-The objectives of this work were to evaluate the frequency of polyembryony, and to identify zygotic and nucellar seedlings of Citrus volkameriana using RAPD. Twenty-five polyembryonic and eight monoembryonic seeds were cultivated in vitro for six months. DNA from seedlings was extracted and used in combination with five RAPD primers to identify zygotic or nucellar origin of the seedlings. Environmental conditions of the year affected significantly (P≤0.05) the morphological characteristics of fruits and the number of embryos per seed. Polyembryonic seeds ranged from 30.9%, 44.8% to 54.4% over three years. Morphological characteristic was not correlated with polyembryony. In vitro culture enable all embryos of each seed to grow, favoring the percentage of seedlings identified as zygotic. In polyembryonic and monoembryonic seeds, 25.9% and 87.5% of the seedlings, respectively, were sexually originated. In polyembryonic seeds, not all zygotic seedlings were produced by small embryos located at the micropyle.Index terms: Citrus volkameriana, rootstock, embryo culture, molecular markers, polymorphism. Termos para indexação: Citrus volkameriana, porta-enxerto, cultura de embriões, marcadores moleculares, polimorfismo.
Poliembrionia e identificação de seedlings zigóticos e nucelares de limão volkameriano com RAPD
Echeveria, género representativo de Crassulaceae por representar 97% de especies endémicas; sus plantas tienen características morfológicas atractivas para la horticultura ornamental. El conocimiento de las características reproductivas es útil para el mejoramiento genético, necesario para ser utilizado en las polinizaciones y aumentar la posibilidad de éxito de la fecundación. El objetivo fue conocer la viabilidad de polen, receptividad del estigma y tipo de polinización de cinco especies de Echeveria, con fines de mejoramiento genético. El trabajo se realizó de 2011 a 2013, en Cuernavaca, Morelos. Se usaron cinco especies E. agavoides, E. elegans, E. runyonii, E. pumila, E. perle. La viabilidad de polen se determinó mediante el método de tinción con ácido ácetico-carmín. La receptividad del estigma se evaluó con el método de Osborn; la evaluación fue a las 8:00, 10:00, 12:00, 14:00, 16:00, y 18:00 h. Para tipo de polinización se realizaron cuatro modalidades: 1) autopolinización; 2) emascular y cubrir flores; 3) polinización cruzada intra específica; y 4) polinización cruzada inter específica; se evaluo amarre de fruto y viabilidad de semillas. E. agavoides tuvo mayor porcentaje de polen viable (72.7%). La mayor receptividad se tuvo de 12:00 a 14:00 h (94.6 a 98%). En las cuatro modalidades de polinización se obtuvó 100% de amarre de fruto; solo hubo semilla viable en los frutos de polinización cruzada intra-específica (12.3%) y polinización cruzada inter-específica (11.3 a 12.3%). La polinización de las especies estudiadas fue cruzada. E. perle y E. runyonii no pueden fungir como hembras por no formar semillas viables.
-The objective of this work was to evaluate the occurrence of polyembryony in the mango cultivars Manila and Ataulfo, and to determine whether seedlings cultured in vitro are zygotic or nucelar. Percentage of polyembryony was calculated and the number of embryos in 100 seeds of each cultivar was recorded. 'Manila' exhibited 97% polyembryony with 3.4 embryos per seed, while 'Ataulfo' had 95% polyembryony with 3.2 embryos per seed. Later, 20 seeds of each cultivar were established in vitro, and it was analyzed those in which all embryos germinated (12 seeds from 'Manila' and 7 from 'Ataulfo'). DNA was extracted from seedling leaf tissue, and its origin was identified with 14 RAPD primers. The polymorphic markers recognized the seedlings of sexual origin in seven of nine 'Manila' polyembryonic seeds, and in four of seven 'Ataulfo' ones. Also, in polyembryonic seeds not all zygotic seedlings were produced by small embryos located at the micropyle.Index terms: Mangifera indica, embryo culture, funiculus, molecular markers, polymorphism.
Identificação de plântulas zigóticas e nucelares em cultivares de manga poliembriônicasResumo -O objetivo deste trabalho foi avaliar a ocorrência de poliembrionia nas mangas 'Manila' e 'Ataulfo' e determinar se as plântulas cultivadas in vitro são zigóticas ou nucelares. A percentagem de poliembrionia foi calculada e o número de embriões em 100 sementes de cada cultivar foi determinado. 'Manila' apresentou 97% de poliembrionia com 3,4 embriões por semente, enquanto 'Ataulfo' teve 95% de poliembrionia com 3,2 embriões por semente. Posteriormente, 20 sementes de cada cultivar foram cultivadas in vitro, tendose analisado aquelas em que todos os embriões germinaram (12 sementes de 'Manila' e sete de 'Ataulfo'). O DNA foi extraído a partir de tecidos foliares das plântulas, e sua origem foi identificada com 14 iniciadores RAPD. Os marcadores polimórficos reconheceram o embrião de origem sexual em sete das nove sementes poliembriônicas de 'Manila' e em quatro das sete sementes de 'Ataulfo'. Além disso, nem todas as plântulas zigóticas foram produzidas por embriões pequenos localizados no micrófilo das sementes poliembriônicas.Termos para indexação: Mangifera indica, cultura de embriões, funículo, marcadores moleculares, polimorfismo.
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