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Oeceoclades maculata is a terrestrial orchid species that has potential for commercial purposes. Taking that into consideration, the present investigation aimed at studying its germination and initial development in vitro as well as its acclimatization. The influence of Murashige and Skoog (MS), Knudson C (KC), and Vacin and Went (VW) media in the presence and absence of 0.3% activated charcoal on in vitro germination and protocorm development were investigated. The effects of different concentrations of BA in combination with 0.5 mg L-1 NAA on seedling multiplication and growth were evaluated. The possibility of using dark-grown stem segments for micropropagation and acclimatization under laboratory and field conditions was also assessed. The results indicated that the most adequate media for germination were full-strength MS enriched with activated charcoal or KC supplemented with 1.5 mg L-1 BA in combination with 0.5 mg L-1 NAA. In terms of protocorm development, KC supplemented with 1.5 mg L-1 BA alone or in combination with 0.5 mg L-1 NAA provided the best results. The addition of 1.5 mg L-1 BA in combination with 0.5 mg L-1 NAA to KC medium favored the best results for seedling multiplication and development. The use of dark-grown stem segments is a viable alternative for the micropropagation of O. maculata. Regarding acclimatization, 100% survival of plants was observed during the initial phases and under field conditions average survival was 53.33%.(AU)

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Tissue culture techniques have been employed for orchid mass propagation by means of themorphogenetic route of protocorm like-bodies (PLBs). This study aimed to analyze and compare Indoleaceticacid (IAA) and sugar endogenous levels in protocorm-like bodies (PLBs) induction and developmentin Cattleya tigrina, in order to better understand this process and to optimize micropropagation procedureprotocols. Leaves grown on MS (Murashige and Skoog) culture medium, suplemented with 9 μM TDZfor PLBs induction and development were collected after 0, 2, 7, 14, 30, 60 and 100 days of cultivation, forfurther analysis. Increase of IAA and reduction of sugar levels are strongly related to morphogeneticresponse, that is, PLBs formation over the preexisting ones and leaf primordia formation. Sucrose, fructoseand glucose presence in this study is related to cell signaling. Thus, hormonal signals and carbohydratesalter metabolism, triggering PLBs initiation and development in C. tigrina.

Técnicas de cultura de tecidos têm sido empregadas para a propagação em massa de orquídeaspor meio da via morfogenética de estruturas semelhantes a protocormos (ESPs). O estudo teve comoobjetivo analisar e comparar os níveis endógenos de ácido indol-3-acético (AIA) e de açúcares na indução eno desenvolvimento de estruturas semelhantes a protocormos (ESPs) em Cattleya tigrina, visando à melhorcompreensão deste processo e à otimização de protocolos de micropropagação. Folhas cultivadas em meiode cultura MS (Murashige & Skoog), suplementadas com 9 μM de TDZ para indução e desenvolvimentode ESPs foram coletadas após 0, 2, 7, 14, 30, 60 e 100 dias de cultivo, para posterior análise. O aumento dosníveis de AIA e a redução dos níveis de açúcar estão fortemente relacionados à resposta morfogenética, ouseja, à formação de ESPs sobre os pré-existentes e à formação de primórdios foliares. A presença desacarose, frutose e glicose neste estudo está relacionada à sinalização celular. Assim, sinais hormonais ecarboidratos alteram o metabolismo, desencadeando a iniciação e o desenvolvimento de ESPs em C. tigrina.

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RESUMEN

Tissue culture techniques have been employed for orchid mass propagation by means of themorphogenetic route of protocorm like-bodies (PLBs). This study aimed to analyze and compare Indoleaceticacid (IAA) and sugar endogenous levels in protocorm-like bodies (PLBs) induction and developmentin Cattleya tigrina, in order to better understand this process and to optimize micropropagation procedureprotocols. Leaves grown on MS (Murashige and Skoog) culture medium, suplemented with 9 μM TDZfor PLBs induction and development were collected after 0, 2, 7, 14, 30, 60 and 100 days of cultivation, forfurther analysis. Increase of IAA and reduction of sugar levels are strongly related to morphogeneticresponse, that is, PLBs formation over the preexisting ones and leaf primordia formation. Sucrose, fructoseand glucose presence in this study is related to cell signaling. Thus, hormonal signals and carbohydratesalter metabolism, triggering PLBs initiation and development in C. tigrina.(AU)

Técnicas de cultura de tecidos têm sido empregadas para a propagação em massa de orquídeaspor meio da via morfogenética de estruturas semelhantes a protocormos (ESPs). O estudo teve comoobjetivo analisar e comparar os níveis endógenos de ácido indol-3-acético (AIA) e de açúcares na indução eno desenvolvimento de estruturas semelhantes a protocormos (ESPs) em Cattleya tigrina, visando à melhorcompreensão deste processo e à otimização de protocolos de micropropagação. Folhas cultivadas em meiode cultura MS (Murashige & Skoog), suplementadas com 9 μM de TDZ para indução e desenvolvimentode ESPs foram coletadas após 0, 2, 7, 14, 30, 60 e 100 dias de cultivo, para posterior análise. O aumento dosníveis de AIA e a redução dos níveis de açúcar estão fortemente relacionados à resposta morfogenética, ouseja, à formação de ESPs sobre os pré-existentes e à formação de primórdios foliares. A presença desacarose, frutose e glicose neste estudo está relacionada à sinalização celular. Assim, sinais hormonais ecarboidratos alteram o metabolismo, desencadeando a iniciação e o desenvolvimento de ESPs em C. tigrina.(AU)

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PREMISE OF THE STUDY: The investigation of reproductive barriers between sister species can provide insights into how new lineages arise, and how species integrity is maintained in the face of interspecific gene flow. Different pre- and postzygotic barriers can limit interspecific gene exchange in sympatric populations, and different sources of evidence are often required to investigate the role of multiple reproductive isolation (RI) mechanisms. METHODS: We tested the hypothesis of hybridization and potential introgression between Epidendrum secundum and Epidendrum xanthinum, two Neotropical food-deceptive orchid species, using nuclear and plastid microsatellites, experimental crosses, pollen tube growth observations, and genome size estimates. KEY RESULTS: A large number of hybrids between E. secundum and E. xanthinum were detected, suggesting weak premating barriers. The low fertility of hybrid plants and the absence of haplotype sharing between parental species indicated strong postmating barriers, reducing interspecific gene exchange and the development of advanced generation hybrids. Despite the strength of reproductive barriers, fertile seeds were produced in some backcrossing experiments, and the existence of interspecific gene exchange could not be excluded. CONCLUSIONS: Strong but permeable barriers were found between E. secundum and E. xanthinum. Indeed, haplotype sharing was not detected between parental species, suggesting that introgression is limited by a combination of genic incompatibilities, including negative cytonuclear interactions. Most taxonomic uncertainties in this group were potentially influenced by incomplete RI barriers between species, which mainly occurred sympatrically.

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