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Abstract. Sunaryo W, Widoretno W, Nurhasanah, Sudarsono. 2016. Drought tolerance selection of soybean lines generated from somatic embryogenesis using osmotic stress simulation of poly-ethylene glycol (PEG). Nusantara Bioscience 8: 45-54. Somaclonal variation is an alternative source to create genetic variability including generating a novel character like drought tolerance. The objective of this research was to select the drought tolerant lines derived from somatic embryogenesis (somaclones) of 4 soybean genotypes using drought stress simulated by Polyethylene Glycol (PEG). Soybean seeds (R 1 generation) generated from 37 somaclones (R 0 generation) were grown on semi hydroponic system using Greenleaf as supporting medium. The seedlings were watered with half strength of liquid Murishage and Skoog nutrient. The PEG solution treatment of either 0% or 15% (PEG: w/v = -0.41 Mpa osmotic potential) was applied in the MS solution, from the seedlings of 14 days old until harvesting period. The vegetative growth, intensity of leaf firing, plant biomass, and drought sensitivity index variables were observed during the PEG application. The same procedure was applied to the seeds, propagated conventionally, from the same genotypes as controls. The results showed that somatic embryogenesis had altered the drought sensitivity of soybean genotypes under drought stress simulated by PEG. Interestingly, the different drought tolerance level was showed by the R 1 plants. Some lines were increased and the other lines were decreased compared to the control genotypes. From a total of 185 R 1 plants, 4 plants increased their tolerance against drought stress and grouped as tolerant genotype.

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When obtaining plantlets, embryo maturation and simultaneous germination are important steps in plant micropropagation via somatic embryogenesis. Several studies have shown that the use of carbohydrates as a carbon source plays a significant role in inducing somatic embryo development in certain plant species. This study aimed to establish a somatic embryo maturation protocol for Batu 55 Mandarin (C. reticulata Blanco.) by examining the effect of various types of sugar and concentrations. The results showed that the type and concentration of sugar added to the medium affect the somatic embryo maturation of Batu 55 Mandarin. Galactose and maltose enhance somatic embryo maturation more effectively than does sorbitol. The combination of galactose or maltose with sorbitol was able to improve somatic embryo maturation more effectively than galactose or maltose alone. The combination of galactose and sorbitol enhanced the maturation of somatic embryos more effectively than did change the concentrations of maltose or sorbitol. It can be concluded that sugar type and concentration had effects on citrus somatic embryo development. The combination of sorbitol (36.5 mM) with galactose 73 mM was able to augment citrus somatic embryo maturation more effectively than the other concentrations applied.

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