Cacti species are plants that are well adapted to growing in arid and semiarid regions where the main problem is water availability. Cacti have developed a series of adaptations to cope with water scarcity, such as reduced leaf surface via morphological modifications including spines, cereous cuticles, extended root systems and stem tissue modifications to increase water storage, and crassulacean acid metabolism to reduce transpiration and water loss. Furthermore, seeds of these plants very often exhibit dormancy, a phenomenon that helps to prevent germination when the availability of water is reduced. In general, cactus species exhibit a low growth rate that makes their rapid propagation difficult. Cacti are much appreciated as ornamental plants due to their great variety and diversity of forms and their beautiful short-life flowers; however, due to difficulties in propagating them rapidly to meet market demand, they are very often over-collected in their natural habitats, which leads to numerous species being threatened, endangered or becoming extinct. Therefore, plant tissue culture techniques may facilitate their propagation over a shorter time period than conventional techniques used for commercial purposes; or may help to recover populations of endangered or threatened species for their re-introduction in the wild; or may also be of value to the preservation and conservation of the genetic resources of this important family. Herein we present the state-of-the-art of tissue culture techniques used for ornamental cacti and selected suggestions for solving a number of the problems faced by members of the Cactaceae family.

The production of garlic (Allium sativum) in Mexico has become reduced due the infections caused by viruses. The present study is aimed to identify potyvirus, onion yellow dwarf virus (OYDV), and leek yellow striped virus (LYSV), carlavirus, shallot latent virus (SLV), garlic common latent virus (GarCLV), and tospovirus, iris yellow spot virus (IYSV) by means of ELISA, in the state of Guanajuato, Mexico during the autumn-winter cycle 2008-2009. The five viruses were present in the ICA, SAL and SLP; LYSV tests, with 100,100 and 100% incidence, OYDV with 92, 94 and 91%, GarCLV with 89, 92 y 92%, SLV with 28, 100 and 61%, IYSV with 42, 36 and 42%, for the first, second and third sampling dates, respectively. Despite the viral infections, a total of 12 compounds of the Taiwan garlic variety were evaluated, out of which, 5 (Santa Teresa, Table 3, Salamanca, Gto.) and 4 (El Pato, Warehouses, Salamanca, Gto.) produced the highest yield (13.6 ton/ha), of the bulb.

La producción de ajo (Allium sativum) en México se ha reducido debido a infecciones causadas por virus. En el presente trabajo realizado en el estado de Guanajuato, México, durante el ciclo otoño-invierno 2008-2009, se identificaron mediante ELISA, los potyvirus, virus enanismo amarillo de la cebolla (Onion yellow dwarf virus: OYDV) y virus rayado amarillo del puerro (Leek yellow stripe virus: LYSV), los carlavirus, virus latente del shallot (Shallot latent virus: SLV), virus latente común del ajo (Garlic common latent virus: GarCLV), y el tospovirus, virus manchado amarillo del iris (Iris Yellow Spot Virus: IYSV). Los cinco virus estuvieron presentes en los ensayos ICA, SAL y SLP; LYSV con 100,100 y 100% de incidencia, OYDV con 92,94 y 91%, GarCLV con 89, 92 y 92%, SLV con 28, 100 y 61%, IYSV con 42, 36 y 42%, para la primer, segunda y tercer fechas de muestreo, respectivamente. Se evaluaron 12 compuestos de ajo de la variedad Taiwán de los cuales el 5 (Santa Teresa, Tabla 3, Salamanca, Gto.) y el 4 (El Pato, Bodegas, Salamanca, Gto.) produjeron los mayores rendimientos (13.6 ton/ha) de bulbo, a pesar de las infecciones virales.

The Agave genus belongs to the Agavaceae family and contains around 200 species with diverse uses. Agave tequilana is one of the most important species at the industrial level in México since sugars accumulated in the stems of these plants are used to produce the spirit called tequila. Agave production is supported by intensive clonal propagation and the suppression of the sexual reproduction, leading to reduction in genetic variability and a greater susceptibility to plagues and diseases in commercial plantations. Nevertheless, this study with plants from a field in Guanajuato, México, carried out using AFLP markers shows that differences at the molecular level exist between offsets and bulbils produced asexually from the same mother plant (75.08 and 86.06 % polymorphic loci, respectively). Although a significant level of polymorphism is observed between rhizome offsets, levels are even higher between bulbils, reaching levels comparable to those found between plantlets produced from seeds (90.1 %). We propose a more detailed study of the factors causing genetic variability between asexually propagated individuals of Agave tequilana.

El género Agave pertenece a la familia Agavaceae y cuenta con alrededor de 200 especies, con diversos usos. Agave tequilana es una de las especies más importantes a nivel industrial en México, ya que los azúcares que se acumulan en sus tallos son usados para producir la bebida alcohólica llamada tequila. La producción de agave es soportada por una intensiva propagación clonal y supresión de la reproducción sexual, lo cual ha conducido a reducción en la variabilidad genética y mayor susceptibilidad a plagas y enfermedades en plantaciones comerciales. No obstante, este estudio con plantas de un campo de cultivo del Estado de Guanajuato, México, llevado a cabo con marcadores AFLP, muestra que existen diferencias a nivel molecular entre hijuelos y bulbillos producidos asexualmente provenientes de la misma planta madre (75.08 % y 86.06 % de loci polimórficos, respectivamente). Aunque se observa un nivel significativo de polimorfismo entre hijuelos de rizoma, los niveles son aún más altos entre bulbillos con valores comparables a los encontrados entre plantas producidas por semilla (90.1 %). Por ello se propone un estudio más detallado de los factores que están causando la variabilidad genética entre individuos de Agave tequilana propagados asexualmente.

The in vitro reaction of S. rolfsii to five fungicides used for its control was evaluated. Five isolates of S. rolfsii from three localities of Guanajuato state, one from Colima and another from Morelos, Mexico were tested with the fungicides tebuconazole (1.25 g.i.a/L), thiabendazole and TCMTB (4.0 of g.i.a./L), procymidone, and iprodione (3.33 of g.i.a./L). A completely randomized experimental design with a factorial arrangement and five replications was used. Multiple mean comparison was done with Tukey's test (P < 0.05). The variables recorded were the effect of each fungicide on micelial radial growth, sclerotia production, the percentage of sclerotia viability, and vigor growth. The results showed little variability in sensitivity of isolates to the fungicides tested. The isolates displayed fungistatic effect or delayed micelial growth and reduction in number of sclerotia when treated with thiabendazole, procymidone and iprodione. Tebuconazole and TCMTB were fungicidal and inhibited mycelial growth and sclerotia production.

Se evaluó la respuesta in vitro de S. rolfsii a cinco fungicidas usados para su control. Se usaron cinco aislados del hongo provenientes de tres localidades del estado de Guanajuato y uno de cada uno de los estados de Colima y Morelos, México, los cuales se confrontaron a los fungicidas tebuconazole (1.25 g.i.a/L), thiabendazole y TCMTB (4.0 g.i.a./ L), procimidone e iprodione (3.33 g.i.a./L). Se utilizó un diseño experimental completamente al azar, con arreglo factorial, con cinco repeticiones. La comparación múltiple de medias se realizó con la prueba de Tukey (P < 0.05). Se registró el efecto de cada fungicida sobre el crecimiento radial micelial, la producción de esclerocios, el porcentaje de la viabilidad de esclerocios producidos y el vigor de crecimiento del hongo. Los resultados mostraron que existe poca variabilidad en los patrones de sensibilidad a fungicidas dentro de los aislados evaluados; asimismo, éstos presentaron efecto fungistático o retraso en el crecimiento micelial y reducción en el número de esclerocios con thiabendazole, procimidone e iprodione. Tebuconazole y TCMTB tuvieron un efecto fungicida inhibiendo el crecimiento micelial y la producción de esclerocios de los aislados.

Garlic (Allium sativum) is affected by a complex of different viruses. The objective of this investigation was to identify viruses in garlic plants from ten locations and to determine their effect on agronomic characteristics and quality of garlic. Bulbs from the variety Taiwan were collected from apparently healthy plants and plants with virus symptoms. Two independent experiments were conducted. In the first, one height, diameter, bulb weight, and number of bulbils per bulb were evaluated. In the second experiment, the same parameters were evaluated, but the overall plant health, plant height, number of leaves per plant, and virus symptoms were included. The frequency and relative concentration of Leek yellow stripe virus (LYSV), Onion yellow dwarfvirus (OYDV), Garlic common latent virus (GarCLV), and Shallot latent virus (SLV) were also evaluated using the DAS-ELISA technique. The four viruses were present in all ten locations. The potyvirus LYSV and OYDV showed a frequency of 96.5 and 84.4%, respectively, while the carlaviruses GarCLV and SLV showed 87.5 and 81.0%, respectively. The results indicate that the viral complex present in garlic affects detrimentally the agronomic and quality characteristics of garlic in the ten localities were the study was conducted.

El ajo (Allium sativum) es afectado por un complejo de diferentes virus. El objetivo de esta investigación fue identificar los virus en plantas de ajo de diez localidades y determinar su efecto sobre características agronómicas y calidad del ajo. Se seleccionaron bulbos de la variedad Taiwán, de plantas aparentemente sanas y plantas con síntomas virales. Se realizaron dos experimentos independientes: en el primero se determinó la altura, diámetro y peso de bulbo y número de bulbillos por bulbo. En el segundo se analizaron las mismas variables, más la sanidad, altura de planta, número de hojas por planta y la sintomatología de virosis. También se evaluó la frecuencia y concentración relativa de los virus Leek yellow stripe virus (LYSV), Onion yellow dwarf virus (OYDV), Garlic common latent virus (GarCLV) y Shallot latent virus (SLV), utilizando la técnica DAS-ELISA. Los cuatro virus estuvieron presentes en las localidades estudiadas; los potyvirus LYSV y OYDV con una frecuencia del 96.5 y 84.4%, respectivamente y los carlavirus GarCLV y SLV con una frecuencia del 87.5 y 81.0%, respectivamente. Los resultados muestran que el complejo viral presenta un efecto detrimental sobre las características agronómicas y de calidad del ajo en las diez localidades del estudio.

The enzyme-linked immunosorbent assay technique (ELISA) was used to identify the causal agents of virus diseases on garlic in the state of Guanajuato, Mexico. Tests were carried out to detect the presence of GarCLV Garlic common latent virus, LYSV Leek yellow stripe virus, OYDV Onion yellow dwarf virus, and SLV Shallot latent virus. A total of 80, 85, and 30 garlic leaf samples were analyzed in the first, second, and third samplings respectively, yielding a total of 195 samples. Two samplings were made in the counties of San Miguel de Allende (40 samples:), San Luis de La Paz (15) and Valle de Santiago (40), whereas three in counties Salamanca (30), and Villagriin (70).The presence of the four viruses on garlic plant samples from all counties sampled was confirmed. The order of frequency was OYDV with 63%. LYSV 60.5%, GarCLV, 32.3%, and SLV 21.0%. A previous work reported the presence of viruses from the potyvirus group; this is the first work carried out with individual viruses on garlic plants in Mexico.

Se utilizó la técnica de inmunoabsorción con conjugados enzimáticos (ELISA) para la identificación de los agentes causales de las enfermedades de origen viral en ajo del estado de Guanajuato, México. Se realizaron pruebas para la detección de los virus Virus latente común del ajo (GarCLV Garlic common latent virus). Virus del rayado amarillo del puerro (LYSV Leek yellow stripe virus), Virus enanismo amarillo de la cebolla (OYDV Onion yellow dwarf virus) y Virus latente del shallot (SLV Shallot latent virus). Se analizaron 80. 85 y 30 muestras de follaje de plantas de ajo en el primero, segundo y tercer muestreos, respectivamente, con lo cual se tuvieron I9S muestras totales en las tres fechas de evaluación. Se realizaron dos muestreos en los municipios de San Miguel de Allende (40 muestras), San Luis de La Paz (15) y Val le de Santiago (40) y tres en los municipios de Salamanca (30) y Villagrán (70), Guanajuato. Se confirmó la presencia de los cuatro virus en follaje de plantas de ajo en todos los municipios muestreados. Los virus detectados en orden de frecuencia fueron OYDV con un 63%, LYSV 60.5%, GarCLV 32.3% y SLV con un 21%. Este es el primer estudio que se realiza sobre virus individuales en ajo en el país, ya que anteriormente se había reportado al grupo de Potyvirus.