Efecto de 6-BAP y AIA en el establecimiento in vitro de meristemos de Colocasia esculenta (L.) Schott cv. ‘INIVIT MC 2012’

The use of meristems for the in vitro establishment of Colocasia esculenta (L.) Schott cv. 'INIVIT MC-2012' decreases bacterial contamination but is required to increase its growth. The objective of this work was to determine the effect of 6-Benzylaminopurine and indoleacetic acid on its in vitro establishment. Various concentrations of the two growth regulators were included in the culture medium and with the best combination the explants were cultured in shaking and static liquid culture medium. With the use of the culture medium constituted by 80% of the salts and vitamins MS, 30 g l-1 sucrose, 0.1 g l-1 myo-inositol, 0.1 mg l-1 6-BAP, 0.05 mg l-1 of AIA and culture in agitation were obtained meristems with the appropriate morphological characteristics to transfer to the multiplication phase at 28 days of culture.Keywords: orbital agitator, propagation, taroEl empleo de meristemos para el establecimiento in vitro de Colocasia esculenta (L.) Schott cv.  ‘INIVIT MC-2012’ disminuye la contaminación bacteriana pero se requiere incrementar su crecimiento. El objetivo de este trabajo fue determinar el efecto de 6-Bencilaminopurina y ácido indolacético en su establecimiento in vitro. Se incluyeron varias concentraciones de los dos reguladores del crecimiento en el medio de cultivo y con la mejor combinación se cultivaron los explantes en medio de cultivo líquido en agitación y estático. Con el empleo el medio de cultivo constituido por el 80% de las sales y vitaminas MS, 30 g l-1 de sacarosa, 0.1 g l-1 de mio-inositol, 0.1 mg l-1 de 6-BAP, 0.05 mg l-1 de AIA y cultivo en agitación se lograron meristemos con las características morfológicas adecuadas para pasar a la fase de multiplicación a los 28 días de cultivo. Palabras clave: agitador orbital, malanga, propagació

First report of Cladosporium colocasiae causing leaf spot on taro (Colocasia esculenta) in Mexico

In September 2017, symptoms of leaf spot were observed on approx. 80% of taro (Colocasia esculenta var. antiquorum) plants at a commercial field located in San Juan Bautista Tuxtepec, Oaxaca, Mexico. Lesions on diseased leaves were dark brown and oval to irregular, sometimes coalesced to cover large areas of the leaf surface. To isolate the fungus, small fragments from adjacent tissue to lesions of symptomatic leaves were excised and surface disinfested by immersion in a 1% NaOCl for 2 min, rinsed three times in sterile distilled water, dried in blotter paper, and placed in Petri plates containing potato dextrose agar (PDA) amended with ampicillin (20 mg/l) and rifampicin (20 mg/l). The plates were incubated at 25ºC under constant white light for 8 days and then mycelial plugs were aseptically transferred to fresh PDA medium. Pure cultures were obtained by monoconidial isolation technique. Colonies on PDA exhibited aerial mycelium sparse, grey-olivaceous to darkolivaceous, and with sporulation profuse. Conidiophores were solitary, erect, straight or slightly flexuous, cylindrical-oblong, olivaceous-brown, nodulose, usually unbranched, and measuring up to 650 μm long. Conidia catenate in branched chains, ellipsoidal to cylindrical, smooth, aseptate or 1?2-septate, olivaceous-brown, 9 to 18 × 5 to 8 μm. Based on morphological characteristics, the fungus was identified as Cladosporium colocasiae (Bensch et al. 2012; García and Moya 2015). A representative isolate was deposited in the Culture Collection of Phytopathogenic Fungi at the Chapingo Autonomous University as UACH 291. For molecular identification, the internal transcribed spacer (ITS) region, and part of the translation elongation factor 1-α (EF1-α) gene were amplified by PCR, and sequenced using the primer sets ITS5/ITS4 (White et al. 1990) and EF1-728F/EF1-986R (Carbone and Kohn 1999), respectively. The sequences were deposited in GenBank (Accession numbers ITS:MH191366 and EF1-α:MH191367). A phylogenetic analysis using Bayesian inference and including published ITS and EF1-α sequence dataset for C. colocasiae and other Cladosporium species was performed. The phylogenetic analysis resulted in a well-supported clade grouped with the type species of C. colocasiae. The pathogenicity of the fungus was verified on taro plants growing in a greenhouse. Two leaves from each of five 5-month-old taro plants were sprayed with a conidial suspension (104 spores/ml). Five leaves were mock inoculated with distilled water as a control. All plants were covered for 48 h with a plastic bag to keep moisture and then were maintained in a greenhouse at temperatures ranging from 25 to 32°C for 15 days. The pathogenicity test was performed twice. Symptoms of leaf spots were observed after 10 days on all leaves inoculated with conidial suspensions, while control leaves remained symptomless. Koch´s postulates were fulfilled when the pathogen was reisolated 100% from the diseased leaves. Cladosporium colocasiae has been reported on Colocasia spp. in North America (USA), Caribbean islands, South America, Europe, as well as widely distributed in Africa, Asia, and Australasia (Bensch et al. 2012; Farr and Rossman 2018). To our knowledge, this is the first report of C. colocasiae causing leaf spot on taro in Mexico. The occurrence of this pathogen presents a threat to the production of taro in this area of southeastern Mexico, and therefore, effective management strategies should be implemented.Fil: Vásquez-López, Alfonso. Instituto Politécnico Nacional; MéxicoFil: Palacios-Torres, Rogelio Enrique. Universidad del Papaloapa; MéxicoFil: Montiel-Frausto, Laura Belem. Instituto Politécnico Nacional; MéxicoFil: Medero Vega, Víctor Reinaldo. Instituto de Investigaciones de Viandas Tropicales; CubaFil: Bernardi Lima, Nelson. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Instituto de Patología Vegetal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Camacho-Tapia, Moises. Universidad Autonoma Chapingo; MéxicoFil: Tovar-Pedraza, Juan Manuel. Centro de Investigación En Alimentación y Desarrollo; Méxic

Somatic embryogenesis in plantain cultivar 'FHIA - 25' (AAB) from meristem tips

Plantain cultivar 'FHIA – 25' (AAB) shows high yielding qualities and high resistance to Black Sigatoka disease, but its sugar content in the fruit is low, so a regeneration method at cell level is necessary, such as somatic embryogenesis supported by biotechnological tools to improve fruit quality. This work was performed with the aim of establishing a plant regeneration method via somatic embryogenesis using initial explants of shoot apices from axillary buds in liquid culture medium. Homogenous embryogenic cell suspensions were obtained from mentioned explants. The highest cellular multiplication rates were achieved at 3,0% density. The incubation of somatic embryos during 30 days in the maturation culture medium permitted to increase germination. During the acclimatization stage, plants regenerated from somatic embryos, as well as plants from organogenesis, showed a high survival percentage (98 and 97 respectively), without somaclonal variation

Embriogénesis somática en el cultivar de plátano ‘FHIA – 25’ (AAB) a partir de ápices meristemáticos

El cultivar de plátano ‘FHIA – 25’ (AAB), posee excelente rendimiento y alta resistencia a “Sigatoka negra”, pero con la limitante del bajo contenido de azúcar en su fruto, lo cual hace que sea necesario disponer de un método de regeneración de plantas a nivel celular como la embriogénesis somática, que se complemente a técnicas biotecnológicas de  transformación genética para mejorar la calidad del fruto.  El presente trabajo se realizó con el objetivo de establecer una metodología de regeneración vía embriogénesis somática a partir del explante inicial ápices de brotes axilares establecidos directamente en medio de cultivo líquido. Se obtuvieron suspensiones celulares embriogénicas homogéneas a partir del explante antes mencionado. Se lograron las mayores tasas de multiplicación  a la densidad celular  de 3,0%. La incubación de los embriones somáticos durante 30 días en el medio de cultivo de maduración permitió incrementar la germinación de los mismos. Durante la fase de aclimatización las plantas provenientes de los embriones somáticos, así como las plantas regeneradas por organogénesis, mostraron un alto porcentaje de supervivencia (98 y 97 %, respectivamente), sin la presencia de variación somaclonal.Plantain cultivar 'FHIA – 25' (AAB) shows high yielding qualities and high resistance to Black Sigatoka disease, but its sugar content in the fruit is low, so a regeneration method at cell level is necessary, such as somatic embryogenesis supported by biotechnological tools to improve fruit quality. This work was performed with the aim of establishing a plant regeneration method via somatic embryogenesis using initial explants of shoot apices from axillary buds in liquid culture medium. Homogenous embryogenic cell suspensions were obtained from mentioned explants. The highest cellular multiplication rates were achieved at 3,0% density. The incubation of somatic embryos during 30 days in the maturation culture medium permitted to increase germination. During the acclimatization stage, plants regenerated from somatic embryos, as well as plants from organogenesis, showed a high survival percentage (98 and 97 respectively), without somaclonal variation.Key words: somatic embryo, Musa, cell suspensions

Multiplicación in vitro del clon de malanga ‘Viequera’ (Xanthosoma spp.) en sistemas de cultivo semiautomatizado

In Cuba, theXanthosoma genus is highly demanded in the preference of the population in relation to other edible aroids. The temporary immersion system (TIS) may constitute a micropropagation alternative to obtain high quality seed in this crop. The effect of two Semi-automated Culture Systems (SIT) and Constant Immersion Systems (CIS) with aeration through continuous bubbling in culture medium during the multiplication stage of axillaries shoot buds was evaluated. Results allowed demonstrating superiority in the efficiency of SIT regarding CIS in the sprout multiplication of clone ‘Viequera’. Axillaries sprout buds cultivated in TIS showed the best results in the multiplication compared with CIS and the static culture system with passive renewal of the internal atmosphere was used as control. The culture conditions created in the temporary immersion system forin vitro multiplication of axillaries sprout buds achievedthe highest multiplication coefficient(9.56). Thisin vitro culture system will allow increasing the multiplication coefficients in the micropropagation for seed productionin this genus.Keyword: multiplication coefficient, micropropagation, temporary immersion systemEn Cuba, el género de malanga Xanthosoma es el de mayor demanda en la preferencia de la población con relación a otras aráceas comestibles. El cultivo en inmersión temporal (SIT) puede constituir una alternativa de micropropagación, para obtener semilla de alta calidad en este cultivo. Se determinó el efecto de dos sistemas de cultivo: semi-automatizados SIT y Sistema de Inmersión Constante con aireación mediante burbujeo continuo en el medio de cultivo (SIC) en la fase de multiplicación de los brotes de yemas axilares. Los resultados permitieron demostrar la superioridad en la eficiencia del SIT respecto al SIC en la multiplicación de los brotes del clon ‘Viequera’. Los brotes de yemas axilares cultivados en este sistema de cultivo mostraron los mejores resultados en la multiplicación respecto al SIC y el sistema de cultivo estático con renovación pasiva de la atmósfera interna, utilizado como control. Con las condiciones de cultivo creadas en el sistema de inmersión temporal para la multiplicación in vitro de los brotes de yema axilaraes se lograron los más altos coeficientes de multiplicación (9.56). El uso de este sistema de cultivo in vitro, posibilitará incrementar los coeficientes de multiplicación en la micropropagación para la producción de semilla en este género.Palabra clave: coeficiente de multiplicación, micropropagación, Sistema de inmersión tempora