Dipti Tonk

Elicitors Enhance Alkaloid Yield in Catharanthus roseus

Catharanthus roseus (L.) G. Don is an important plant of medicinal importance. A number of active compounds of this plant are anti-cancerous in nature. Two such compounds are vinblastine and vincristine; unfortunately, the level of these phytocompounds is very low. In this chapter, the influence of elicitation, one of the important biotechnological techniques, has been discussed for improving yield. Elicitation, the elicitor types, the role of biotic and abiotic elicitors, and molecular mechanism of elicitation have also been described by presenting elicitation model in C. roseus. Besides, the importance of in vitro culture, the role PGRs, precursor feeding, and other factors that have some role in enriching yield have also been highlighted.

In vitro propagation of Althaea officinalis :the role of plant growth regulators in morphogenesis

Althaea officinalis L. (marshmallow) belonging to the Malvaceae family, is an important plant that contains a variety of important phytocompounds including asparagine, pectin, flavonoids, polyphenolic acid, and scopoletin. The yield of these compounds can be improved using biotechnological methods that allow for a steady and continuous regeneration of plant material. To the best of our knowledge, thus far, the in vitro clonal multiplication of marshmallow has not been attempted on a large scale. Therefore, in this study, we developed callus induction and multiple shoot regeneration protocols from explants. All the explants, i.e., roots, nodes, and leaves, evoked compact white or yellow calli in a medium supplemented with 2,4-dichlorophenoxyacetic acid (2,4-D), which grew vigorously. The callus induction frequency was the highest (62.1%) from stem nodes, followed by leaves (39.1%) and roots (27.5%). The differential behavior of explants in response to various plant growth regulators (PGRs) was studied. The calli from leaves and roots were noted to be non-organogenic/embryogenic in media containing different PGR concentrations and have been described in this communication. The stem nodes used were cultured on MS media amended with different concentrations of benzyl-amino-purine (BAP: 0.5, 1.0, and 2.0 mg/l). Multiple shoots were formed at variable numbers, the maximum being in a medium supplemented with 1.0 mg/l of BAP. The induced shoots were rooted in IBA-, NAA-, and IAA-amended media, where IBA at 0.5 mg/l induced a maximum number of roots (8.8 roots/shoot). The regenerated plants were transferred to plastic pots, filled with soilrite and soil (1 : 1), and finally, transferred to outdoor conditions.

Embryogenesis in Ornamental Monocots: Plant Growth Regulators as Signalling Element

The process of in vitro embryogenesis has several basic and applied applications especially in fast and mass propagation of elite ornamental germplasm. In this chapter, somatic embryogenesis is described in two important ornamental plants. The select plants Gladiolus and Caladium are the monocot genera, belonging to the family Iridaceae and Araceae in which in vitro embryogenesis were investigated. Indirect somatic embryo formation was noticed in both the plants on tuber/rhizome callus. Although the synthetic auxin 2,4-D is a good signalling element in inducing embryos, the amendment of NAA and BAP improved embryogenesis and embryo numbers. The single use of BAP (0.5–1.0 mg/) was also effective in triggering embryogenesis; the embryo number was, however, low. The signalling and molecular role of auxin, cytokinin, GA3 and ABA in regulating somatic embryogenesis is briefly summarised. The origin, embryo structure and development are very similar, so was the requirement of plant growth regulator (PGR). The embryo structure and development was investigated morphologically, by using scanning electron microscopy (SEM) and is presented. The addition of 0.5 mg/l GA3 was noted to be very efficient in promoting embryo maturity; the influence of ABA in embryo maturation is also discussed. The technique of making synthetic seed in C. bicolor was made and is described briefly. The regenerative medium for obtaining plants from synthetic seeds was identified after storage at low temperatures (0 and 4 °C). The somatic embryos/synthetic seeds germinated into plantlets on 0.5 mg/l BAP-added medium and the regenerated plants are very similar to the mother plants. This and similar in vitro embryogenesis studies may help in building phylogenetic tree of near or distantly related taxonomic plants/plant groups.