Stefaan P.O. Werbrouck

• Ph.D.
• Ghent University

Fluorinated cytokinins have emerged as promising alternatives to traditional cytokinins in plant tissue culture, offering enhanced stability and bioactivity. However, their metabolic fate and impact on endogenous cytokinin profiles remain largely unexplored. This study investigated the cytokinin metabolism of Phalaenopsis orchids under varying exog...

Securidaca longepedunculata Fresen. is an overexploited forest species in the Lubumbashi region (south-eastern DR Congo), as its roots are highly valued in traditional medicine. Conventional propagation of this species is affected by seed dormancy and a high mortality rate during early seedling development. To improve on existing methods, we develo...

Trans‐resveratrol is a natural polyphenolic compound, belonging to the class of stilbenes. It is known for its various pharmacological properties but limited bioavailability. Our objective was to evaluate for the first time the effect of an extract of Sargassum vulgare on resveratrol, piceatannol and piceid production in peanut (Arachis hypogaea) s...

Recovering biostimulant compounds from by-products of crops is a promising strategy to add value, enhance sustainability, and increase the environmental safety of the agricultural production chain. Here, we report consistent root and shoot growth-stimulating bioactivity present in water-based extracts from Belgian endive forced roots ( Cichorium in...

An efficient regeneration protocol was applied to regenerate shoots on salt stress-tolerant calli lines of aubergine (Solanum melongena). These NaCl-tolerant cell lines were obtained by two different methods. On the one hand, the developed callus tissue was transferred to a medium with a continuous salt content of 40, 80, 120, or 160 mM NaCl. On th...

Previously, an efficient regeneration protocol was established and applied to regenerate plants from calli lines that could grow on eggplant leaf explants after a stepwise in vitro selection for tolerance to salt stress. Plants were regenerated from calli lines that could tolerate up to 120 mM NaCl. For further in vitro and in vivo evaluation, four...

The present invention relates to plant extracts and their use as biostimulant and biocontrol agent. More specific, the invention provides extracts of plants of the genus Helianthus which are capable of modifying root architecture and stimulate root development in plants. Hence, said extracts can be used to control plant development such as e.g. imp...

Stevia rebaudiana, which produces the non-caloric natural sweeteners referred to as steviol glycosides (SGs), is a perennial herb native to South America. This study examines the effect of various biotic elicitors, including chitosan (CH) and yeast extract (YE), as well one abiotic elicitor, namely methyl jasmonate (MeJA), on in vitro shoot multipl...

Although micropropagation in temporary immersion systems might increase plant growth and multiplication, it can also cause specific problems such as hyperhydricity and losses by contamination. A new commercial temporary immersion bioreactor, SETIS™, was used to micropropagate two Tunisian pear cultivars, 'Arbi' and 'Mahdia 6'. The latter cultivar w...

Industrial chicory (Cichorium intybus L.) is mainly grown for inulin production. To enhance production and uniformity, hybrid cultivars are preferred. Therefore, a controlled pollination system and homozygous parental lines are needed. The most desirable pollination control system is cytoplasmic male sterility (CMS). A new, naturally induced CMS ha...

The Mycelium Donor Plant system (MDP) was adapted to study the time course of the colonization of Pyrus communis by Rhizophagus irregularis under in vitro conditions. Isolated germinated spores did not colonize pear roots. Inoculum composed of R. irregularis spores/mycelium associated with chicory root fragments was used to inoculate Medicago trunc...

In vitro propagation of the ornamentally interesting species Wikstroemia gemmata is limited by the recalcitrance to form adventitious roots. In this article, two strategies to improve the rooting capacity of in vitro microcuttings are presented. Firstly, the effect of exogenous auxin was evaluated in both light and dark cultivated stem segments and...

Intergeneric hybridization between industrial chicory (Cichorium intybus L.) and Cicerbita alpina Walbr. induces interspecific hybrids and haploid chicory plants after in vitro embryo rescue. The protocol yielded haploids in 5 out of 12 cultivars pollinated; altogether 18 haploids were regenerated from 2836 embryos, with a maximum efficiency of 1.9...

Natural alloplasmic cytoplasmic male sterile (CMS) clones of industrial chicory were obtained after crossing wild chicory with selected breeding lines. We investigated the CMS stability of 10 clones in various environmental growing conditions. CMS was stable under cool growing conditions in most of them. Fertility restoration, based on pollen produ...

Leafy gall syndrome is the consequence of modified plant development in response to a mixture of cytokinins secreted by the biotrophic actinomycete Rhodococcus fascians. The similarity of the induced symptoms with the phenotype of plant mutants defective in strigolactone biosynthesis and signalling prompted an evaluation of the involvement of strig...

Significance The regeneration of entire plants from explants is an important step in plant production and plant transformation protocols. Despite recent advances in the knowledge on the molecular basis of regeneration, many aspects of the process and the causes of regeneration recalcitrance are still poorly understood. We combined linkage with asso...

The manuscript details the development of an in vitro model plant system using detached leaves because there is a need for biosynthetic methods for the production and isolation of masked mycotoxins. This detached leaf in vitro model was firstly applied to deoxynivalenol with satisfying results. The biosynthesis of deoxynivalenol-3-glucoside was con...

Plant regeneration through de novo shoot organogenesis in tissue culture is a critical step in most plant transformation and micropropagation procedures. Establishing an efficient regeneration protocol is an empirical process and requires optimization of multiple factors that influence the regeneration capacity. Here, we review the molecular proces...

An important application of chemicals in plant biology is their use as plant growth regulators in in vitro plant tissue culture. In vitro propagation mainly relies on two classes of plant growth regulators: cytokinins and auxins. Together, they regulate cell proliferation and differentiation and are used to induce shoot or root organogenesis. Besid...

Zearalenone-4-β-d-glucopyranoside (zearalenone-4-glucoside) detection techniques, based on a combination of acidic or enzymatic hydrolysis of the masked mycotoxin to the parent form (i.e. zearalenone), and immunochemical determination of zearalenone-4-glucoside as a difference between the zearalenone concentration after and before cleavage of the g...

In vitro shoot regeneration is implemented in basic plant research and commercial plant production, but for some plant species still difficult to achieve by means of the currently available cytokinins and auxins. To identify novel compounds that promote shoot regeneration, we screened a library of 10,000 small molecules. The bioassay consisted of a...

The effects of monochromatic blue, red and far-red light from commercial available light-emitting diode modules on the in vitro growth of Ficus benjamina 'Exotica' were compared with the effect of fluorescent light. The plants were micropropagated on a basal medium with 0.5 mg/L IAA and 2 mg/L BA. Our study showed that monochromatic blue, red and f...

The leaves of the Paraguayan herb Stevia rebaudiana Bertoni contain at least 30 steviol glycosides (SVglys), of which ST, Reb A, Reb C and Dul A accumulate the most. The accumulation of these SVglys occurs within different plant parts and is dependent on numerous environmental, agronomic and physiological factors. It is generally known that the gre...

CUP SHAPED COTELYDON 2 (CUC2) was tested as a marker for shoot induction to monitor and facilitate the optimization of in vitro regeneration of Arabidopsis thaliana. The expression of a pCUC2::3XVENUS-N7 fluorescent marker allowed the observation of early steps in the initiation and development of shoots on root explants. The explants were first in...

Chestnut (Castanea sativa Mill.) is difficult to propagate by grafting and cuttings. However, as an alternative to conventional vegetative propagation methods, efforts have been made to establish reliable in vitro regeneration systems that allow clonal propagation. The two major systems are based on embryogenesis and on micropropagation of axillary...

Factors affecting conversion of horse chestnut (A. hippocastanum L.) somatic embryos into plantlets were evaluated. Anther filament derived embryogenic tissue developed bipolar structures with two cotyledons and a well-developed shoot and root apical meristem upon auxin omittance from the culturing medium. The impact of carbohydrate type (glucose,...

The metabolism and the in vitro effects of the cytokinin N6-(3-hydroxybenzyl)adenine (meta-topolin, mT) were compared with those of N6-benzyladenine (BA), N6-benzyl-9-(2-tetrahydropyranyl)adenine (BPA) and N6-benzyladenine-9-riboside ([9R]BA) in micropropagated Spathiphyllum floribundum Schott cv. Petite. In vitro, BA, BPA and [9R]BA were mainly co...

Vital protoplasts from Spathiphyllum wallisii ‘Alain’ and Anthurium scherzerianum ‘238’ were isolated from both somatic embryos and leaves. The highest yields were obtained when 1.5% cellulase, 0.5% macerase and 0.5% driselase were used for Spathiphyllum wallisii leaves and 0.5% cellulase, 0.3% macerase and 0.5% driselase for Anthurium scherzerianu...

Somatic embryogenesis could represent a way to clonally propagate mature elite trees of horse chestnut. However, while a number of protocols describe successfully the induction and proliferation of somatic embryos a low frequency of embryos converted successfully into plants. The objective of this research was to identify a maturation medium that c...

A method for regeneration of plants from tuber explants of a Zantedeschia hybrid via somatic embryogenesis was developed. In vitro cultures were initiated starting from both anthers and tubers. Somatic embryogenesis was only achieved from tuber explants. 6-Benzyladenine (BA) at 0.6 or 2 mg l−1 in combination with 2 mg l−1 α-naphthaleneacetic acid (...

Polyploid Spathiphyllum wallisii Regel 'Speedy' plants were obtained from somatic embryos induced on anther filaments exposed to mitosis inhibitors. Primary embryos yielded less polyploid plantlets than secondary embryos. Colchicine could be efficiently replaced by oryzalin or trifluralin (10 µM), resulting in an average yield of 5% polyploids. The...

Dark germinated Arabidopsis thaliana Ler seedlings grown on medium with the commonly used imidazole-type fungicide imazalil (IMA) resemble de-etiolated (det) brassinosteroid-deficient mutants. IMA hampers cell elongation in the hypocotyl, but stimulates radial expansion during dark growth. This phenotype could partially be restored by simultaneous...

In Spathiphyllum wallisii the production of doubled haploids was attempted. Different combinations of growth regulators were tested, as well as different cultivars. The use of TDZ (0.25–1 M) in ovary cultures of Spathiphyllum was required. On the contrary, cytokinins were not crucial during ovule culture; in fact, the use of a too high TDZ concentr...

Recently interesting organogenic and morphogenic effects on micropropagated plants have been achieved by applying pesticides to the culture medium or by infesting plants with Rhodococcus fascians. Both interventions result in cytokinin-like effects (abundant shoot and bud formation), but in neither case it could be proven that cytokinins are direct...

Rhododendron simsii Hellmut Vogel was regenerated using different types of explants, auxins and cytokinins. After a callus induction phase, with 2,4-dichlorophenoxyacetic acid or -naphthaleneacetic acid, adventitious shoot regeneration was obtained on a medium supplemented with thidiazuron or zeatin. With thidiazuron shoots were small and a subsequ...

The imidazole fungicides imazalil, prochloraz, and triflumizole and the triazole growth retardant paclobutrazol strongly enhanced the shoot-inducing effect of 6-benzyladenine in Spathiphyllum floribundum ‘Petite’ Schott. Numerous small shoots and shoot meristems appeared at the basal part of the plant. This effect was confirmed when such widely dif...

Imidazole fungicides such as imazalil, prochloraz, and triflurnizole and the triazole growth retardant paclobutrazol promote the shoot-inducing effect of exogenous cytokinins in Araceae, such as Spathiphyllum floribundum Schott and Anthurium andreanum Schott. The mechanism of their action could partially be based on the inhibition of gibberellic ac...

In Spathiphyllum floribundum 'Petite', which was cultured on medium containing benzyladenine (BA), uptake of this cytokinin and its conversion to 9-ß-D-ribofuranosyl-benzyladenine (9R-BA) or 9-ß-glucopyranosyl-benzyladenine (9G-BA) was monitored. BA and extremely large quantities of 9G-BA were exclusively located in the basal part of the plant (cal...

In Spathiphyllum floribundum ‘Petite’ Schott shoot induction by benzyladenine (BA) was enhanced dramatically by adding the imidazole fungicide imazalil to the medium. As the concentration of imazalil increased, the number of shoots increased, and finally their size was reduced to a small meristematic dome. An average of 127 shoots/ expiant develope...