-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.

RESUMEN -Las estadísticas oficiales informaron que en 2008 se cultivaron 264 944 ha con valor de la producción de $ 14 741 millones de pesos, en 20 frutales de clima templado; mientras que, en 35 tropicales y subtropicales fue de 1 822748 ha con valor de $ 43 463 millones de pesos. De los 55 frutales, sólo naranjo (Citrus sinensis), mango (Mangifera indica), Aguacate (Persea americana), limón mexicano (C. aurantifolia), banano (Musa acuminata), lima persa (C. latifolia) y manzano (Malus domestica) se cultivan más de 50 000 ha, lo que explica porque es limitada la oferta de frutas en las grandes ciudades (Distrito Federal, Monterrey, Guadalajara, Puebla, Veracruz, entre otras). Considerando que el 79,27% de la superficie plantada con frutales tropicales y subtropicales es de temporal, las densidades de plantación son bajas, la propagación de plantas no se hace en viveros certificados (sólo cítricos), los rendimientos son bajos en comparación con otros países productores. Por otra parte, debido a la falta de técnicos capacitados, en los últimos 28 años la demanda de fruta se ha solucionado incrementando la superficie plantada, pero los rendimientos han disminuido. La presencia de nuevas enfermedades; Huanglongbing, Meleira, Sunblotch, plantean nuevos retos y también posibilidades si utilizamos los avances tecnológicos. La fruticultura es una alternativa viable pero deben utilizar altas densidades, árboles de porte bajo, plantas de origen genético conocido y calidad fitosanitaria probada que permitan tener mayores rendimientos y con ello competitividad. Terminós para indexación: Fruticultura, Producción, mango, cítricos, aguacate, papaya. ADVANCES IN MÉXICO FRUITCULTUREABSTRACT -Official statistics in 2008 indicate that 20 species of temperate climate fruit trees were cultivated in 264 944 ha and the production value was $ 14 741 million pesos; while 35 species of tropical and subtropical fruits were cultivated in 1 822 748 ha and the production value was $ 43 463 million pesos. Of the 55 fruit trees, only orange (Citrus sinensis), mango (Mangifera indica), avocado (Persea americana), Mexican lime (C. aurantifolia), banana (Musa acuminata), Persian lime (C. latifolia), and apple tree (Malus domestica) were cultivated in more than 50 000 ha, it explains why the supply of fruits in large cities (Mexico City, Monterrey, Guadalajara, Puebla, Veracruz, among others) is limited. Thinking about that 79,27% of the tropical and subtropical fruit planted area is rain fed; plant propagation is not grown in certified nurseries (only citrus trees), the plantation densities and yields are lower than others producing countries. Moreover, due to the lack of specialists, in the last 28 years the fruit demand has been solved by increasing the planted area, but yields have decreased. The new diseases; huanglongbing, Papaya meleira, Sunblotch, create the necessity of challenges and opportunities, if we use technological advances. If we use high density, dwarf trees, plants of known genetic origin and phytosanitary quality, which allow...

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Dieback of sapote mamey [Pouteria sapota (Jacq.) H. E. Moore and Stearn] grafts caused by Lasiodiplodia theobromae significantly reduces the success of grafting in Mexican nurseries. Semi-commercial tests were conducted in a sapote mamey nursery during two grafting seasons to evaluate the effectiveness of a physical treatment (washing) and three chemical treatments (fungicide dip) on scions. Washing reduced disease incidence up to 31 %, whereas chemical treatment reduced it up to 62 %. The combination of washing and thiabendazole dip resulted in an incidence decrease of 81 %. Twelve other fungicides were screened in vitro to evaluate mycelial growth inhibition of L. theobromae. The pre-formulated mix of cyprodinil + fludioxinil was the most effective fungicide with EC50 value of 0.0043 μg mL-1, followed by pyraclostrobin + boscalid, prochloraz and tebuconazole with EC50 values < 0.1 μg mL-1, and iprodione and thiabendazole with EC50 values < 1.0 μg mL-1. This study provides novel information about strategies for controlling L. theobromae infection during the grafting process of sapote mamey and it also showed the effectiveness of several fungicides under in vitro conditions for controlling this plant pathogenic fungus.

Vegetative propagation of Sprekelia (Sprekelia formosissima Herbert.) in natural conditions is limited because it produces only one bulb per year or none. The objective of this research was to generate an in vitro propagation protocol for this species to increase its commercial propagation rate without extracting the species from its natural habitat. Bulbs of 4 to 5 cm in diameter were used as disinfested donor explant material; 1 cm2 explants were obtained from the cataphyll leaves with and without a portion of basal disc; these explants were established in MS medium supplemented with 8.87 μM of N6 benzyl adenine (BA) and 0.98 μM of indole-3- butyric acid (IBA). For shoot multiplication, bulblets obtained from the previous phase were used as explants and cultivated in MS medium with 2.5, 5, 10, 15 and 20 μM of BA combined with IBA at a 10:1 ratio (BA: IBA). Shoots obtained from multiplication were established in MS medium supplemented with 1, 2, 3, 4, and 5 % (w/v) sucrose to promote growth. Bulblets were rooted in MS medium supplemented with 0, 0.49, 0.98, 1.96, 3.93 and 7.8 μM of IBA. Once roots formed, they were transferred to soil to assess their acclimation. We obtained 89.1 % of aseptic explants, of which 86 % formed two shoots on the average. Multiplication of shoots increased as BA concentration increased in culture medium, and the best results (75 % of bulblets with shoots, 2.66 shoots per bulblet and 2.0 mm diameter shoots) were obtained with 20 μM BA. The best bulb growth in diameter (4.2 mm) and number of bulblet leaves (3.5) was obtained with 5 % sucrose. The use of 0.98 μM IBA resulted in greater rooting percentage (93.7) and number of roots per bulblet (2.0), which were 2.4 cm long on average. Up to 83 % of the bulblets survived acclimation. This protocol to micropropagate Sprekelia formosissima allowed the production of at least 96 bulblets from one mother bulb in a six months period of in vitro culture.