Nor Azlina Hasbullah

Irradiation effect on in vitro organogenesis, callus growth and plantlet development of Gerbera jamesonii

The present work was carried out to study the effects of gamma irradiation on in vitro growth of explants, callus and the formation of shoots and plantlets. Irradiation is known to exhibit or inhibit the differentiation of cells and growth of plants in vitro, which helps in producing new plant varieties. Gamma irradiation is one of the physical mutagens that are widely used for mutation breeding. A gradual decline was observed in the number of shoots regenerated from irradiated petiole explants compared to control. Numbers of shoots regenerated from irradiated petiole explant cultured on Murashige & Skoog medium supplemented with 2.0 mg L-1 BAP and 0.5 mg L-1 NAA was reduced to 6.6±0.9 from 7.5±0.4 (control) when explants were exposed to 20 Gray of irradiation dose. Similar observation was reported on effects of gamma irradiation on in vitro propagated plantlets. Gradual decline was observed based on plant height as the dose of gamma irradiation increased. A significant decline was observed in the fresh weight of irradiated callus compared to control. In this case, growth responses of callus were strongly influenced by the radiation dose. The fresh weight of callus was reduced to 76.4±2.2% compared to 89.7±0.5% of control when callus tissues were exposed to 20 Gy.

Establishment of somatic embryogenesis from Gerbera jamesonii Bolus EX. Hook F. through suspension culture

Cell suspension cultures were established from embryogenic callus induced from leaf explants of Gerbera jamesonii Bolus ex. Hook f. Embryogenic callus was induced when leaf explants were cultured on MS medium containing 1.0 to 2.0 mg/L 2,4-D. Cream friable callus was formed within two weeks. Proliferated callus was transferred to MS liquid medium containing 2,4-D with a small concentration of NAA and subcultured at 2 weeks interval. Induction of somatic embryos (globular, heart and torpedo) was observed after 2 weeks of culture. Somatic embryos developed in MS suspension medium containing 1.0 to 2.0 mg/L 2,4-D with 0.1 or 1.0 mg/L NAA and globular embryos were further differentiated into the cotyledonary phase embryos. The addition of amino acids (L-glutamine or L-proline, 5.0 mg/L, respectively) to the culture media, in the range of concentrations tested, yielded higher enhancement of the embryo growth and development. Transfer of individual embryos onto a fresh basal medium with no plant growth regulators was able to achieve complete maturation. Relatively, only a few number of embryos developed shoots and roots when transferred to MS medium supplemented with 2.0 mg/L BAP and 0.5 mg/L NAA in addition to 3% (w/v) sucrose and 0.8% (w/v) agar containing medium. About 11% of somatic embryos were converted to true-to-type fertile plants.

Germination and Plantlet Regeneration of Encapsulated Microshoots of Aromatic Rice (Oryza sativa L. Cv. MRQ 74)

Plant tissues such as somatic embryos, apical shoot tips, axillary shoot buds, embryogenic calli, and protocom-like bodies are potential micropropagules that have been considered for creating synthetic seeds. In the present study, 3–5 mm microshoots of Oryza sativa L. Cv. MRQ 74 were used as explant sources for obtaining synthetic seeds. Microshoots were induced from stem explants on Murashige and Skoog (MS) medium supplemented with 1.5 mg/L benzylaminopurine (BAP). They were encapsulated in 3% (w/v) sodium alginate, 3% sucrose, 0.1 mg/L BAP, and 0.1 mg/L α-Naphthalene acetic acid (NAA). Germination and plantlet regeneration of the encapsulated seeds were tested by culturing them on various germination media. The effect of storage period (15–30 days) was also investigated. The maximum germination and plantlet regeneration (100.0%) were recorded on MS media containing 3% sucrose and 0.8% agar with and without 0.1 mg/L BAP. However, a low germination rate (6.67%) was obtained using top soil as a sowing substrate. The germination rate of the encapsulated microshoots decreased from 93.33% to 3.33% after 30 days of storage at 4°C in the dark. Therefore, further research is being done to improve the germination rate of the synthetic seeds.

Effects of NAA and BAP, Double-Layered Media, and Light Distance on In Vitro Regeneration of Nelumbo nucifera Gaertn. (Lotus), an Aquatic Edible Plant

In vitro direct regeneration of Nelumbo nucifera Gaertn. was successfully achieved from immature explants (yellow plumule) cultured on a solid MS media supplemented with combinations of 0.5 mg/L BAP and 1.5 mg/L NAA which resulted in 16.00 ± 0.30 number of shoots per explant and exhibited a new characteristic of layered multiple shoots, while normal roots formed on the solid MS basal media. The double-layered media gave the highest number of shoots per explant with a ratio of 2 : 1 (liquid to solid) with a mean number of 16.67 ± 0.23 shoots per explant with the formation of primary and secondary roots from immature explants. In the study involving light distance, the tallest shoot (16.67 ± 0.23 mm) obtained from the immature explants was at a light distance of 200 mm from the source of inflorescent light (1000 lux). The plantlets were successfully acclimatized in clay loam soil after 8 months being maintained under in vitro conditions.

Physiological Responses of Callus from Gerbera jamesonii Bolus ex. Hook f. to Gamma Irradiation

In the present study, in vitro mutagenesis techniques were applied to investigate the effects of gamma irradiation at 0, 10, 20, 30, 40, 50 and 60 Gy on physiological changes in callus of Gerbera jamesonii Bolus ex. Hook f. Biochemical changes in chlorophyll and soluble protein content of pre- and post- irradiated Gerbera callus were studied. Non-irradiated callus demonstrated the highest amount of chlorophyll content as compared to callus irradiated at 10, 20, 30, 40, 50 and 60 Gy. In addition, the amount of chlorophyll b was relatively higher than chlorophyll a in both the irradiated and non-irradiated callus, except for callus irradiated at 10 Gy. Biochemical differentiation based on total soluble protein content revealed gradual reduction after day 9 of exposure to gamma irradiation. Reduction of soluble protein content was observed in all the treatments as the increase of incubation period.

Natural paint production from anthocyanin extracts of Gerbera jamesonii Bolus ex. Hook F

Abstract Gerbera jamesonii (Asteraceae) is a flowering plant with increasing commercial significance. Today, this plant has become one of the leading cut flowers and ranks among the top 10 cut flowers in the world. It is known to contain a high percentage of anthocyanin. Gerbera petals can be a good colourant source and, potentially, a good source of antioxidants. Having potential for producing colourants, the focus of this research thus mainly aimed to extract anthocyanin pigments from fresh G. jamesonii petals and to study the optimum condition for natural paint production from the anthocyanin extracts. Petals from G. jamesonii were collected and dried. Extracts of Gerbera petals were prepared by extracting dried petals using 70% methanol. The extracts were then centrifuged at 5000 rev min−1 for 15 min, and the supernatant, anthocyanin, was used in the production of natural paint. Polyurethane was used as binder in the paint formulation. Higher concentrations of colourants have shown more stability with the addition of polyurethane in paint systems. The addition of 1% benzoic acid as a co-pigment enhanced the stability of the anthocyanin colour and the quality of the natural paint. In this work, an attempt was made to use natural products in the coating industry.