Reproductive biology of Pittosporum dasycaulon Miq., (Family Pittosporaceae) a rare medicinal tree endemic to Western Ghats

Reproductive Capacity and Scanning Electron Microscopy (SEM) Analyses of the Micromorphological Surfaces of Three Endemic Satureja Species from Bulgaria

Satureja pilosa Velen., S. coerulea Janka and S. kitaibelii Wierzb. ex Heuff. are Balkan endemic species, and they are distributed in restricted territories, primarily found in dry grasslands, rocky slopes, and stony habitats. This study presents the results of the first embryological and micromorphological analyses of three Satureja species (S. pilosa, S. kitaibelii, and S. coerulea) from the Bulgarian flora. The aim of this study was to establish the features of the male and female reproductive sphere, as well as surface characteristics of leaves, stem, and calyx in order to understand the mode of reproduction, character, size and state of species populations and delimitation. For the embryological study, flowers and flower buds in different developmental stages were collected from plants of natural populations and treated with the classic paraffin method. Reproductive capacity was assessed using the following approaches: (1) acetocarmine test for pollen viability, (2) tetrazolium test (TTZ) for seed viability, and (3) germination test. The surfaces characteristics of leaves, stem, and calyx were analyzed by scanning electron microscopy (SEM). As a result, the study revealed the structures of the male (M) and female (F) generative spheres as well as the processes of gamete development, pollination, and endosperm and embryo formation. It was found that the three Satureja species exhibited a high pollen viability but low seed viability and germination. The SEM analysis showed both common and distinct micromorphology features regarding epidermis, calyx and stem surfaces among the three Satureja species. Notably, the S. coerulea surfaces (leaves, calyx, stem) were clearly distinguishable from the other two Satureja species. Regarding the nutlet surfaces, it was observed that the exocarp surfaces of S. coerulea and S. kitaibelii have a reticulate convex type surface and comprise two types of cells: (1) highly bulging, bubble-like cells; and (2) flat cells with numerous striations. On the other hand, the exocarp of S. pilosa displayed rectangular or polygonal shapes without bubble-like cells, and it had a tabular to slightly convex type surface. Additionally, nutlets (seeds) of both S. coerulea and S. pilosa exhibited distinct papilla formations resembling non-glandular trichomes seen on the ends of the nutlets for S. coerulea and over the entire surface for S. pilosa. The characteristics of the embryological structures and processes, along with the absence of apomixis, characterized the three studied Satureja species as sexually reproducing. The established balanced processes and stable structures contribute to their high reproductive potential and population stability. However, these traits may also decrease their adaptability to environmental changes.

Reproductive Biology and Pollination Ecology of Fritillaria michailovskyi Fomin (Liliaceae), Endemic to East Anatolia (Turkey)

Fritillaria is highly endangered in their natural habitats, and these species are perennial bulbous plants with an important medicinal and ornamental value whose reproductive strategies and adaptive evolution mechanisms are still not fully clear. Therefore, the reproductive strategies of endemic species, like Fritillaria michailovskyi Fomin are important to detect the community structure and the diversity patterns of ornamental plants. The current paper on the reproductive strategy of F. michailovskyi, a rare endemic species, was carried out at the Erzincan Horticultural Research Institute, Turkey. Our results indicate that the flowering stages of F. michailovskyi may be divided into eight phases. According to pollination experiments and the pollen/ovule ratio, and the self-incompatibility index (SII) in an ex-situ population, F. michailovskyi indicated high levels of xenogamy and self-incompatibility. It was determined that the pollination of F. michailovskyi mostly depended on pollen vectors, and the effective pollinators of F. michailovskyi were Apis mellifera and Bombus terrestris. In addition, average seed number, seed germination, and average seed viability were found as 144, 46%, and 67%, respectively. The stigma receptivity, pollen grains, and pollen viability were detected as 83%, 252,000, and 95%, respectively. Our study is the first report providing a detailed explanation of the reproductive strategy of this rare endemic species, which could aid in the genetic evolution and conservation of this valuable taxa.

Reproductive Biology of Fritillaria aurea Schott (Liliaceae), a Rare Species Endemic to Turkey

Fritillaria aurea, unlike other Fritillaria species, is a narrowly endemic species. It has a brown checkered speckled color on each tepal and also has regular yellow intense colors on the tepals. Its large bell-shaped appearance when the flower is open is one of its most striking ornamental features. However, F. aurea plant numbers are limited in their natural habitats, and their numbers are decreasing day by day; they are even confronted with the risk of extinction owing to the damage resulting from human activities. This detailed investigation of reproductive biology plays a vital role in determining the evolutionary success and survival of F. aurea, largely in determining the effectiveness of their reproductive performance. Our results indicate that the species exhibits a very low partial dichogamy and herkogamy structure, as well as self-incompatible pollination. The flowering period ranges from March to April. Average seed viability, average seed number, and seed germination were determined as 71%, 255, and 45%, respectively. The pollen viability, pollen grains, and stigma receptivity were found as 96%, 392.000, and 85%, respectively. The pollen/ovule ratio (P/O) and self-incompatibility index (SII) in the spontaneous cross-pollination were detected as 1537 and 0, respectively. Flowers of F. aurea were visited by several insect species, mostly honeybees (Apis mellifera); Bombus sp. and Vespa sp. also played a minor role in pollination. To sum up, these results not only lay a solid foundation for further reproductive biology investigations to more broadly reveal the mechanisms of F. aurea endangerment in the future but also provide a reliable theoretical basis for hybridization breeding of parents.

Jose, K. Subin, T.V. Sarath. Reproductive biology of two threatened and highly traded medicinal plants, Salacia gambleana and Salacia oblonga, from the Western Ghats of India

Salacia is a genus of flowering plants in the family Celastraceae, consisting of woody climbers distributed in tropical America, Africa, and Asia. In India it is represented by 21 species, of which 15 occur in peninsular India. Most species of the genus have been used in traditional medicine, mainly the Ayurvedic system. Apart from overexploitation for medicinal purposes, the low fruit set and infestation of seeds have affected natural regeneration, and led to the rarity of Salacia species in their natural habitats. The reproductive biology of Salacia oblonga and S. gambleana was studied for the first time to understand the reproductive constraints of these threatened and medicinally important species. The flowering phenology, pollen viability, germination, stigma receptivity, and insect-pest interaction were analyzed. The obligatory entomophily coupled with insufficient pollinators and seed pest infestation were found to be the main reproductive constraints responsible for the low fruit set and poor natural regeneration of these species.

Reproductive Biology of Rheum webbianum Royle, a Vulnerable Medicinal Herb From Alpines of North-Western Himalaya

Information on reproductive biology and pollination ecology studies of threatened plants are essential to develop strategies for their sustainable utilization and effective conservation. As such, these studies were conducted on Rheum webbianum, a high-value "vulnerable" medicinal herb of the north-western Himalaya. This species presents a unique mode of reproductive behavior through the involvement of different floral events, including the movement of reproductive organs. The plants survive extremely cold conditions through underground perennating rhizomes that sprout into juvenile shoots with the onset of the favorable climatic conditions. The peduncle arises from the axils of the radical leaves, bearing a globular collection of densely arranged hermaphrodite flowers with temporally separated male and female phases; the male phase precedes the female phase (protandry). Anther dehiscence and stigma receptivity is post-anthesis. Anthers dehisce longitudinally along margins, liberating a large mass of spherical and tricolpate pollen with spinulose exine. Pollen viability decreased to < 10% on day 9. Pistil is tristylous, with each style terminating into a fan-shaped stigma lobe. The pollen receptive surface of each stigmatic lobe remains incurved at an angle of 360° and shows upward movement after anthesis, forming a funnel-like structure at an angle of 180° with respect to the ovary. Pollination syndrome is ambophilous. Spontaneous autogamy or geitonogamy to a certain extent is achieved in this species due to the arrangement of flowers in the inflorescence and overlapping of male and female reproductive phases among them. Incurved stigmatic lobes and outward movement of stamens too facilitate outcrossing. Pollen/ovule ratio estimates, results of pollination experiments on breeding behavior, outcrossing, and self-compatibility indices demonstrated that plants are self-compatible and cross-fertile.

Actinidia callosa var. callosa suppresses metastatic potential of human hepatoma cell SK-Hep1 by inhibiting matrix metalloproteinase-2 through PI3K/Akt and MAPK signaling pathways

BACKGROUND

Cancer cell metastasis involving multi-step procedures and cytophysiological property changes may make difficult in the clinical management and death rate increasing.

RESULTS

In this study, we first observed that ethyl acetate fraction of Actinidia callosa var. callosa (EAAC) carry out a dose-dependent inhibitory effect without cytotoxicity on the mobility and invasion of highly metastatic SK-Hep1 cells. To investigate the EAAC in cancer metastasis, SK-Hep1 cells were treated with EAAC at various concentrations and then subjected to gelatin zymography, casein zymography and western blot to study the impacts of EAAC on metalloproteinase-2 (MMP-2) and tissue inhibitor of metalloproteinase-1/2 (TIMP-1/2), respectively. Our results showed that EAAC treatment may decrease the expressions of MMP-2 and enhance the expression of TIMP-1/2 in a concentration-dependent manner. EAAC also inhibited effect on the phosphorylation of mitogen-activated protein kinase (MAPK) and phosphatidylinositol-3-kinase/serine/threonine protein kinase [or protein kinase B (PI3K/Akt)] and focal adhesion kinase (FAK).

CONCLUSIONS

These results indicate that EAAC inhibited SK-Hep1 cell of metastasis by reduced protein level of MMP-2 through the suppression of MAPK and FAK signaling pathway and of the activity of PI3K/Akt. These findings suggest that EAAC may be used as an antimetastatic agent.