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Flowers and fruits of Helleborus viridis subsp. occidentalis and its congener H. foetidus (note the different position of the sepals of the flower stage). Top left: flower of H. foetidus. Top right: flower of H. viridis subsp. occidentalis. Lower left: fruit of H. foetidus. Lower right: fruit of H viridis subsp. occidentalis.
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Species within the genus Helleborus differ in the relative location of their sepals. Previous studies have proved the existence of post-floral functionality of sepals in H. foetidus, which leads us to consider the possibility of differences in the functionality of the sepals in H. viridis subsp. occidentalis. In this study, we analyzed their influe...
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... in seed weight of Helleborus foetidus in response to a perianth reduction. In this species the persistent sepals remain erect in a closed tube-like position protecting the reproductive organs, and open to a transversal position at fruiting time. In contrast, H. viridis subsp. occidentalis presents open sepals since the opening of the buds (Fig. 1). We hypothesize that these two species may diff er in perianth functionality, due to their diff erential sepal display. To test this, we conducted an experiment to explore perianth contribution to female reproductive success in H. viridis subsp. occidentalis , measured as number and weight of seeds. Specifi cally, we 1) analyzed sepal ...
Citations
... Flowers of the Helleborus species do not consist of petals, but of sepals, while petals are transformed into nectaries. They may substitute the multiple roles of petals, as they attract pollinators, protect flowers, and regulate flower temperature [16]. Helleborus flowers are epiphyllous, non-specialised, and thus, are pollinated by a variety of insects, such as honeybees, bumblebees, different flies, and even wasps, ants, beetles, representatives of the genus Thysanoptera, and possibly wind, as in the case of H. niger [17]. ...
... This was also shown for H. niger [30] and H. foetidus [35]. During flower anthesis, the perianth of H. foetidus is tube-like, and it opens after pollination [16]. For H. viridis, contrasting results were obtained. ...
... Aschan et al. [33] showed that ripening fruits use respiratory carbon dioxide for photosynthesis and, thus, benefit in terms of the carbon budget. However, this was not the case in the study of Guitián and Larrinaga [16], who revealed that sepals persisting after flowering do not contribute to the development of seeds. High photosynthetic capacity of sepals in early phases, which we measured in H. odorus, is especially important, because this is an herbaceous species that has to use the advantage of favourable light conditions before the tree canopy closes [1]. ...
Helleborus niger is an evergreen species, while H. odorus is an herbaceous understorey species. They both develop flowers before the forest canopy layer closes. Their sepals remain after flowering and have multiple biological functions. To further elucidate the functions of sepals during flower development, we examined their optical and chemical properties, and the photochemical efficiency of photosystem II in the developing, flowering, and fruiting flowers. Sepals of the two species differed significantly in the contents of photosynthetic pigments and anthocyanins, but less in the UV-absorbing substances’ contents. Significant differences in photosynthetic pigment contents were also revealed within different developmental phases. The sepal potential photochemical efficiency of photosystem II was high in all developmental phases in H. odorus, whereas in H. niger, it was initially low and later increased. In the green H. odorus sepals, we obtained typical green leaf spectra with peaks in the green and NIR regions, and a low reflectance and transmittance in the UV region. On the other hand, in the white H. niger sepals in the developing and flowering phases, the response was relatively constant along the visible and NIR regions. Pigment profiles, especially chlorophylls, were shown to be important in shaping sepal optical properties, which confirms their role in light harvesting. All significant parameters together accounted for 44% and 34% of the reflectance and transmittance spectra variability, respectively. These results may contribute to the selection of Helleborus species and to a greater understanding of the ecological diversity of understorey plants in the forests.
... occidentalis. Authors suggested that differences in the timing of leaf development and changes in the position of floral organs among the different Helleborus species underlie a distinctive response to the ever-changing weather conditions (Guitián and Larrinaga, 2014). ...
Peace lily (Spathiphyllum wallisii Regel) is a herbaceous, commercially important ornamental plant characterized by greening of its originally white spathe during a post-anthesis period and fruit development. It is a useful model plant for gaining insight into source–sink relationship. To clarify what is the triggering signal for spathe greening and its potential physiological role, the greening process has been examined in fertilized vs unfertilized and decapitated (with spadix removed) plants. Results showed that spathe of fertilized plants is viable for a longer period of time and greening process is more intensive in comparison with decapitated or unfertilized plants. Greening process comprised chloroplast differentiation as well as chlorophyll accumulation, and resulted in the photosynthetically active organs. Photosynthesis performance index (PIABS) of spathe in fertilized flowers was significantly higher than that in unfertilized and decapitated plants, indicating its better overall photosynthetic performance. Spathe removal during fruit development revealed approximately 30% smaller fruits in comparison with intact ones, implicating that green spathe contribute significantly as assimilate source for developing fruits. Cytokinin analysis showed that t-Z-type cytokinins were the most abundant in the spadix (t-Z and t-ZR) and the greening spathe (t-ZR), while overall cytokinin pool was significantly lower in the spathe of the decapitated plants. Exogenous treatment of spathe in decapitated plants with t-Z enhanced the intensity of greening. We may conclude that spathe greening in peace lily is genetically programmed process that may be mediated by fructification and, in part, by cytokinins originated in the developing fruit which was confirmed herein for the first time.
... Green hellebore sepals have been estimated to contribute >60% to the whole-plant carbon gain (Aschan et al., 2005). The direct contribution of sepals to seed growth was studied in a number of different sepal removal experiments on hellebore species (Salopek-Sondi et al., 2000;Herrera, 2005;Salopek-Sondi and Magnus, 2007;Guitián and Larrinaga, 2014). Two of these studies showed that removal of all sepals directly after flowering is sufficient to cause a mild to severe reduction in seed growth (Salopek-Sondi et al., 2000;Herrera, 2005). ...
... Two of these studies showed that removal of all sepals directly after flowering is sufficient to cause a mild to severe reduction in seed growth (Salopek-Sondi et al., 2000;Herrera, 2005). However, later studies reported no difference in seed set or seed mass compared with controls (Salopek-Sondi and Magnus, 2007; Guitián and Larrinaga, 2014). It has been suggested that these differing results may be as a result of the presence or absence of leaves at the time of sepal removal. ...
... It has been suggested that these differing results may be as a result of the presence or absence of leaves at the time of sepal removal. The significance of sepal contribution to seed filling may further depend on environmental factors (Salopek-Sondi and Magnus, 2007;Guitián and Larrinaga, 2014). ...
During seed development, carbon is reallocated from maternal tissues to support germination and subsequent growth. As this pool of resources is depleted post-germination, the plant begins autotrophic growth through leaf photosynthesis. Photoassimilates derived from the leaf are used to sustain the plant and form new organs, including other vegetative leaves, stems, bracts, flowers, fruits, and seeds. In contrast to the view that reproductive tissues act only as resource sinks, many studies demonstrate that flowers, fruits, and seeds are photosynthetically active. The photosynthetic contribution to development is variable between these reproductive organs and between species. In addition, our understanding of the developmental control of photosynthetic activity in reproductive organs is vastly incomplete. A further complication is that reproductive organ photosynthesis (ROP) appears to be particularly important under suboptimal growth conditions. Therefore, the topic of ROP presents the community with a challenge to integrate the fields of photosynthesis, development, and stress responses. Here, we attempt to summarize our understanding of the contribution of ROP to development and the molecular mechanisms underlying its control.
... In some cases, perianth persistence has been found to Scientific REPORtS | (2019) 9:729 | DOI: 10.1038/s41598-018-37358-0 have beneficial effects on plant fitness by contributing photosynthates to developing fruits and seeds, heating the developing fruits, or protecting seeds from seed predation 2,14,16 . However, some studies report that the persistent calyx has no effect on the development of fruits 17,18 , or even decreases plant fitness because it provides larvae of frugivores with a refuge from parasitism, resulting in a higher percentage of fruits being eaten by larvae 19 . In addition, corolla retention often incurs physiological costs, such as investment in biomass, respiration and water loss by evaporation, which may negatively affect fruit and seed production [20][21][22] . ...
Corollas (or perianths), considered to contribute to pollinator attraction during anthesis, persist after anthesis in many plants. However, their post-floral function has been little investigated within a cost-benefit framework. We explored the adaptive significance of corolla retention after anthesis for reproduction in Fritillaria delavayi, a perennial herb endemic to the alpine areas of the Hengduan Mountains, southwestern China. We examined whether the persistent corollas enhance reproductive success during seed development. Persistent corollas increased fruit temperature on sunny days, and greatly decreased the intensity of ultraviolet-B/C (UV-B/C) radiation reaching fruits. When corollas were removed immediately after pollination, fecundity and progeny quality were adversely affected. Measurements of flower mass and size showed no further corolla growth during fruiting, and respiration and transpiration tests demonstrated that both respiration rate and transpiration rate of corollas were much lower during fruiting than during flowering, indicating a slight additional resource investment in corolla retention after anthesis. Thus, seed production by F. delavayi may be facilitated by corolla retention during seed development at only a small physiological cost. We conclude that corolla retention may be an adaptive strategy that enhances female reproductive success by having a protective role for ripening seeds in the harsh conditions at high elevation.
... Interestingly, all the organs produced by the flower whorls are active in photosynthesis and can provide a significant part of the carbon needed for reproduction (Aschan et al. 2005). Especially the green showy elements of the perianth, commonly classified as sepals and persisting beyond floral senescence and seed dispersion, are thought to play a substantial role in the production of photoassimilates (Guitián and Larrinaga 2014). The nectaries are derived from modified petals and secrete nectar continuously for about 20 days after flower anthesis (Vesprini et al. 1999;Guitián and Larrinaga 2014). ...
... Especially the green showy elements of the perianth, commonly classified as sepals and persisting beyond floral senescence and seed dispersion, are thought to play a substantial role in the production of photoassimilates (Guitián and Larrinaga 2014). The nectaries are derived from modified petals and secrete nectar continuously for about 20 days after flower anthesis (Vesprini et al. 1999;Guitián and Larrinaga 2014). Since ancient times, Helleborus bocconei Ten. is employed in traditional medicine with different therapeutic uses for humans and animals (Puglisi et al. 2009;Maior and Dobrotă 2013), and nowadays, it shows potential economic perspectives in terms of ornamental uses (Fascetti et al. 2014). ...
In this study, we investigated cytohistochemistry, cycle progression, and relative DNA content of the female gametophyte cells of Helleborus bocconei Ten. before and after fertilization process. The early stages of embryo development were also investigated. H. bocconei possesses a monosporic seven-celled/eight-nucleate Polygonum type female gametophyte, characterized by a morpho-functional polarity. The cells of the embryo sac showed abundant reserves of polysaccharides, strongly increasing in the egg cell just before fertilization. With different timing in DNA replication during cell cycle progression, synergids, egg cells, and polar nuclei showed a haploid DNA content at the end of their differentiation, while antipodes underwent three DNA endoreduplication cycles. Programmed cell death symptoms were detectable in synergid and antipodal cells. After double fertilization, the central cell quickly underwent many mitotic cycles forming the endosperm, which exhibited a progressive increase in protein bodies and starch grains. Close to the developing embryo, the endosperm differentiated a well-defined region rich in a fibrillar carbohydrate matrix. The zygote, that does not start immediately to divide after double fertilization, developed in to an embryo that reached the heart stage at fruit maturation time. A weakly differentiated embryo at this time indicates a morpho-physiological dormancy of seeds, as a survival strategy imposed by the life cycle of this plant with seed dispersal in spring and their germination in the following winter.
Abstract: The present study aims to review the presence of winged accrescent sepals in various plant families with emphasis to the Subfamilies, Tribes and genera of the Chenopodiaceae and their significance in classification. Winged accrescent sepals were found to be sporadically scattered in 24 dicotyledonous and two monocotyledonous, one Gymnosperm and one Bryophyte families. In the Chenopodiaceae, winged accrescent sepals are present in three Subfamilies, five Tribes and 26 genera. The present review showed that these modified sepals although are unique morphological features in certain genera, Tribes and Subfamilies in the family Chenopodiaceae, they are also encountered in unrelated families and are not supported by molecular characteristics. Within the Chenopodiaceae, both the genera Sarcobatus and Dysphania, possess winged accrescent sepals, but molecular characteristics support the transfer of the genus Sarcobatus to a separate family, and confirmed the position of Dysphania within the family Chenopodiaceae. In addition, based on molecular characteristics, Subfamily Polycnemoideae which doesn't possess winged accrescent sepals, shared similarity with the Chenopodiaceae
