Efficient plant regeneration from multiple shoots formed in the leaf-derived callus of Lavandula vera, using the "open culture system".
Abstract To develop an efficient procedure for plant regeneration from leaf-derived callus of Lavandula vera DC, the production of multiple shoots and the formation of roots from these shoots were studied. When calli were cultured in a medium with 4.0×10−7 M N-(2-chloro-4-pyridyl)-N′-phenylurea (CPPU), urea-type cytokinin, multiple shoots were obtained from the greenish surface of the callus efficiently at a rate of 52.2%. For multiple shoot development, the shoots were divided into 7–20 shoot clusters with 2–3 shoots and subcultured every 2 weeks. Two modified culture-systems were employed for subculture; a “closed culture system” and an “open culture system”. In the open-system, shoot clusters grew and elongated vigorously. In the closed-system, most of the clusters showed vitrification and did not elongate. In root induction culture, shoot clusters in the open-system were well rooted and grew vigorously, the highest rate of root formation being 74.0%, in the 1 2 MS medium supplemented with 1.0×10−6 M indoleacetic acid (IAA). On the other hand, shoot clusters in the closed-system showed vitrification and did not root well. About seven times more regenerants were obtained from the multiple shoots than from normal shoots treated with 4.4×10−6 M 6-benzylamino purine (BA), a purine-type cytokinin. These results indicate that efficient plant regeneration in L. vera from callus using multiple shoots is possible by means of an open-system.
A Rapid and Efficient Protocol for Clonal Propagation of Phenolic-Rich Lavandula multifida
Lavandula multifida (fernleaf lavender) grows in confined regions of Portugal. This species is known for its interesting chemical profile, rich in phenolic compounds, and significant antifungal and anti-inflammatory properties, making it an interesting plant for industrial exploitation and justifying alternative propagation methods. Therefore, the present study aims the development of an efficient protocol for large scale propagation of this species, assuring plant uniformity and aiming a sustainable industrial exploitation with preservation of natural resources. In vitro cultures were established on Murashige and Skoog medium (MS) with different concentrations of benzyladenine (BA) and zeatin (ZEA). Best multiplication rates (6.14 shoots per explant) were achieved using MS supplemented with 1.0 mg/L ZEA and rooting occurred spontaneously on the propagation medium avoiding additional rooting steps. Moreover, plants flowered during the acclimatization phase, confirming a more rapid in vitro development and shorter breeding cycle. This is a very interesting aspect for essential oil extraction. Trichome morphology was examined by scanning electron microscopy and the secretion analyzed through histochemical tests. Trichomes of micropropagated plantlets were identical to those of field-growing plants, and essential oil production was observed at early stages of development. The present study confirms that micropropagation under controlled conditions could be an interesting alternative for field production of L. multifida, since higher amounts of plants can be obtained in less time with guarantee of genetic stability and phytossanitary quality, very important features regarding essential oil production and commercialization.
Modelling of Reactors for the Thermal Treatment of Waste and Biomass
Modelling of reactors devoted to the thermal treatment of waste and biomass is a very complex task. It has to represent the physical and chemical phenomena occurring at different scales with a feedstock which is often neither completely known nor homogeneous. The first difficulty to overcome is associated to the description of the intrinsic reaction pathway of the pyrolysis reaction (which is at the center of the overall thermal treatment) and its associated kinetics. Indeed, a mathematical model has to be built to compute the rate of consumption of the initial and infinitesimal (but representative) material, the rate of production of the products of reaction as well as their nature. It has to be pointed out here that this first model should be respectful of atom balances during the overall operation. The second point that as to be addressed deals with heat and mass transfer that occur within the particle undergoing reaction. Indeed, as heat is provided to this particle, its temperature increases and when it becomes sufficient, chemical reaction begins (without any other requirement in the case of pyrolysis, or if co-reactant is also present in the case of gasification or combustion) leading to heat and mass production/consumption. These new products must be transported outside of the reactive particle under the effect of internal pressure gradients and diffusion. Then, when they have been released from the particle their future will depend upon their surrounding environment and more precisely upon the nature of the reactor (single particle, fixed bed, fluidized bed…) which will be relevant on the estimation of the extra heat and mass transfer. This short description illustrates the fact that modeling reactors for thermal treatment of biomass requires to describe several phenomena. In this paper, we focus on a multiscale description of the relevant processes involved in the overall transformation. As a starting point, the intra particle scale is considered. Some insights into possible modelling concepts at this step are provided. Then, the particle scale is described. Once again, the important phenomena as well as the modeling options are discussed. Finally, the reactor scale is considered. These previous considerations are applied to the descriptions of model that have been developed in the case of refuse derived fuel grate gasification, combustion of sludge in a fluidized bed and pyrolysis of biomass in a fixed bed.