In Vitro Mutagenesis and Propagation of Paulownia Tomentosa (Thumb) for Salt Tolerance

Abstract

The study aimed to refine a protocol for micropropagation and to develop the plant's ability to withstand salinity by the use of physical and chemical mutations, so that it can be cultivated in new lands that are not suitable for other crops. Shoot tips and stem segments of Paulownia tomentosa were firstly sterilized and cultured on different media types containing benzyl amino purine (BAP) at 0, 0.1, 0.25, 0.5, and 1.0 mg/l to choose the best combination for explant growth and proliferation. To examine the plant's ability to withstand salinity, Paulownia tomentosa shoots were first irradiated with the doses of gamma rays at 0.0, 30, 60, 90, 120, and 150 Gray (Gy) and secondly, cultured on a WPM medium containing sodium azide "NaN3" at 0.0, 0.1, 0.2, 0.4, 0.8. and 1.0 mM for 5 min. Both irradiated and NaN3-treated shoots were cultured on different levels of NaCl. Inter Simple Sequence Repeats (ISSR) technique was used to detect variations caused by gamma rays and NaN3. Results showed that at 120 Gy of gamma-ray, one fragment with primer UBC824 vanished and one fragment with primer 17898B at 150 Gy appeared. In comparison, one fragment with primer either UBC873 or UBC867 at 1.0 mM and 0.8 mM of NaN3, respectively, can be considered a positive marker of Paulownia salt tolerance. Treated shoots gave the greatest number of roots/shoot (6.0) on WPM half strength with NAA at 2.0 mg/l. Increasing gamma doses or NaN3 concentrations decreased survival rate. Variation created by mutation provides the raw material for natural selection and is a driving force in evolution.