Indirect organogenesis for high frequency shoot regeneration of two cultivars of Sansevieria trifasciata Prain differing in fiber production.

Sansevieria trifasciata is used as an indoor plant, in traditional medicine and as a fiber source. Here we characterized fibers of two of varieties of S. trifasciata, Lorentii and Hahnii, and report a protocol for their propagation based on indirect shoot organogenesis. Structural and ribbon fibers were scattered within leaf parenchyma when viewed with confocal laser scanning microscopy. Chemical analysis of the fibers by mass spectrometry and high-performance chromatography revealed higher contents of cellulose and xylose in Lorentii than in Hahnii and significant differences for total lignin between both. A protocol for de novo shoot production was then developed using leaf explants. Time-course histological analyses showed that the first events of transdifferentiation were triggered preferentially in cells surrounding fibers and vascular bundles. Callogenesis and shoot performances were quantified for both varieties, and 2,4-D at 2 and 3 mg·L-1 yielded the best results for primary calli induction and fresh calli mass. The length, number, and mass of shoots produced did not differ significantly between the two cultivars. The fast morphogenic response of S. trifasciata to in vitro culture may be useful for mass propagation or other biotechnological purposes such as metabolite production.

Bark water storage capacity influences epiphytic orchid preference for host trees.

PREMISE: Of all orchid species described, 70% live on phorophytes. Trees offer a vital space with characteristics that influence the successful establishment and life cycle of orchids. Field inventory and distribution analysis suggest that phorophyte selection is biased to certain tree species that would serve as better hosts. Phorophyte bark is known as an important factor that influences this preference, but the chemical and physical properties of bark that contribute to creating a favorable space for orchids are still poorly understood. In this work, the effect of bark physical characteristics on phorophyte preference of tropical orchids was studied. METHODS: Orchids and their phorophytes were counted and identified along transects inside two natural reserves in Southeast Mexico. A rhytidome classification was used to describe the bark decoration patterns of the phorophytes. To quantify bark fissuring, we developed a new protocol based on image processing of light micrographs using free-access software. Bark topology characterization was complemented with scanning electronic microscopy. Maximum and minimum water content was also determined. RESULTS: Analyses of bark decorations and bark fissuring were not enough to explain the preference found for some tropical trees. In contrast, a positive relationship was found among water-storage capacity, bark porosity, and phorophyte preference. The host trees preferred by most orchids have bark with higher pore density and higher water retention after draining. CONCLUSIONS: Unexpectedly, the phorophytes preferred by orchids are not those with more fissured bark but those with a higher ability to retain minimum water content after draining, which is a bark property positively correlated with higher pore density. Our data indicate that the bark microenvironment, determined by topology and water storage capacity, has a pivotal role in phorophyte specificity, a key factor that affects orchid diversity and distribution in the world.

Designing and evaluation of urea microcapsules in vitro to improve nitrogen slow release availability in rumen.

BACKGROUND: There is a growing interest in the development of novel and innovative vehicles for controlled release of urea into the rumen, aiming to provide ammonia-N for the biosynthesis of proteins of bacterial origin and to prevent urea intoxication by direct feeding to livestock. Urea microencapsulation is a system that can control the release of urea to be slow and steady. RESULTS: The amount of encapsulated urea was 69% of CSU (calcium silicate + urea + Eudragit RS100® + dichloromethane) and 71% of ACU (activated charcoal + urea + Eudragit RS100® + dichloromethane) groups (p > 0.05) The buoyancy of the microcapsules was over 50% after 12 h of agitation in both groups (CSU and ACU), producing significant differences in the volume of the organic phase factor, which was 20 mL at the lowest value (p = 0.0005). The morphology of the microcapsules produced with CSU and ACU showed no significant differences in microcapsule morphology (p > 0.05). The lower temperature (35 versus 40 °C, p = 0.035) retained better morphology of the microcapsules. Regarding the in vitro ammonia-N release kinetics, unprotected urea reached a maximal peak after 6 h, while CSU and ACU took more than 24 h to reach ammonia-N released concentration. CONCLUSIONS: We stabilized the physical factors in the microencapsulation of urea that can allow slow release of rumen fluid. © 2018 Society of Chemical Industry.

Intercambio de gases y relaciones hídricas durante el retraso de la senescencia foliar de trigo (Triticum aestivum L) por la citocinina bap / Gas exchange and water relations during delay of leaf senescence in wheat (Triticum aestivum L) by cytokinin bap

Se estudió el efecto de la citocinina 6-bencilaminopurina (BAP) en el intercambio de gases y relaciones hídricas de Triticum aestivum L. durante el retraso de la senescencia foliar en invernadero. Plántulas de 21 días después de la siembra (DDS) fueron asperjadas con BAP 0,1mM o agua (testigo) cada 3 días por 20 días. El retraso de senescencia foliar en las plantas tratadas con BAP fue monitoreado mediante cuantificación de clorofila y proteína soluble total. El intercambio de gases se estimó mediante conductancia estomática (gs) y tasa de fijación de CO2. Las relaciones hídricas se evaluaron midiendo el potencial de agua total (YA) y sus componentes, osmótico (Ys) y de turgencia (Yt), cada 5 días por 20 días. Las hojas con BAP mostraron mayor concentración de clorofila y proteína total que el control tras 26 DDS, diferencias que aumentaron con el tiempo y a los 41 DDS fueron 7 veces mayores que el control. La gs registró valores no significativamente diferentes al estado verde pre-senescente. Estas respuestas se asociaron con tasas mayores de fijación de CO2, con concentraciones cercanas a las hojas verdes pre-senescentes (6,2μmol·CO2·m-²·s-¹). El YA se mantuvo constante bajo BAP y Ys fue significativamente menor que en los testigos, favoreciendo la retención de solutos en el citoplasma de hojas con retraso de senescencia. El Yt de las hojas tratadas fue mayor que su respectivo testigo de 31 a 41 DDS. Por tanto, la citocinina BAP promovió el mantenimiento de la tasa de fijación de CO2 y las relaciones hídricas durante el retraso de la senescencia foliar.