MICROPROPAGATION AND EVALUATION OF GENETIC STABILITY OF FOXGLOVE TREE (Paulownia tomentosa)

Abstract

This research work aimed to fine-tune micropropagation of Paulownia tomentosa in addition to assessing the genetic stability of in vitro raised clones from it. Paulownia tomentosa explants were surface sterilized using clorox (commercial bleach 5.25% sodium hypochlorite) at 10, 20, 25 and 30% + 0.5 g/l mercuric chloride (HgCl2) at different duration times, i.e. 10, 15, 20 and 25 min. In the multiplication stage, shoots were transferred to MS medium at ¾ strength containing BAP and Kin each at (0, 0.5, 1, 2, and 4 mg/l). Whereas, the rooting medium was MS medium at ¾ strength with IBA and NAA treatments each at 0, 0.5, 1, 2, and 4 mg/l. Sterilized explant with 30% Clorox for 20 min recorded highest survival percentage. The treatment of Kin at 4 mg/l gave higher significant shoot length. Whereas BAP application at 2 and 4 mg/l gave highest significant value of both shoot number and leaf number. Both IBA and NAA at 0.5 or 1 mg/l gave highest significant root number/shoot. Whereas, auxin at 4 mg/l gave highest significant root lengths. Young plantlets resulted from in vitro were acclimitized successfully in a mixture of peat moss: perlit (2: 1) by volume that showed 85.93% survival. The genetic stability of in vitro raised Paulownia tomentosa clones was assessed by using intersimple sequence repeats (ISSRs) markers. All of the three ISSR primers screened, produced clear, reproducible and scorable bands.

The molecular size of Polymerase Chain reaction (PCR) products generated 22 fragments by these ISSR ranged from ≈460 to18660 bp. All banding profiles from micropropagated plants were monomorphic and similar to those of the mother plant, indicating 100% similarity. This confirmed the true to type nature of the in vitro raised clones.