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Paulo Eugênio Oliveira - One of the best experts on this subject based on the ideXlab platform.
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Polyembryony in Melastomataceae from Brazilian Cerrado: multiple embryos in a small world
Plant biology (Stuttgart Germany), 2012Co-Authors: Clesnan Mendes-rodrigues, Paulo Eugênio OliveiraAbstract:Polyembryony has been commonly associated with apomixis in the angiosperms and seems to be more common than expected, even in biomes where sexual reproduction processes are predominant. Recent studies in Cerrado, the Neotropical savannas of Central Brazil, showed high frequencies of apomixis and Polyembryony and indicated these processes as reproductive and evolutionary alternatives for plants in these areas. In this sense, we investigated the occurrence of Polyembryony and its relationships with ecological (season and type of dispersal, ploidy, species distribution and breeding system) and taxonomic (tribe) factors in the Melastomataceae, a mostly tropical family already known for its high frequency of apomixis and very common in Cerrado. We collected seeds from 69 populations of 53 species, which were sown in germination chambers. After seed germination, the presence and number of seedlings per seed were evaluated as a method to estimate Polyembryony. We encountered 18 species (33.96%) with Polyembryony (more than one seedling, or gemellar seedlings, originated per seed) concentrated in species of the tribe Miconieae (64%) and Microlicieae (16.67%), but absent in Melastomeae. Monoembryony was present only in sexual species, while all apomictic species were polyembryonic. In Miconia, the Polyembryony was correlated with polyploidy, and monoembryony with diploid species. Polyembryony was more common among species with wide distribution in the Cerrado region, which indicates that the presence of gemellar seedlings is important for establishment and survival of the group in the Cerrado biome.
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Polyembryony increases embryo and seedling mortality but also enhances seed individual survival in Handroanthus species (Bignoniaceae)
Flora - Morphology Distribution Functional Ecology of Plants, 2012Co-Authors: Clesnan Mendes-rodrigues, Marli A. Ranal, Diana Salles Sampaio, Maria Eugênia Costa, Ana Paula Souza Caetano, Nelson Sabino Bittencourt Júnior, Paulo Eugênio OliveiraAbstract:a b s t r a c t Polyembryony seems to be advantageous to mother plants in detriment of their siblings which face com- petition since the beginning of seed development. This competition may limit the turnover of embryos into seedlings and their survival ability. We analysed Polyembryony frequency and embryo to seedling turnover in three Handroanthus species with sporophytic apomixis. We tested if the embryo number per seed affected seed and embryo morphometry, seedling survival ability and seed individual survival (i.e. survival of at least one seedling per seed). The number of embryos per seed was compared with seedling number at different developmental stages. All 14 populations showed high frequencies of polyembry- onic seeds (21-91%). As the number of embryos per seed increased (up to eight embryos/seed), there was a reduction of mean embryo mass, area, seedling length, individual seedling survival ability, and embryo to seedling turnover. There was also an increase in embryo morphological anomalies. However, enhanced seed individual survival was also observed. Thus, the high frequency of polyembryonic seeds and the increase in seed individual survival support the idea that Polyembryony represents an alternative reproductive mechanism which can favours these species.
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does Polyembryony reduce seed germination and seedling development in eriotheca pubescens malvaceae bombacoideae
American Journal of Botany, 2011Co-Authors: Clesnan Mendesrodrigues, Marli A. Ranal, Paulo Eugênio OliveiraAbstract: Premise of the Study: Competition between siblings affect their growth and survival ability. An extreme situation is Polyembryony, whereby siblings are exposed to competition from the beginning of their development. But its effect on plant reproduction is seldom tested. Eriotheca pubescens is a tree in the Cerrado, the Neotropical Savannas in Brazil, with apomictic/ polyembryonic and sexual/monoembryonic populations. We tested the effect of Polyembryony on germination, emergence, and growth in E. pubescens . This may have ecological consequences within the Cerrado, where seedling establishment is critical for species persistency and distribution. Methods: We tested the effect of embryonic origin on germinability- and time-related parameters using seeds from different populations. We measured cultivated seedling growth continuously for 70 d and exhumed them after 9 mo to measure seedling biometry traits such as shoot, root, and seedling mass. We compared these traits with the number of seedlings emerged per seed and fi tted data to a linear regression model. Key Results: Polyembryony reduced germinability and seedlings ’ initial growth in E. pubescens . Seedling traits and biomass decreased with the number of seedlings arising per seed. But the effect of Polyembryony was mostly on initial seedling size and not on seedling growth rate. Conclusions: Polyembryony and apomixis affected germination and led to smaller seedlings compared with monoembryonic sexual counterparts. Although smaller, these extra seedlings may enhance per-seed survival chances in the Cerrado conditions of seasonal drought and frequent fi res and explain the predominance of polyembryonic populations.
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Does Polyembryony reduce seed germination and seedling development in Eriotheca pubescens (Malvaceae: Bombacoideae)?
American journal of botany, 2011Co-Authors: Clesnan Mendes-rodrigues, Marli A. Ranal, Paulo Eugênio OliveiraAbstract: Premise of the Study: Competition between siblings affect their growth and survival ability. An extreme situation is Polyembryony, whereby siblings are exposed to competition from the beginning of their development. But its effect on plant reproduction is seldom tested. Eriotheca pubescens is a tree in the Cerrado, the Neotropical Savannas in Brazil, with apomictic/ polyembryonic and sexual/monoembryonic populations. We tested the effect of Polyembryony on germination, emergence, and growth in E. pubescens . This may have ecological consequences within the Cerrado, where seedling establishment is critical for species persistency and distribution. Methods: We tested the effect of embryonic origin on germinability- and time-related parameters using seeds from different populations. We measured cultivated seedling growth continuously for 70 d and exhumed them after 9 mo to measure seedling biometry traits such as shoot, root, and seedling mass. We compared these traits with the number of seedlings emerged per seed and fi tted data to a linear regression model. Key Results: Polyembryony reduced germinability and seedlings ’ initial growth in E. pubescens . Seedling traits and biomass decreased with the number of seedlings arising per seed. But the effect of Polyembryony was mostly on initial seedling size and not on seedling growth rate. Conclusions: Polyembryony and apomixis affected germination and led to smaller seedlings compared with monoembryonic sexual counterparts. Although smaller, these extra seedlings may enhance per-seed survival chances in the Cerrado conditions of seasonal drought and frequent fi res and explain the predominance of polyembryonic populations.
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Polyembryony and apomixis in Eriotheca pubescens (Malvaceae - Bombacoideae).
Plant biology (Stuttgart Germany), 2005Co-Authors: Clesnan Mendes-rodrigues, Renata Carmo-oliveira, Salvador Talavera, Montserrat Arista, Pedro L. Ortiz, Paulo Eugênio OliveiraAbstract:Apomixis and adventitious Polyembryony have been reported for several species of Bombacoideae, including Eriotheca pubescens, a tree species of the Neotropical savanna (Cerrado) areas in Brazil. However, the origin of polyembryonic seeds and their importance for the reproduction of the species remained to be shown. Here, we analyzed the early embryology of this species to establish the apomictic origin of extranumerary embryos. We also observed the geographic distribution of Polyembryony in E. pubescens, and tested if apomixis was related to the source of pollen (self or cross) and population density. Moreover, we tested if polyembryonic apomictic embryos would develop normally into seedlings. In the observed seed primordia, after a relatively long quiescent period, the zygote developed into a sexual embryo concurrently with adventitious apomictic embryos which developed from nucellus cells. Adventitious embryos develop faster than sexual ones and are morphologically similar, so that 44 days after anthesis it was virtually impossible to distinguish and trace the fate of the sexual embryo. Polyembryony is widely distributed in populations some 400 km distant, and only one strictly monoembryonic individual was observed during the study. The number of embryos per seed varied between fruits and individuals but was significantly higher in seeds from cross-pollinations than from selfs, although fruit and seed set after crosses were much lower than after selfs. Embryo development into seedlings depended on their weight at germination, but polyembryonic seeds germinated and produced up to seven seedlings per seed in greenhouse conditions. Adventitious embryony and apomictic seedlings would explain the mostly clonal populations suggested by molecular studies.
João Semir - One of the best experts on this subject based on the ideXlab platform.
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Polyploidy and Polyembryony in Anemopaegma (Bignonieae, Bignoniaceae)
Plant Reproduction, 2013Co-Authors: Fabiana Firetti-leggieri, Lúcia G. Lohmann, Suzana Alcantara, Itayguara Ribeiro Da Costa, João SemirAbstract:Polyploidy is a key process in plant evolution, with the asexual formation of embryos representing a way through which polyploids can escape sterility. The association between polyploidy and Polyembryony is known to occur in Bignoniaceae. In this study, we investigate Polyembryony in four polyploid species of Anemopaegma: A. acutifolium, A. arvense, A. glaucum and A. scabriusculum as well as in one diploid species, A. album. Polyembryony was observed only in polyploid species. We used seed dissection and germination tests to compare the number of polyembryonic seeds. We tested how the pollen source influences the number of polyembryonic seeds and the number of embryos per seed and tested the correlation between the number of viable seeds per fruit and mean number of embryos per seed. The number of polyembryonic seeds observed by seed dissection was higher than the number of polyembryonic seeds determined by the germination test, with the number of embryos produced per seed being higher than the number of seedlings. The dissection of seeds of A. glaucum indicated that a higher number of polyembryonic seeds and a higher number of embryos were present in seeds from cross-pollination than in seeds from self-pollination. On the other hand, germination tests indicated that a higher number of polyembryonic seeds were present in fruits from self-pollination than from cross-pollination. The mean number of embryos per seed was not influenced by the number of viable seeds per fruit in fruits from open pollination. These results indicate a positive relationship between Polyembryony and polyploidy in Anemopaegma.
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late acting self incompatibility and other breeding systems in tabebuia bignoniaceae
International Journal of Plant Sciences, 2005Co-Authors: Nelson Sabino Bittencourt, João SemirAbstract:Although breeding system investigations were previously performed in only nine of the 100 Tabebuia species, indications of self‐incompatibility have been found in all of them, and the four species studied for the site of incompatibility reaction showed some kind of late‐acting self‐incompatibility. Polyembryony has been found in T. chrysotricha and T. ochracea, with adventitious origin of the extra embryos being shown in the latter. We investigated the breeding system in five species of Tabebuia by hand‐pollination experiments, fluorescence microscopy study of in situ pollen tube growth, and histological analysis of postpollination events. Although both T. chrysotricha and T. heptaphylla developed fruits by self‐pollination, Polyembryony was verified only in the former, which indicates that self‐fertility in Tabebuia is not necessarily associated with apomixis. The remaining species were 100% self‐sterile. Although some penetrated ovules in crossed pistils of T. vellosoi were found at the 48‐h interval, n...
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Late‐Acting Self‐Incompatibility and Other Breeding Systems in Tabebuia (Bignoniaceae)
International Journal of Plant Sciences, 2005Co-Authors: Nelson Sabino Bittencourt, João SemirAbstract:Although breeding system investigations were previously performed in only nine of the 100 Tabebuia species, indications of self‐incompatibility have been found in all of them, and the four species studied for the site of incompatibility reaction showed some kind of late‐acting self‐incompatibility. Polyembryony has been found in T. chrysotricha and T. ochracea, with adventitious origin of the extra embryos being shown in the latter. We investigated the breeding system in five species of Tabebuia by hand‐pollination experiments, fluorescence microscopy study of in situ pollen tube growth, and histological analysis of postpollination events. Although both T. chrysotricha and T. heptaphylla developed fruits by self‐pollination, Polyembryony was verified only in the former, which indicates that self‐fertility in Tabebuia is not necessarily associated with apomixis. The remaining species were 100% self‐sterile. Although some penetrated ovules in crossed pistils of T. vellosoi were found at the 48‐h interval, n...
Tanya Scharaschkin - One of the best experts on this subject based on the ideXlab platform.
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Germination Biology and Occurrence of Polyembryony in Two Forms of Cats Claw Creeper Vine, Dolichandra unguis-cati (Bignoniaceae): Implications for Its Invasiveness and Management
Science & Engineering Faculty, 2016Co-Authors: Joshua Comrade Buru, Kunjithapatham Dhileepan, Olusegun O. Osunkoya, Tanya ScharaschkinAbstract:Cat’s claw creeper vine, Dolichandra unguis-cati (L.) Lohmann (syn. Macfadyena unguis-cati (L.) Gentry), is a major environmental weed in Australia. Two forms (“long” and “short” pod) of the weed occur in Australia. This investigation aimed to evaluate and compare germination behavior and occurrence of Polyembryony (production of multiple seedlings from a single seed) in the two forms of the weed. Seeds were germinated in growth chambers set to 10/20˚C, 15/25˚C, 20/30˚C, 30/45˚C and 25˚C, representing ambient temperature conditions of the region. Germination and Polyembryony were monitored over a period of 12 weeks. For all the treatments in this study, seeds from the short pod form exhibited significantly higher germination rates and higher occurrence of Polyembryony than those from the long pod form. Seeds from the long pod form did not germinate at the lowest temperature of 10/20˚C; in contrast, those of the short pod form germinated under this condition, albeit at a lower rate. Results from this study could explain why the short pod form of D. unguis-cati is the more widely distributed form in Australia, while the long pod form is confined to a few localities. The results have implication in predicting future ranges of both forms of the invasive D. unguis-cati, as well as inform management decisions for control of the weed. * Corresponding author.
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Germination Biology and Occurrence of Polyembryony in Two Forms of Cats Claw Creeper Vine, Dolichandra unguis-cati (Bignoniaceae): Implications for Its Invasiveness and Management
American Journal of Plant Sciences, 2016Co-Authors: Joshua Comrade Buru, Kunjithapatham Dhileepan, Olusegun O. Osunkoya, Tanya ScharaschkinAbstract:Cat’s claw creeper vine, Dolichandra unguis-cati (L.) Lohmann (syn. Macfadyena unguis-cati (L.) Gentry), is a major environmental weed in Australia. Two forms (“long” and “short” pod) of the weed occur in Australia. This investigation aimed to evaluate and compare germination behavior and occurrence of Polyembryony (production of multiple seedlings from a single seed) in the two forms of the weed. Seeds were germinated in growth chambers set to 10/20°C, 15/25°C, 20/30°C, 30/45°C and 25°C, representing ambient temperature conditions of the region. Germination and Polyembryony were monitored over a period of 12 weeks. For all the treatments in this study, seeds from the short pod form exhibited significantly higher germination rates and higher occurrence of Polyembryony than those from the long pod form. Seeds from the long pod form did not germinate at the lowest temperature of 10/20°C; in contrast, those of the short pod form germinated under this condition, albeit at a lower rate. Results from this study could explain why the short pod form of D. unguis-cati is the more widely distributed form in Australia, while the long pod form is confined to a few localities. The results have implication in predicting future ranges of both forms of the invasive D. unguis-cati, as well as inform management decisions for control of the weed.
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Germination Biology and Occurrence of Polyembryony in Two Forms of Cats Claw Creeper Vine, <i>Dolichandra unguis-cati</i> (Bignoniaceae): Implications for Its Invasiveness and Management
American Journal of Plant Sciences, 2016Co-Authors: Joshua Comrade Buru, Kunjithapatham Dhileepan, Olusegun O. Osunkoya, Tanya ScharaschkinAbstract:Cat’s claw creeper vine, Dolichandra unguis-cati (L.) Lohmann (syn. Macfadyena unguis-cati (L.) Gentry), is a major environmental weed in Australia. Two forms of the weed with distinctive leaf morphology and reproductive traits, including varying fruit size, occur in Queensland, Australia. The long pod form occurs in a few localities in Queensland, while the short pod form is widely distributed in Queensland and northern part of New South Wales. This investigation aimed to evaluate germination behavior and occurrence of Polyembryony (production of multiple seedlings from a single seed) in the two forms of the weed. Seeds were germinated in growth chambers set to 10/20°C, 15/25°C, 20/30°C, 30/45°C and 25°C, representing ambient temperature conditions of the region. Germination and Polyembryony were monitored over a period of 12 weeks. For all the treatments in this study, seeds from short pod plants exhibited significantly higher germination rates and higher occurrence of Polyembryony than those from long pod plants. Seeds from long pod plants did not germinate at the lowest temperature of 10/20°C; in contrast, those of the short pod form germinated under this condition, albeit at a lower rate (reaching a maximum 45% germination at week 12). Results from this study could explain why the short pod form of D. unguis-cati is the more widely distributed plants in Australia, while the long pod is confined to a few localities. The results have implication in predicting future range of both forms of the invasive D. unguis-cati, as well as inform management decisions for control of the weed
Jiapeng Luo - One of the best experts on this subject based on the ideXlab platform.
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The genomic features of parasitism, Polyembryony and immune evasion in the endoparasitic wasp Macrocentrus cingulum
BMC genomics, 2018Co-Authors: Chuanlin Yin, Kun Lang, Qiming Chen, Jinding Liu, Dianhao Guo, Yipei Dong, Jiapeng LuoAbstract:Parasitoid wasps are well-known natural enemies of major agricultural pests and arthropod borne diseases. The parasitoid wasp Macrocentrus cingulum (Hymenoptera: Braconidae) has been widely used to control the notorious insect pests Ostrinia furnacalis (Asian Corn Borer) and O. nubilalis (European corn borer). One striking phenomenon exhibited by M. cingulum is Polyembryony, the formation of multiple genetically identical offspring from a single zygote. Moreover, M. cingulum employs a passive parasitic strategy by preventing the host’s immune system from recognizing the embryo as a foreign body. Thus, the embryos evade the host’s immune system and are not encapsulated by host hemocytes. Unfortunately, the mechanism of both Polyembryony and immune evasion remains largely unknown. We report the genome of the parasitoid wasp M. cingulum. Comparative genomics analysis of M. cingulum and other 11 insects were conducted, finding some gene families with apparent expansion or contraction which might be linked to the parasitic behaviors or Polyembryony of M. cingulum. Moreover, we present the evidence that the microRNA miR-14b regulates the polyembryonic development of M. cingulum by targeting the c-Myc Promoter-binding Protein 1 (MBP-1), histone-lysine N-methyltransferase 2E (KMT2E) and segmentation protein Runt. In addition, Hemomucin, an O-glycosylated transmembrane protein, protects the endoparasitoid wasp larvae from being encapsulated by host hemocytes. Motif and domain analysis showed that only the hemomucin in two endoparasitoids, M. cingulum and Venturia canescens, possessing the ability of passive immune evasion has intact mucin domain and similar O-glycosylation patterns, indicating that the hemomucin is a key factor modulating the immune evasion. The microRNA miR-14b participates in the regulation of polyembryonic development, and the O-glycosylation of the mucin domain in the hemomucin confers the passive immune evasion in this wasp. These key findings provide new insights into the Polyembryony and immune evasion.
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The genomic features of parasitism, Polyembryony and immune evasion in the endoparasitic wasp Macrocentrus cingulum
BMC, 2018Co-Authors: Chuanlin Yin, Kun Lang, Qiming Chen, Jinding Liu, Dianhao Guo, Yipei Dong, Jiapeng LuoAbstract:Abstract Background Parasitoid wasps are well-known natural enemies of major agricultural pests and arthropod borne diseases. The parasitoid wasp Macrocentrus cingulum (Hymenoptera: Braconidae) has been widely used to control the notorious insect pests Ostrinia furnacalis (Asian Corn Borer) and O. nubilalis (European corn borer). One striking phenomenon exhibited by M. cingulum is Polyembryony, the formation of multiple genetically identical offspring from a single zygote. Moreover, M. cingulum employs a passive parasitic strategy by preventing the host’s immune system from recognizing the embryo as a foreign body. Thus, the embryos evade the host’s immune system and are not encapsulated by host hemocytes. Unfortunately, the mechanism of both Polyembryony and immune evasion remains largely unknown. Results We report the genome of the parasitoid wasp M. cingulum. Comparative genomics analysis of M. cingulum and other 11 insects were conducted, finding some gene families with apparent expansion or contraction which might be linked to the parasitic behaviors or Polyembryony of M. cingulum. Moreover, we present the evidence that the microRNA miR-14b regulates the polyembryonic development of M. cingulum by targeting the c-Myc Promoter-binding Protein 1 (MBP-1), histone-lysine N-methyltransferase 2E (KMT2E) and segmentation protein Runt. In addition, Hemomucin, an O-glycosylated transmembrane protein, protects the endoparasitoid wasp larvae from being encapsulated by host hemocytes. Motif and domain analysis showed that only the hemomucin in two endoparasitoids, M. cingulum and Venturia canescens, possessing the ability of passive immune evasion has intact mucin domain and similar O-glycosylation patterns, indicating that the hemomucin is a key factor modulating the immune evasion. Conclusions The microRNA miR-14b participates in the regulation of polyembryonic development, and the O-glycosylation of the mucin domain in the hemomucin confers the passive immune evasion in this wasp. These key findings provide new insights into the Polyembryony and immune evasion
Clesnan Mendes-rodrigues - One of the best experts on this subject based on the ideXlab platform.
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Polyembryony in Melastomataceae from Brazilian Cerrado: multiple embryos in a small world
Plant biology (Stuttgart Germany), 2012Co-Authors: Clesnan Mendes-rodrigues, Paulo Eugênio OliveiraAbstract:Polyembryony has been commonly associated with apomixis in the angiosperms and seems to be more common than expected, even in biomes where sexual reproduction processes are predominant. Recent studies in Cerrado, the Neotropical savannas of Central Brazil, showed high frequencies of apomixis and Polyembryony and indicated these processes as reproductive and evolutionary alternatives for plants in these areas. In this sense, we investigated the occurrence of Polyembryony and its relationships with ecological (season and type of dispersal, ploidy, species distribution and breeding system) and taxonomic (tribe) factors in the Melastomataceae, a mostly tropical family already known for its high frequency of apomixis and very common in Cerrado. We collected seeds from 69 populations of 53 species, which were sown in germination chambers. After seed germination, the presence and number of seedlings per seed were evaluated as a method to estimate Polyembryony. We encountered 18 species (33.96%) with Polyembryony (more than one seedling, or gemellar seedlings, originated per seed) concentrated in species of the tribe Miconieae (64%) and Microlicieae (16.67%), but absent in Melastomeae. Monoembryony was present only in sexual species, while all apomictic species were polyembryonic. In Miconia, the Polyembryony was correlated with polyploidy, and monoembryony with diploid species. Polyembryony was more common among species with wide distribution in the Cerrado region, which indicates that the presence of gemellar seedlings is important for establishment and survival of the group in the Cerrado biome.
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Polyembryony increases embryo and seedling mortality but also enhances seed individual survival in Handroanthus species (Bignoniaceae)
Flora - Morphology Distribution Functional Ecology of Plants, 2012Co-Authors: Clesnan Mendes-rodrigues, Marli A. Ranal, Diana Salles Sampaio, Maria Eugênia Costa, Ana Paula Souza Caetano, Nelson Sabino Bittencourt Júnior, Paulo Eugênio OliveiraAbstract:a b s t r a c t Polyembryony seems to be advantageous to mother plants in detriment of their siblings which face com- petition since the beginning of seed development. This competition may limit the turnover of embryos into seedlings and their survival ability. We analysed Polyembryony frequency and embryo to seedling turnover in three Handroanthus species with sporophytic apomixis. We tested if the embryo number per seed affected seed and embryo morphometry, seedling survival ability and seed individual survival (i.e. survival of at least one seedling per seed). The number of embryos per seed was compared with seedling number at different developmental stages. All 14 populations showed high frequencies of polyembry- onic seeds (21-91%). As the number of embryos per seed increased (up to eight embryos/seed), there was a reduction of mean embryo mass, area, seedling length, individual seedling survival ability, and embryo to seedling turnover. There was also an increase in embryo morphological anomalies. However, enhanced seed individual survival was also observed. Thus, the high frequency of polyembryonic seeds and the increase in seed individual survival support the idea that Polyembryony represents an alternative reproductive mechanism which can favours these species.
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Does Polyembryony reduce seed germination and seedling development in Eriotheca pubescens (Malvaceae: Bombacoideae)?
American journal of botany, 2011Co-Authors: Clesnan Mendes-rodrigues, Marli A. Ranal, Paulo Eugênio OliveiraAbstract: Premise of the Study: Competition between siblings affect their growth and survival ability. An extreme situation is Polyembryony, whereby siblings are exposed to competition from the beginning of their development. But its effect on plant reproduction is seldom tested. Eriotheca pubescens is a tree in the Cerrado, the Neotropical Savannas in Brazil, with apomictic/ polyembryonic and sexual/monoembryonic populations. We tested the effect of Polyembryony on germination, emergence, and growth in E. pubescens . This may have ecological consequences within the Cerrado, where seedling establishment is critical for species persistency and distribution. Methods: We tested the effect of embryonic origin on germinability- and time-related parameters using seeds from different populations. We measured cultivated seedling growth continuously for 70 d and exhumed them after 9 mo to measure seedling biometry traits such as shoot, root, and seedling mass. We compared these traits with the number of seedlings emerged per seed and fi tted data to a linear regression model. Key Results: Polyembryony reduced germinability and seedlings ’ initial growth in E. pubescens . Seedling traits and biomass decreased with the number of seedlings arising per seed. But the effect of Polyembryony was mostly on initial seedling size and not on seedling growth rate. Conclusions: Polyembryony and apomixis affected germination and led to smaller seedlings compared with monoembryonic sexual counterparts. Although smaller, these extra seedlings may enhance per-seed survival chances in the Cerrado conditions of seasonal drought and frequent fi res and explain the predominance of polyembryonic populations.
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Polyembryony and apomixis in Eriotheca pubescens (Malvaceae - Bombacoideae).
Plant biology (Stuttgart Germany), 2005Co-Authors: Clesnan Mendes-rodrigues, Renata Carmo-oliveira, Salvador Talavera, Montserrat Arista, Pedro L. Ortiz, Paulo Eugênio OliveiraAbstract:Apomixis and adventitious Polyembryony have been reported for several species of Bombacoideae, including Eriotheca pubescens, a tree species of the Neotropical savanna (Cerrado) areas in Brazil. However, the origin of polyembryonic seeds and their importance for the reproduction of the species remained to be shown. Here, we analyzed the early embryology of this species to establish the apomictic origin of extranumerary embryos. We also observed the geographic distribution of Polyembryony in E. pubescens, and tested if apomixis was related to the source of pollen (self or cross) and population density. Moreover, we tested if polyembryonic apomictic embryos would develop normally into seedlings. In the observed seed primordia, after a relatively long quiescent period, the zygote developed into a sexual embryo concurrently with adventitious apomictic embryos which developed from nucellus cells. Adventitious embryos develop faster than sexual ones and are morphologically similar, so that 44 days after anthesis it was virtually impossible to distinguish and trace the fate of the sexual embryo. Polyembryony is widely distributed in populations some 400 km distant, and only one strictly monoembryonic individual was observed during the study. The number of embryos per seed varied between fruits and individuals but was significantly higher in seeds from cross-pollinations than from selfs, although fruit and seed set after crosses were much lower than after selfs. Embryo development into seedlings depended on their weight at germination, but polyembryonic seeds germinated and produced up to seven seedlings per seed in greenhouse conditions. Adventitious embryony and apomictic seedlings would explain the mostly clonal populations suggested by molecular studies.