IT is rare, even in these days of specialized studies, that circumstances permit an investigator to present a 'first book' on pioneer work in any subject. This opportunity has come to Dr. White, and he has taken full advantage in the presentation of an admirable book. In the past, text-books of, tissue culture have given the quite erroneous impression that only animal biologists have any interest in the subject or could derive anything of value from its study. Dr. White presents the case of the plant biologist, based on 457 references, with commendable force. He compresses into this relatively small volume the 'high spots' of plant tissue culture up to the present, in which he has himself played an outstanding part, and points out wide fields of interest for future research. A Handbook of Plant Tissue Culture By Dr. Philip R. White. Pp. xiv + 277. (Lancaster, Pa.: The Jaques Cattell Press, 1943.) 3.75 dollars.

A Handbook of Plant Tissue Culture

The concept of a thin cell layer (TCL) was initially presented by Tran Thanh Van in two key papers exactly 40 years ago. At that time, Nicotiana tabacum was the model plant used to establish three main pathways for de novo organogenesis by developing a flower, vegetative bud, and root “programme” from pedicel tissue. Over the last 40 years, a wealth of research in plant tissue culture based on TCLs has emerged, fortifying the importance of this very simple technique, and highlighting its fundamental importance as a key tool in plant cell and tissue differentiation as well as organ development. This review not only highlights the achievements made using TCLs in the plant kingdom over these 40 years, it also reports on the success of this technique in ornamentals, fruit and forestry species, vegetables, and medicinal plants. There is overwhelming evidence of the importance of this technique for plant biotechnology, and it provides one solution for the mass clonal propagation of plants, use in bioreactors, genetic transformation, or micropropagation.

Plant Thin Cell Layers: A 40-Year Celebration

An improved and efficient micropropagation of Eclipta alba through transverse thin cell layer culture and assessment of clonal fidelity using RAPD analysis

The present work describes a procedure that allows for the easy and rapid induction of caulogenesis in four cultivars of Brassica napus L. from transversal Thin Cell Layers (tTCLs). In order to investigate the regeneration ability of this crop, the effects of genotype, explant source and culture medium were examined on shoot regeneration. The tTCL explants were excised from hypocotyl and petiole of 2-week-old seedlings and cultured on a solid basal MS medium supplemented with α-naphthaleneacetic acid (NAA: 0.1–0.4 mg l−1), 6-benzylamino-purine (BAP: 1–4 mg l−1) and sucrose (20–40 g l−1). A significant genotypic effect was observed between the four cvs; Jumbo and Drakkar displayed higher capacities to produce shoots than Pactol and Cossair. Regeneration commenced earlier and the percentage of shoot-producing explants as well as the number of shoots per regenerating explant was greater. The comparison between the regeneration ability of different explants showed that the hypocotyls exhibited a high rate of shoot organogenesis when they were cultured on MS medium supplemented with 3 mg l−1 BAP, 0.3 mg l−1 NAA and 30 g l−1 sucrose. Adventitious shoot buds developed from 46% of the tTCLs, with a mean of 7.5 buds. Furthermore, the method was fast with shoot formation occurring by 7 days culture. Plantlets regenerated from all shoots and developed normally. The regenerated plants were fertile and identical to source plants.

Rapid shoot regeneration from thin cell layer explants excised from petioles and hypocotyls in four cultivars of Brassica napus L.

An efficient and improved in vitro propagation system for Spilanthes acmella L. using transverse thin cell layer (tTCL) culture system was established. The frequency of shoot regeneration from tTCL nodal segments was affected by concentrations of plant growth regulators and orientation of the explant. MS (Murashige and Skoog in Physiol Plant 15:473–497, 1962) medium with 5.0 mg dm−3 BAP was optimal for shoot regeneration. Upon this medium, the explant inoculated in the upright orientation exhibited a high frequency of shoot regeneration (about 97%), and the highest number of shoots (31.5) per explant. The intact node (1.0–1.5 cm) cultured on the same medium had significantly lower shoot multiplication ability with only 4.5 shoots per responsive explant. As compared to BAP alone, the combination of BAP and Kin or NAA did not have positive effects on shoot multiplication from tTCL nodal segments. Rooting of shoots was achieved on growth regulator free full-strength MS medium. Plantlets were transplanted into soil with 90–100% survival rate.

An improved micropropagation of Spilanthes acmella L. through transverse thin cell layer culture

Caulogenesis and somatic embryogenesis were induced from transverse thin cell layers (tTCLs) of two European (Spinacia oleracea L) spinach genotypes Regeneration occurred mostly when tTCLs had been excised from seedlings grown on a preconditioning medium consisting of White's macroelements, Nitsch's microelements, Murashige and Skoog's (MS) vitamins, 6 g l−1 agar and 20 g l−1 glucose The explants were cultured on MS medium supplemented with sucrose (10, 30, 50 or 80 g l−1) or fructose (5, 10 or 30 g l−1) and several combinations of indole-3-acetic acid (IAA), α-naphtalene acetic acid (NAA), 6-benzylaminopurine (BAP) and gibberellic acid (GA3) Most of the regeneration events were obtained from root explants of the cultivar Carpo The best result was observed on MS medium supplemented with 50 g l−1 sucrose, 100 μM NAA, 1 μM BAP and 10 μM GA3 After an 8-week culture, the calluses were transferred onto MS medium where shoots and somatic embryos appeared 1 week later The best root development was obtained on MS medium supplemented with 49 μM indole-3-butyric acid (IBA) and 8 g l−1 Phytagel The plantlets were, then, transferred to soil and developed into well-conformed, fertile plants

Stéphanie Leguillon

Papers

Plant regeneration from thin cell layers in Spinacia oleracea