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Biotechnological Studies for Improving of Stevia (Stevia rebaudiana Bertoni) in vitro Plantlets

2013; Volume: 14; Issue: 1 Linguagem: Inglês

1990-9233

Sabah Hassanen, Rasha Khalil,

Plant Genetic and Mutation Studies

Stevia rebaudiana Bertoni is an economically important medicinal plant act as a sugar substitute for diabetic and obese people. In the present investigation, an efficient protocol for rapid in vitro propagation of stevia and reduction of the large number of lost plantlets during acclimatization. Murashige and Skoog (MS) medium supplemented with 2.0 mg/l N6-benzyl amino purine (BAP) recorded the maximum number of shoots of 43.9 shoots/explant, but these shoots were very thin, containing many lateral shoots, but with low survival percentage during acclimatization. Hundred % of rooted plantlets were recorded on MS medium with 0.5 and 1.0 mg/l indole 3- butyric acid (IBA). Pre acclimatization treatments using growth retardants; alar (B9; succinic acid2-2-dimethylhydrazide) and cycocel (CCC; chloroethyltrimethyl ammonium chloride) in culture medium were applied to study their effect for improving root system and post acclimatization of rooted plantlets. The highest number of roots (7.3 roots/shoot), root length (2.64 cm) and plant height (4.29 cm) were obtained on MS medium supplemented with 1.0 mg/l IBA and 0.5 mg/l Alar. Stevia rebaudiana Bertoni plantlets were acclimatized and grown well in planting medium containing sand, peatmoss and vermiculite, at equal volumes. The best recorded survival percentage in greenhouse was 93.3%. Analysis of SDS-PAGE of soluble protein and eleven isozymes systems revealed complete similarity (100%) among the three samples of stevia (mother plant, plants treated with growth retardant and non treated plants). The level of polymorphism detected among the three samples of stevia was 44.70% using randomly amplified polymorphic DNA (RAPD), 24.00% using inter simple sequence repeat (ISSR) and 22.03% using amplified fragment length polymorphisms (AFLP). With an average of 30.24% polymorphism between the three samples obtained by all used biochemical and molecular markers. From previous results, it is clear that growth retardants increased the survival percentage in acclimatization under greenhouse conditions and, this protocol could be useful in producing a true-to type plants and for the use of Stevia rabodiana medicinally and commercially Bertoni.