Effect of glycine betaine, polyvinylpyrrolidone and D-mannitol on micropropagation of Sideritis raeseri Boiss and Heldr. subsp. Raeseri.

Despite being protected, the number of plants that belong to Sideritis genus has decreased in the last years due to the urbanization of its natural habitat.  Sideritis raeseri Boiss and Heldr. subsp. raeseri known as mountain tea of Parnassus or Velouchi is a valuable genetic resource of the Greek flora because of its special characteristics, so, the development of a micropropagation protocol is crucial to its conservation and use in breeding programs. The objectives of the study were to evaluate the effects of glycine betaine (GB), polyvinylpyrrolidone (PVP-10) and D-mannitol applied in different concentrations in combination with auxins [α-naphthaleneacetic acid (NAA), indole-3-butyric acid (IBA)] on shoot proliferation and rooting of shoot-tip explants of the studied species. Better shoot proliferation results were obtained in the following two combination treatments: (1) 100 mg/l GB + 0.5 mg/l NAA (5.5 shoots/explant 2.34 cm long, 75% shoot multiplication), and (2) 2.5 g/l D-mannitol + 3 mg/l IBA (2.92 shoot/explant 83.33% shoot multiplication percentage). In relation to rooting, better results were performed only with PVP at 0.5 g/l applied simultaneously with 0.5 mg/l NAA (12 roots/rooted microcutting, 1.47 cm root length, 90% rooting). The ex vitro survival percentage of rooted microcuttings derived from all 5 experiments was ranged between 68% and 93%.