Seed coat structure ofCrocus vernus agg. (Iridaceae)

Cytotypes of theCrocus vernus aggregate differ slightly in their seed surface patterns.Crocus albiflorus may be grouped together withCrocus vernus subsp.vernus, both are relatively easily distinguishable by their seed surface patterns from theCrocus scepusiensis—Crocus heuffelianus group.     

Crocus demirizianus sp. nov. from northwestern Turkey

A new species, Crocus demirizianus O. Erol & L. Can is described and illustrated from northwestern Turkey. Crocus demirizianus was found in the Çanakkale province, near the district of Çan, and is undoubtedly related to the Crocus biflorus complex. However, the species differs from its relatives by typically sagittate anthers, and flowers without prominent stripes on outer segments. Diagnostic morphological characters are discussed and high resolution images are presented.     

Crocus cancellatus subsp. damascenus stigmas: chemical profile,and inhibition of α-amylase, α-glucosidase and lipase,key enzymes related to type 2 diabetes and obesity

Spices are appreciated for their medicinal properties besides their use as food adjuncts to enhance the sensory quality of food. In this study, Crocus cancellatus subsp. damascenus was investigated for its antioxidant activities employing different in vitro systems. Stigma extract demonstrated a radical scavenging activity against both 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radicals with IC₅₀ values of 34.6 and 21.6?µg/mL and a good ferric reducing ability (53.9?µM Fe(II)/g). In order to clarify the potential functional properties of this spice, the carbohydrate-hydrolysing enzymes and pancreatic lipase inhibitory properties were investigated. Crocus cancellatus subsp. damascenus extract inhibited α-amylase and α-glucosidase with IC₅₀ values of 57.1 and 68.6?µg/mL, respectively. The bioactivity was discussed in terms of phytochemicals content. The obtained results may be of interest from a functional point of view or as food additive and to promote the revalorization of this species.     

Flow cytometric analysis of nuclear DNA inCrocus sativus and allies (Iridaceae)

The genome size and base composition of the triploidCrocus sativus and its two diploid most probable ancestors,C. cartwrightianus andC. thomasii, was investigated and compared inter- and intra-specifically by means of flow cytometry. There was little variation inC. sativus and little difference fromC. cartwrightianus. Crocus thomasii was significantly different from the others.Crocus cartwrightianus is the most probable diploid ancestor ofC. sativus.     

Chromosomal differentiation withinCrocus vernus agg. (Iridaceae) in the Carpathian Mts.

Western and eastern Carpathian populations ofCrocus heuffelianus s. lat. (incl.C. scepusiensis) have 2n = 18 but differ in karyotype. While western populations are chromosomally monomorphic, eastern populations exhibit geographical karyotypic differentiation.     

Ultrastructure and Germination Percentage of Crocus biflorus Miller subsp. biflorus (Iridaceae) Pollen

Pollen of Crocus biflorus Miller subsp. biflorus from natural habitats of Tusculum (Frascati, near Rome, Italy) has been studied in order to compare its structure and physiology to pollen of other Crocus species belonging to the Crocus sativus group. Mature pollen grains are rounded, 60 μm in diameter, in-aperturate (but with surface incisions where exine is lacking). DAPI staining reveals a spindle-shaped generative nucleus which is intensely fluorescent, and vegetative nucleus which is less fluorescent, and is elongated with numerous lobes. At anthesis the pollen is bicellular, but about 2% of tricellular grains occur among the pollen grains released from the anthers as well as on both naturally or handpollinated stigmas. Pollen germination is low in vitro, but higher in vivo. The pollen tubes are of normal shape. An electron-dense surface coat is sometimes visible on the exine, which in many cases, is detached from the exine. The vegetative cytoplasm is very rich in glycolipid bodies surrounded by endoplasmic reticulum. The generative cell has a lobed cell wall and is surrounded by the vegetative nucleus.     

Crocus antalyensis subsp. striatus subsp. nov. (Iridaceae) from southwest Anatolia

A new subspecies Crocus antalyensis subsp. striatus subsp. nov. from western Turkey is described. It is characterized by rough papery, light brown corm tunics, leaves that exceed the flower at anthesis and are recurved, distinctly striped inner perianth segments and deeply branched pale yellow or white style. The karyotype of the new subspecies is presented.     

In vitro development of parthenocarpic fruits of Crocus sativus L.

In vitro development of parthenocarpic fruits of Crocus sativus L. was induced by culturing ovaries on MS agar medium supplemented with growth-regulators (2,4-D, GA₃ and BAP). Amongh these, 2,4-D was the most effective in promoting fructification. The fructigenic activity was independent of both the stage at which the ovaries were excised (before, during or after anthesis) and pollination of the stigmas. Unlike the above compounds, abscisic acid inhibited fructification.     

Pregamic and postgamic self-incompatibility systems inCrocus (Iridaceae)

Ovule fertilization and seed set were investigated inCrocus thomasii andCrocus vernus subsp.vernus, after different matings. The results gave evidence for a strict ovarian barrier inC. thomasii, which prevents self-fertilization either in self- or mixed- and double-pollination. InC. vernus the ovarian barrier to selfing is not so effective, but a further incompatibility reaction is expressed after self-fertilization resulting in a complete failure of embryogenesis. The implications of the present observations in respect to the mechanisms of pregamic- and postgamic rejection, indicate that a gametophytic system of self-incompatibility controls the ovule fertilization, and a not yet defined system of self-incompatibility controls embryogenesis.     

Comparative effects of nitric oxide and salicylic acid on salinity tolerance in saffron (Crocus sativus)

Abstract

Salinity is a major environmental stress worldwide that adversely affects plant’s growth and metabolism. Various studies have demonstrated the positive effect of growth regulators on improving stress tolerance of plants. In this study, Crocus sativus as a profitable herb and expensive spice was subjected to nitric oxide and salicylic acid treatments to improve its sustainability under salinity stress. Based on our results treating Crocus sativus corms with nitric oxide caused more growth under salinity stress, also nitric oxide was able to reduce stress effects by compatible solutes accumulation, inducing antioxidative enzyme activities and increasing the biosynthesis of secondary metabolites. However, salicylic acid treatment did not improve plant growth under salinity.     

RAPD Analysis in Crocus sativus L. Accessions and Related Crocus Species

In the present paper a Random Amplified Polymorphic DNA (RAPD) investigation was carried out on DNAs from five Crocus sativus L. (saffron) accessions cultivated in different countries and on six closely related Crocus species. Aims of the study are to check whether cultivated saffron has maintained a constant genomic organisation and to clarify its relationships with possible ancestor species. For the fifteen primers, which produced positive results, DNAs of saffron corms from different accessions present the same amplification pattern, in accordance with the similar DNA content and base composition pointed out in previous studies. The amplification of the seven Crocus species DNAs with twenty-one primers provided 217 repeatable and interpretable fragments, which were scored for presence/absence and employed for a cluster analysis. Results indicated that C. sativus is very closely related to C. cartwrightianus and also similar to C. thomasii. This result, concurring with part of the previous evidence, would rule out the hypothesis of close relationships between C. sativus and C. pallasii.     

Crocus imperati and Crocus suaveolens (Iridaceae), two controversial endemic crocuses from Central and Southern Italy – morphometrics,lectotypification and chorology

Crocus imperati Ten. and Crocus suaveolens Bertol. are the most controversial endemic crocuses in Italy; they have been interpreted by various authors as different species or infraspecific entities and their chorologies are afflicted by numerous misidentifications. This work, by means of an extensive in vivo study across the whole ranges of the two taxa, and using biometrical investigations, aims at clarifying their status. The names C. imperati and C. suaveolens are typified, several taxonomical complications are discussed and an accurate chorology is outlined. The results show that a single qualitative character is constant (the presence or absence of a bracteole) and two other characters allow discrimination in most cases; their combined use, therefore, ensures certain identification of any single individual. No hybrid individual or intermediate populations were detected and the distributional ranges of the two species were confirmed to be contiguous but not overlapping. As a consequence, treatment of the two taxa at specific level appears to be the most appropriate. © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 158 , 194–214.     

A contribution to the karyology ofCrocus vernus agg. (Iridaceae) from the Iserian Mts. (Sudety Mts., Poland)

The Iserian Mts. form ofCrocus vernus agg. has 2n = 16 and a karyotype clearly deviating fromC. heuffelianus s. lat.     

Germination and viability of the pollen of Crocus sativus L

Abstract

Viability and germinability tests were carried out on the pollen of Crocus sativus L., a sterile triploid commonly known as saffron. Pollen taken from dehiscent anthers was examined by means of vital staining and cytochemical techniques in order to detect its viability; germination in vitro was evaluated. From the results obtained it is evident that saffron pollen is viable at a high percentage (65%) but germinates at a very low percentage. Moreover in vitro germination is very slow, and is accompained by numerous morphological anomalies. The low germination of the pollen is due to the triploidy of C. sativus.     

Bioactive compounds of Crocus sativus L. and their semi-synthetic derivatives as promising anti-Helicobacter pylori,anti-malarial and anti-leishmanial agents

Abstract

Crocus sativus L. is known in herbal medicine for the various pharmacological effects of its components, but no data are found in literature about its biological properties toward Helicobacter pylori, Plasmodium spp. and Leishmania spp. In this work, the potential anti-bacterial and anti-parasitic effects of crocin and safranal, two important bioactive components in C. sativus, were explored, and also some semi-synthetic derivatives of safranal were tested in order to establish which modifications in the chemical structure could improve the biological activity. According to our promising results, we virtually screened our compounds by means of molecular modeling studies against the main H. pylori enzymes in order to unravel their putative mechanism of action.     

Strukturen endopolyploider Kerne im Bereich der Samenanlage einiger Monocotylen

Zusammenfassung Die Kerne der Antipoden vonHyacinthus orientalis (Kulturformen) undCrocus suaveolens wachsen endomitotisch heran und werden bei der erstgenannten Art schätzungsweise bis zu 32ploid, bei der anderen bis zu 64ploid.In diploiden sowie hypertriploiden Pflanzen vonHyacinthus sind zwei Strukturtypen der endopolyploiden Kerne vorhanden, und zwar solche mit gleichmäßiger Struktur und andere mit lockeren Bündeln von Endochromosomen. Im Nukleolus der Antipoden diploider Pflanzen tritt ein einziges wurstförmiges Endochromozentrum hervor; in den 1 oder 2 Nukleolen der hypertriploiden Pflanzen sind 2 solche Endochromozentren vorhanden.Die Kerne der endopolyploiden Antipoden vonCrocus suaveolens zeigen in einer euchromatischen Grundstruktur langgestreckte Endochromozentren, von denen eines in Verbindung mit dem Nukleolus steht. An diesem Nukleolus-assoziierten Endochromozentrum finden sich in manchen Kernen unmittelbar neben dem Hauptnukleolus zusätzliche kleine Nukleolen in verschiedener Zahl.Im Basalapparat des Endosperms vonAllium ursinum wurden in Kernen verschiedener Polyploidiegrade neben den bereits angegebenen Strukturen vereinzelt Riesenchromosomen beobachtet. Sie zeigen den charakteristischen Chromomerenbau.BeiNothoscordum fragrans geht das Kern Wachstum in den Synergiden, in den Antipoden und im Basalapparat des Endosperms endomitotisch vor sich. Die Biesenkerne des Endosperms zeigen Bündel von Endochromosomen mit Restspiralen.

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Summary The nuclei in the antipodals ofHyacinthus orientalis (cultivated forms) andCrocus suaveolens increase by endomitotic polyploidization; their highest degree of endopolyploidy is approximately 32 n inHyacinthus and 64 n inCrocus.In diploid as well as in hypertriploid plants ofHyacinthus two structural types of endopolyploid nuclei occur, viz. nuclei with equally distributed chromatin and others with loose strands obviously consisting of several to many endochromosomes. Within the nucleolus of the antipodals of diploid plants a single oblong chromocentre occurs, while in the 1 or 2 nucleoli of hypertriploids two such endochromocentres are regularly encountered.InCrocus suaveolens the nuclei of the endopolyploid antipodals show several oblong chromocentres together with the uniform euchromatic structure; one of them is connected with the nucleolus. In some nuclei this SAT-endochromocentre produces in close vicinity of the big main nucleolus additional small nucleoli in various number.As previously described, the basal apparatus of the endosperm ofAllium ursinum contains nuclei of various degrees of endopolyploidy; besides other well-known structures they show sporadically giant chromosomes with the characteristic chromomeric constitution.InNothoscordum fragrans the nuclei of the synergids, as well as those of the antipodals and the basal apparatus of the endosperm enlarge by endomitotic polyploidization. The giant nuclei of the endosperm show complex strands of endochromosomes with relic spirals.

     

The avoidance of self-interference in the Tuscan endemic spring geophyte Crocus etruscus Parl. (Iridaceae)

Spatial separation between sexes within hermaphrodite flowers (herkogamy) is widespread among angiosperms and is traditionally viewed as an adaptation that reduces the likelihood of self-pollination. While different degrees of herkogamy have been reported for Crocus, the relationship between sexual organ positions and reproductive fitness has not been explored yet, and studies of the breeding system within natural populations remain scarce within the genus. We analyzed the effects of different breeding systems (spontaneous self-pollination, facilitated self-pollination and cross-pollination) and of herkogamy degree on female reproductive success of the Tuscan endemic Crocus etruscus. Results showed that C. etruscus is monomorphic for style length and self-incompatible (SCI = 0.29). We also detected a significant negative effect of herkogamy on seed set of open-pollinated flowers. Thus, we conclude that the species avoids self-fertilization by self-incompatibility, but interestingly shows also a certain degree of spatial separation of male and female reproductive structures within the same flower. This floral trait could be useful to avoid self-interference thus reducing ovule discounting and pollen loss on its own stigma.     

Embryo origin and development in Crocus sativus L. (Iridaceae)

Abstract

Fruit and seed set were obtained in the triploid Crocus sativus (saffron) either by hand crossing with pollen of the diploid C. cartwrightianus or by free pollination. The morphology of the capsules and seeds was similar in both Crocus species. The embryo is comparatively small, whereas the endosperm is formed of numerous layers of cells with hemicellulose-thickened walls and a cytoplasm containing few lipid and protein reserves. Seed germination gave rise to a white prophyll from which a green leaf emerged. At the base of this leaf, a small corm without tunics developed, which, after leaf desiccation, became dormant. These corms sown separately in pots were again capable of growth and emitted a single long green leaf. Vegetative development of new corms was similar in the diploid and hybrid saffron plants. In sites of past saffron cultivation the beds were found to contain degenerated corms and corms at different development stages. The absence of fruit and seed set in emasculated and self- and out-pollinated plants suggests that saffron does not form apomictic embryos.