Induced mutagenesis using gamma ray has been proven applicable to improve varieties of many genotypes of crop species. The effects of 60Co gamma ray dosage on growth and callus induction of nucellus segments of Citrus reticulata cv. limau madu were investigated. The nucelli were exposed to gamma rays at doses of 10, 20, 40, 60, 80, 100 and 120 Gy, followed by embryogenic callus (EC) induction on Murashige and Skoog medium supplemented with 500 mg L-1 malt extract (ME), 146 mM sucrose, 0.8% (w/v) agar and 13.3 µM benzyl amino purine (BAP). Survival, callus type and colour, degree of callus formation, time of callus formation and total fresh weight of callus varied among the treatments. All untreated explants (controls) survived and produced friable EC in the 2nd or 3rd week of culture, whereas the irradiated nucelli showed delayed response. EC derived from the nucelli irradiated at 10, 20 and 40 Gy appeared in the 3rd week of culture, whereas EC from the 60 and 80 Gy doses appeared in the 4th week. Exposure to higher doses (100 and 120 Gy) completely suppressed callus formation. After 35 days of culture, an average of 697 and 660 mg of EC were harvested from the nucelli irradiated at 10 and 20 Gy, respectively, which was higher than those at 40 Gy (441 mg), 60 Gy (436 mg) and 80 Gy (380 mg). EC were initiated and proliferated and subsequently regenerated into plantlets. DNA of plantlets from the 20, 40 and 60 Gy exposure were individually amplified and compared to the control for early detection of mutagenesis using retrotransposon, inter simple sequence repeat and markers related to seedlessness. No variants were observed from the plantlets produced.
Stevia rebaudiana Bertoni is a perennial herb that belongs to the family of Asteraceae. It is a
natural sweetener plant known as sweet leaf, which is estimated to be 300 times sweeter than cane
sugar. In this study, micropropagation and in vitro mutagenesis of this natural herb was
successfully conducted. It was found that shoot tips on MS medium supplemented with 1 mg/l
Kinetin showed the highest shoot induction and multiplication after 3 weeks of culture
(5.50±1.95a). Radiosensitivity test was conducted to identify the dose that killed 50% of the
irradiated explants (LD50) for in vitro stevia shoots and to select effective doses to be used for the in
vitro mutagenesis. Shoot tips were irradiated with acute and chronic gamma radiation at 0, 10, 20,
30, 40, 60, and 80Gy. At 60 Gy and 80 Gy, all treated shoot tips were not survived. In this study,
LD50 for the stevia was estimated at 29 Gy for acute irradiation and 45 Gy for chronic irradiation.
The effective doses were selected at 10, 20, 30 and 40 Gy. These selected doses were applied for the
in vitro mutagenesis of the stevia shoots
The fermentation of Pleurotus pulmonarius (non-irradiated) and Pleurotus pulmonarius (irradiated) were carried out in Erlenmeyer flask 500 mL (working volume 250 mL) and screened for the presence of β-glucan (1, 3:1, 6). The biomass obtained was extracted using Modified Mizuno Method to get the endopolysaccharide. The endopolysaccharides of Pleurotus pulmonarius (irradiated) contained higher content of β-glucan (1, 3:1, 6) with 16.7 g/100g crude polysaccharide compared to the non-irradiated strain. The irradiated strain was chosen for further investigation. Fractionation of endopolysaccharide Pleurotus pulmonarius (irradiated) using column chromatograph yielded 7 fractions. The first fraction (F1) contained high molecular weight fraction ~ 105 Da which potential immunomodulation characteristics. The Pleurotus pulmonarius (irradiated) was produced in a 5 L air-lift bioreactor. The highest biomass was obtained at air flowrate of 2 L/min, yielding productivity of 2.56 g/L.d.