reverse such a scenario, although with a milder intensity. The genetic-based study suggests that anthropogenic changes in landscapes may strongly affect the population dynamics of species with ‘weedy’ traits.

The Genetic and Environmental Adaptation of the Associated Liana Species Derris trifoliata Lour. (Leguminosae) in Mangroves

Derris trifoliata Lour. is an indigenous and associated liana species of mangroves in China; however, its rapid dispersal is threatening mangrove survival. To explore and evaluate their persistence in past disturbances and their potential resistance to future climate and environmental changes, 120 D. trifoliata samples were collected from three sites in Guangdong Province, China, and they were used to develop single nucleotide polymorphic markers using specific-locus amplified fragment sequencing technology. A total of 351.59 Mb reads and 97,998 polymorphic specific-locus amplified fragment sequencing tags were identified, including 360,672 single nucleotide polymorphisms. The principal component analysis, phylogenetic tree, and genetic structure all clustered the samples according to their geographic positions. The three populations showed medium genetic diversity levels and high clonal diversity, indicating that sexual propagation played vital roles in the populations’ succession, although clonal growth was intense within the populations. An association analysis revealed that 9 out of 16 markers were correlated with nitrogen, which indicated the positive roles of nitrogen in population formation and maintenance. This study provides an ecological and molecular basis for understanding the outbreaks of D. trifoliata in mangroves. To control the further expansion of D. trifoliata in mangroves, preventive and control measures should be taken against clonal growth and sexual propagation, respectively; obstructing the clonal growth, especially that of the stolon, should be mainly considered at the junctions of D. trifoliata and mangroves.

Whole-body clonal mapping identifies giant dominant clones in zebrafish skin epidermis

Skin expansion during development is predominantly driven by growth of basal epithelial cell (BEC)-derived clonal populations, which often display varied sizes and shapes. However, little is known about the causes of clonal heterogeneity and the maximum size to which a single clone can grow. Here, we created a zebrafish model, basebow, for capturing clonal growth behavior in the BEC population on a whole-body, centimeter scale. By tracking 222 BECs over the course of a 28-fold expansion of body surface area, we determined that most BECs survive and grow clonal populations with an average size of 0.013 mm2. An extensive survey of 742 sparsely labeled BECs further revealed that giant dominant clones occasionally arise on specific body regions, covering up to 0.6% of the surface area. Additionally, a growth-induced extracellular matrix component, Lamb1a, mediates clonal growth in a cell-autonomous manner. Altogether, our findings demonstrate how clonal heterogeneity and clonal dominance may emerge to enable post-embryonic growth of a vertebrate organ, highlighting key cellular mechanisms that may only become evident when visualizing single cell behavior at the whole animal level.

Adventitious rooting in response to long-term cold: a possible mechanism of clonal growth in alpine perennials

Arctic alpine species experience extended periods of cold and unpredictable conditions during flowering. Thus, often, alpine plants use both sexual and asexual means of reproduction to maximise fitness and ensure reproductive success. We used the arctic alpine perennial Arabis alpina to explore the role of prolonged cold exposure on adventitious rooting. We exposed plants to 4°C for different durations and scored the presence of adventitious roots on the main stem and axillary branches. Our physiological studies demonstrated that the presence of adventitious roots positively correlates with increased duration of exposure to cold treatment, with 21 weeks at 4 °C saturating the effect of cold on adventitious rooting. On the main stem adventitious roots developed in specific internodes. Transcriptomic and histological studies indicated that adventitious roots in A. alpina stems are initiated during cold exposure and emerge after plants experience growth promoting conditions. The emergence of the adventitious root primordia correlates with an increase in auxin response and free endogenous auxin in the stems. Our results highlight the role of low temperature during clonal growth in alpine plants and provide insights on the molecular mechanisms involved at different stages of adventitious rooting.

Basal cells in the epidermis and epidermal differentiation

A definite identification of epidermal stem cells is not known and the mechanism of epidermal differentiation is not fully understood. Toward both of these quests, considerable information is available from the research on lineage tracing and clonal growth analysis in the basal layer of the epidermis, on the hair follicle and interfollicular epidermal stem cells, and on Wnt signaling along with its role in developmental patterning and cell differentiation. In this paper, literature on the aforementioned research has been collated and analyzed. In addition, models of basal layer cellular composition and epidermal differentiation have been presented.

Re-evaluation of the Amazonian Hylaeaicum (Bromeliaceae: Bromelioideae) based on neglected morphological traits and molecular evidence

Generic status for the Amazonian Hylaeaicum is proposed within the Aechmea alliance, excluding it from the “Nidularioid complex” in general and from Neoregelia in particular. The monophyly of this new genus is supported by molecular phylogenetic analyses. The taxonomic circumscription of Hylaeaicum is based on the combination of geographical range and morphological characters, such as clonal growth, inflorescence structure, petal and corolla conformation, petal appendages, ovary, ovule, stigma, pollen, fruit, and seed, as well as seed anatomy, thoroughly documented and illustrated from field-collected specimens that flowered in cultivation in the Rio de Janeiro Botanical Garden, the Marie Selby Botanical Gardens, and in Refúgio dos Gravatás. The presence of seeds with long bicaudate appendages on both chalazal and micropylar ends is reported for the first time in Bromelioideae and considered an important character to distinguish Hylaeaicum from the related genera in the Aechmea alliance. In order to support the morphological distinctness of Hylaeaicum, the most varied and complete documentation of stigmata, fruits, and seeds of Bromelioideae is also presented for the first time, covering 24 genera and 17 subgenera. Fourteen new combinations, including 12 species and two varieties, are proposed.