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Floral diagram of MF flowers of Teucrium capitatum (A, B; side-view) and Origanum syriacum (C, D; side-view). F ¼ Male phase and C ¼ female phase.
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Intermediate individuals (perfect flowers with very high degree of pollen abortion) in a gynodioecious plant species are very rare. A study is made of male-female relationships in each flower type and how floral characters can enhance the avoidance of 'pollen discounting' and 'self-pollination' in two gynodioecious species, Teucrium capitatum and O...
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Context 1
... this period, the flower is totally male and sheds pollen (Fig. 2C). While reaching female sexual maturity, the style increases in size and the stigma branches separate. These two processes take place continuously during the flower's lifetime and coincide with wilting of the stamens, moving outwards towards the exterior of the flower (Fig. ...
Context 2
... this period, the flower is totally male and sheds pollen (Fig. 2C). While reaching female sexual maturity, the style increases in size and the stigma branches separate. These two processes take place continuously during the flower's lifetime and coincide with wilting of the stamens, moving outwards towards the exterior of the flower (Fig. ...
Context 3
... stigmatic branches are unequal, practically closed, and during this period the flower is totally male and sheds pollen (Fig. 2A). After 24 h, the style begins to move into position, becoming erect and starting to spread its stigmatic lobes, coinciding with wilting of the stamens (Fig. 2B). MS flowers show neither protandry nor an initially curved style, but they are totally predisposed from the beginning to receive pollen from another plant. INT flowers are protandrous, but their male phase does not last very long (usually less than 24 h). The inward cur- vature of the style in INT flowers is less pronounced than in MF flowers, and some INT flowers have a style that is almost totally erect (flowers with high levels of anther ...
Context 4
... stigmatic branches are unequal, practically closed, and during this period the flower is totally male and sheds pollen (Fig. 2A). After 24 h, the style begins to move into position, becoming erect and starting to spread its stigmatic lobes, coinciding with wilting of the stamens (Fig. 2B). MS flowers show neither protandry nor an initially curved style, but they are totally predisposed from the beginning to receive pollen from another plant. INT flowers are protandrous, but their male phase does not last very long (usually less than 24 h). The inward cur- vature of the style in INT flowers is less pronounced than in MF flowers, and some INT flowers have a style that is almost totally erect (flowers with high levels of anther ...
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Citations
... However, a slight decrease in pollen viability in the Doodhpathri site (SS-II) can be attributed to fluctuating weather conditions during the reproductive phase of the present species. A decline in pollen viability is a common trait in angiosperms that grow under fluctuating weather conditions (Porch and Jahn, 2001;Rodríguez-Riaño, Dafni, 2007;Wang et al., 2010;Wani et al., 2022b). For S. thomsonii media containing sucrose (10%), boric acid (100 ppm) and calcium nitrate (100 ppm) was found suitable for in-vitro germination of pollen grains. ...
Swertia thomsonii an important medicinal plant of Himalaya is more susceptible to extinction in the scenario of
anthropogenic threats and global climate change. Therefore a detailed study on reproductive biology was undertaken for its conservation and sustainable use. The present study was conducted with the aim to understand
reproductive strategies, breeding behaviour and pollination ecology of this prized, endemic medicinal plant
species. It is a perennial rhizomatous herb growing along an altitudinal gradient of 2550–3400 m a.s.l. The
flowering commences from the month of August and continuous till September. The variation in floral traits was
observed across the altitudinal gradients, which reflects its phenotypic plasticity in these characters that helps
the species to get adapted in different environmental conditions. The pollen viability recorded in three study sites
viz. Gulmarg (SS-I), Doodhpathri (SS-II), Pahalgam (SS-III) was 89.83 ± 3.1, 75.86 ± 5 and 84.5 ± 2.5%
respectively. Stigma becomes receptive 4–5 days after anthesis and reaches its peak on 6–7th day. The presence
of typical floral characteristics such as asynchronous anthesis, conspicuous nectaries, spiny exine of pollen, di-
chogamy, and herkogamy points towards entomophilous and outcrossing nature. Reproductive indices like
outcrossing index (OCI), self-incompatibility index (SI) and selfing rate (S) as well as results of bagging exper-
iments also revealed that the species is self as well as cross-compatible. However, fruit and seed set recorded in
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mode of pollination. Mixed matting is operative in the target plant species, preferring xenogamy followed by
geitonogamy and autogamy. The species is pollinated by specialized pollinators which mostly belong to the
Order Hymenoptera. Suitable media for in-vitro pollen germination has also been identified; the knowledge about
peak stigma receptivity and pollen germination is indispensable for breeding programmes. Thus the scientific
information generated in the present study may prove useful in different breeding programmes and conservation
of this valuable plant species.
... This noticeable variation in viability percentages of pollen grains may be attributed to different Ocimum species and type of stain. Many researchers also showed the efficacy of MTT and TTC stain on pollen viability studies in the Lamiaceae family plants like Teucrium capitatum and Origanum syriacum (Rodríguez-Riaño and Dafni, 2007) and the other plants such as Jatropha curcas (Abdelgadir et al., 2012), Mespilus germanica (Cavusoglu and Sulusoglu, 2013), Prunus laurocerasus (Sulusoglu and Cavusoglu, 2014), Leonurus cardiaca (Shekari et al., 2016) and Litchi chinensis (Gupta et al., 2018). ...
In the present investigation, pollen morphology and viability of four Ocimum L. species viz. O. sanctum (CIM-Angana), O. basilicum (CIM-Saumya), O. gratissimum, and O. kilimandscharicum were studied. Morphological characters were observed using scanning electron and light microscopy. Pollen of all the four studied Ocimum species have hexacolpate apertures with varied aperture length and width. The exine ornamentation was reticulate and bi-reticulate. O. basilicum has large size (53.9 µm) pollen grains and rest three have medium sized pollen. The viability of pollen was assessed through staining dyes such as 2,5-diphenyl tetrazolium bromide (MTT) and 2,3,5-triphenyl tetrazolium chloride (TTC) and in vitro pollen germination method. O. basilicum possessed maximum viability (92.4%) whereas least viability was found in O. sanctum (38.2%). The maximum pollen germination percentage and tube growth were observed in the semisolid medium gelled with phytagel supplemented with 15% sucrose, 15% PEG, 6.4 mM boric acid and 7.3 mM calcium nitrate. O. basilicum showed the highest germination percentage (90.3%) followed by O. kilimandscharicum (57.1%), O. gratissimum (42.5%) and O. sanctum (25.5%). Pollen of the four Ocimum species were stored at different temperatures viz. 37 °C, + 4 °C, 0 °C, − 20 °C, and − 80 °C for 75 days. The highest pollen germinability of all the four Ocimum species was observed at − 20 °C. This study can be helpful in taxonomic identification of Ocimum species and further utilized in conservation and improvement of different Ocimum species by cross-hybridization breeding programmes.
... A slight decrease in the pollen viability at populations of Katarkhal as compared with that of Panikhar can be attributed to the climatic stress induced due to changing weather conditions during the reproductive phase of R. webbianum. Pollen viability declined with the age of flower and such findings are in line with the studies of Mercado et al. (1994) and Rodriguez-Riano and Dafni (2007), who reported a steady decline in pollen viability with the aging of flowers. ...
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.
... In addition, style length in S. graminea was larger in females compared to hermaphrodites, again irrespectively of the ploidy level. Such an increase in size is not rare in gynodioecious females and can be explained by the compensatory relocation of resources to female functions (e.g., Rodríguez-Riaño and Dafni, 2007;Miller et al., 2016). The longer style in females might increase the flower's visibility despite the smaller size of its corolla, improving female reproductive success. ...
Plant speciation results from intricate processes such as polyploidization, reproductive strategy shifts and adaptation. These evolutionary processes often co-occur, blurring their respective contributions and interactions in the speciation continuum. Here, relying on a large-scale study, we tested whether gynodioecy triggers the divergent evolution of flower morphology and genome between sexes, and contributes to the establishment of polyploids and colonization of ecological niches in Stellaria graminea. We found that gynodioecy in S. graminea leads to flower morphology divergence between females and hermaphrodites, likely due to sexual selection. Contrary to our expectations, gynodioecy occurs evenly in diploids and tetraploids, suggesting that this reproductive strategy was not involved in the establishment of polyploids. Both diploid and tetraploid females have a larger genome size than hermaphrodites, suggesting the presence of sex chromosomes. Finally, ecology differs between cytotypes and to a lesser extent between sexes, suggesting that the link between environment and presence of females is indirect and likely explained by other aspects of the species’ life history. Our study shows that gynodioecy leads to the consistent evolution of sexual traits across a wide range of populations, cytotypes and environments within a given species, and this likely contributes to the phenotypic and genetic distinctiveness of the species from its sister clades.
... Some studies have also investigated the variation of floral construction in different flower morphs related to the breeding system and the evolution of separate sexes in gynodioecius Teucrium species (Puech 1978;El Oualidi 1987;Alados et al. 1997;Rodríguez-Riaño and Dafni 2007) and Teucridium genus (Merrett 2005). ...
The generative morphology related with corolla and calyx construction, pollen, inflorescence type and nutlets are of great importance in Teucrium L. These characters are the basis for the classic systematic and recent classifications. Teucrium has a corolla usually 1-lipped or 2-lipped (bilabiate). Spartothamnella Briq., Oncinocalyx F. Muell., and Teucridium F. Hook, closely related to Teucrium, present a corolla 5-lobed in the upper half, lobes slighty spreading, 4 posterior ± similar, anterior lobe larger than the others and not concave. The calyx in these genera is actinomorphic. This is an exceptional corolla conformation in Teucrium and only found in these species. The main difference between Spartothamnella and Teucrium is that the former has drupaceous fruit and between Teucrium and Teucridium is the ovary form. Oncinocalyx differs from Teucrium in the conspicuously hooked calyx lobes. Teucrium Sections Pycnobotrys Benth., Stachyobotrys Benth., Scorodonia (Hill) Schreb., and Teucriopsis Benth., have weakly 2-lipped corolla and zygomorphic calyx. Species of section Teucrium have 1-lipped spurred corolla and actinomorphic calyx except for the Australian species with non-spurred corollas. Teucrium show a great diversity in floral phenotypic diversity and adaptive significance to pollination and dispersal. Functional redundancy is found in the gullet-shaped corollas with nectar guides and nototribic pollination of the sections Chamaedrys (Mill.) Kästner, lsotriodon Boiss., subsection Scordium (Mill.) Kästner, Montana Lazaro Ibiza and subsection Pumila (Lazaro Ibiza) Rivas Mart. Teucrium is the only genus within the sub family Ajugoideae with two derived pollen characteristics, granulate or verrucate sculpturing and operculate colpi and with a considerable variation in pollen sculpturing. Nototribic pollination of the gullet-shaped corollas with closed gullet mechanism (by a palate of hairs associated to a slight pouch in the corolla tube) are exclusive of the section Teucrium. The sternotribic pollination of the brush-shaped corollas closed by a tuft of hair in the entrance of the corolla tube (base of the anterior lobe), are specific of the ginodioecious species of section Polium (Mill.) Schreb. Resupinate flag-shaped corollas with sternotribic pollination is present in subsection Spinularia (Boiss.) Kästner and Stachyobotrys. The main dispersal modes in section Chamaedrys, lsotriodon and Polium is the semachory. Sections Teucrium and Teucriopsis are wind-dispersal by pogonospores, subsection Spinularia, section Scorodonia and Teucrium betonicum and Teucrium abutiloides L’Hér from section Teucriopsis are ballospores.
... In gynodioecious species, hermaphrodite plants act as pollen donors and can contribute to the next generation with both the female and male functions (Charlesworth and Charlesworth 1987). Unlike female plants, hermaphrodites can suffer inbreeding depression and pollen-stigma interferences (Harder and Wilson 1998;Barrett 2002;Rodriguez-Riaño and Dafni 2007), and in order to reduce these risks, dichogamy (the temporal separation between the maturation of anthers and stigma within the flower) and/or herkogamy (the spatial segregation of male and female functions within the flower) can be present in hermaphrodite flowers (Lloyd and Webb 1986;Bertin and Newman 1993;Barrett 2002). Meanwhile, female plants can only transmit their genes through the production of ovules. ...
... Hermaphrodite flowers showed protandry and approach herkogamy produced by the elongation of the style (the stigma when opened is located above the anthers). Style elongation, as well as the presence of dichogamy and herkogamy within a flower, have been already described in other gynodioecious species of Lamiaceae and could represent a successful combination of strategies to avoid autonomous self-pollination (Thompson and Taraire 2000;Thompson et al. 2002;Hong and Moon 2003;Rodriguez-Riaño and Dafni 2007). Surprisingly, the styles of female flowers remain closed during the first day of floral anthesis, as in hermaphrodites. ...
Minthostachys (Benth.) Spach (Lamiaceae) is one of the most important genus in Andean folk medicine. Minthostachys species are harvested in the wild rather than cultivated. Beyond the key socio-cultural role of these species, there have been no studies to evaluate their reproductive requirements as part of their conservation. M. verticillata is a gynodioecious species endemic from Argentina, whose populations are threatened because of overexploitation and habitat loss. The level of reproductive dependence on animal pollination, the diversity and composition of floral visitors’ assemblages, flower morphology, fruit and seed set and the progeny vigour of female and hermaphrodite plants were evaluated. Both sex morphs rely absolutely on animal pollination for seed production and were visited by a similar and diverse assemblage of insects (Diptera, Lepidoptera and Hymenoptera); however, the tachinind fly Ptilodexia cf. cingulipes was the main pollinator. Female plants have smaller flowers, higher fruit set, fruits with more seeds, and a higher percentage of seed germination than hermaphrodites. There were no differences in growth rate and biomass of seedlings produced by female and hermaphrodite plants. Lower reproductive success of hermaphrodites could be due to self-incompatibility or inbreeding depression. These results suggest that it is a fragile system where hermaphrodite plants perform mainly as pollen donors, females as seed producers, and seed production relies almost exclusively on a native tachinid species, which is furthermore parasitoid. This knowledge can be applied in conservation programs in order to promote the sexual reproduction and so the conservation in situ of this key medicinal resource.
... Moreover, S. pratensis is a gynodioecious species, consisting of two different flower morphs. The size difference between hermaphroditic (or male fertile) and female (or male sterile) flowers have been reported for several Salvia species and other taxa from Lamiaceae (Plack 1957;Delph 1996;Claßen-Bockhoff et al. 2004;Rodríguez Riaño & Dafni 2005;Takano et al. 2013). For S. pratensis, Delph (1996) reported size differences between the two flower morphs, with female flowers being smaller. ...
Classical and geometric morphometric analyses of floral characters of Salvia pratensis agg. were performed on populations from the E Adriatic area. Both types of analyses yielded congruent results, and three groups of populations, attributed to S. verbenaca, which served as an outgroup, S. saccardiana and S. pratensis (incl. S. bertolonii), were unambiguously identified. Results confirmed floral size dimorphism, with hermaphroditic flowers being significantly bigger than female ones, while we newly identified floral shape dimorphism in S. pratensis, too. No gynodioecious populations were observed in morphologically otherwise very uniform S. saccardiana. Being a SE Alpine endemic, the latter was for the first time recorded in Croatia. While S. saccardiana merits species rank, we found no support for the segregation of S. bertolonii and S. pratensis. Clinal variation in floral characters of S. pratensis, generally detected in populations of various taxa along the E Adriatic coast, lacks the spatial consistency and geographic pattern that would allow for a clear delimitation of S. pratensis and S. bertolonii.
... Protandry is common, and self-pollination is therefore almost impossible. Geitenogamy and cross-pollination are dominant in the family (Hidalgo and Ubera, 2001;Rodriguez-Riano and Dafni, 2007). ...
... The reproductive biology of several species of Lamiaceae has been widely studied; for example, Origanum majorana and Teucrium capitatum (Rodriguez-Riano and Dafni, 2007), Rosmarinus officinalis (Hidalgo and Ubera, 2001), S. smyrneae (Subashi and Guvensen, 2011), and Monarda fistulosa (Cruden et al., 1984). However, little is known about the genus Leonurus. ...
... To avoid self-pollination, a negative correlation between stigma receptivity and pollen viability exists in protandrus species, although it cannot prevent the pollination of the flower by pollens of the other flowers on the same plant (geitenogamy). Rodriguez-Riano and Dafni (2007) pointed out that in Origanum syriacum, self-pollination is avoided by dichogamy (a negative correlation between stigma receptivity and pollen viability), and the style length is significantly positively correlated with stigma receptivity. (Table 4). ...
... Outra hipótese seria a existência de mecanismos biológicos intrínsecos (eg. Competição do grão de pólen no estilete;Seleção sexual direcionada a tubos polínicos ágeis; Stigma clogging) que impeçam a inviabilidade ou o "entupimento" do estilete, impedindo a passagem dos tubos homoespecíficos ao óvulo, ou melhorando o desempenho germinativo de grãos homoespecíficos / tubos no gineceuRodríguez-Riaño & Dafni 2007;Herbertsson & Smith 2017).Uma terceira hipótese pode ser levantada sobre esta relação: Seria a autogamia uma resposta a competição e ao fluxo polínico resultante entre este par de espécies? Testar esta hipótese envolve estudos com várias populações, tanto alopátricas quanto simpátricas, uma vez que a distribuição dos sistemas reprodutivos parece evoluir de acordo com a seleção pela qual as populações passam(Jain 1976; Endress 1994;Matallana et al. 2010;Zanella et al., 2012;Fallis 2013).Embora as espécies autoincompatíveis em Bromeliaceae não aceitem positivamente a autozigose, grande parte dessas espécies apresentam maior capacidade de congruência congenéricas e infragenérica(Matallana et al. 2016;. ...
Bromeliaceae is a group of neotropical monocotyledons with 3543 species in 73 genera.
Recognized as one of the most notorious cases of adaptive radiation, it has a large variety of reproductive traits. However, several correlated bromeliads occur in sympatry, and to allow this, there must be strong reproductive barriers that keep these species cohesive. This dissertation aimed to describe the reproductive biology of two sympatric bromeliads in the Atlantic Forest of Rio Grande do Norte, in order to understand how reproductive dynamics occurs and the mechanisms that allow the cohesion of both, by analyzing the pollen flow and reproductive barriers. This work was carried out in the Nísia Floresta National Forest, a fragment of Atlantic Forest in the state of Rio Grande do Norte, and the species sampled were Wittmackia patentissima and Hohenbergia ridleyi. In Chapter I, the processes involving reproductive biology, pollination ecology and floral phenology of Wittmackia patentissima and Hohenbergia ridleyi, were analyzed, trying to describe their respective reproductive mechanisms, as well as possible pre-pollination barriers and the pollen flow between them. We found that both have delicate, aromatized, diurnal, flowers that are available for 1-2 days. In addition, flowering is synchronous, occurring between August and October, with several individuals overlapping and prolonging the reproductive season. The main floral visitors are bees, but other hymenoptera, lepidoptera, coleoptera and diptera can be seen, all of which use floral nectar as a resource. Basically, all the floral characteristics are shared, not being identified any type of reproductive barrier of the type pre-pollination between them. In Chapter II, the reproductive systems of this pair of species were described, in order to understand how the dynamics of pollination occurs and what mechanisms enable fruiting. In addition, hybridization tests were performed between these species, analyzing the growth of the pollen tube along the gynoecium, to observe if there are post-pollination barriers that prevent the formation of natural hybrids. As a result, it has been found that both taxa are highly self-compatible, and that there is spontaneous pollen deposition while in flower bud stage, and this can maximize their
reproductive success. In the hybridization tests it was possible to observe that the pollen grains germinated and grew until the first portion of the style in all treatments in both species. There was no difference in pollen development in the self- versus cross pollination treatments for either species, however, it was possible to observe abnormalities from the second portion of the style in the hybridization tests. At this point, it was possible to observe the irregular deposition of callose along the style, as well as the stoppage of the pollen tubes in all the hybridization tests, indicating that there are strong post-pollination barriers that inhibit the formation of natural hybrids.
... Anthesis is obviously asynchronous from plant to plant, capitulum to capitulum and floret to floret. It is stressed that pollen viability decreases over time, whereas stigma receptivity increases in protandric species (Rodriguez-Riano and Dafni, 2007). Similar results of protandrous have been observed in previous studies (Young et al., 2002;Wani et al., 2006). ...
Centaurea amaena is an endemic plant species that is under critical risk of extinction and was known from only one population in Kayseri, Turkey. During our research another locality was found at about 15 km distance from the first known population. In this study, the population pattern of this species and its distribution, the reasons for its narrow range, its pollen viability, stigma receptivity, and the breeding system have been identified, and practical efforts have been carried out for conservation. Pollination experiments showed that C. amaena pollination mechanism allows first for allogamy and then secondary pollen presentation and that the timing pollen viability and stigma receptivity are asynchronous. The seed-to-ovule ratio was calculated as 35%. According the tetrazolium staining viability test, the seed viability also was determined as 82.6%. The main factor threatening the species were identified to be anthropogenic-related (including construction, over -grazing, tourism), and some strategies have been developed for the purpose of conservation it. © 2018, Pakistan Agricultural Scientists Forum. All rights reserved.
