I have used the CTAB extraction method (with Lithium chloride) for RNA extraction from coconut leaves

CTAB method (Mosr et al 2004, Jakola et al 2001)

1. 1 g sample + 10 mL CTAB (65°C) in 50 mL corning tube. Incubate at 65 °C, 30 min, Votex, every few minutes.

2. Equal volume Chloroform, R.T., 10 min, vortex often.

3. Centrifuge, 5000 rpm, 5 min.

4. Transfer supernatant to new tube (4 mL). Add ¼ Volume of 10 M LiCl (2.5 M final concentration). 4 °C, overnight (on ice).

5. Centrifuge, 15000 g, 20 min, 4 °C.

6. Wash the pellet with 2 M LiCl.

7. Resuspend pellet in 500 µl 10 mM Tris HCl pH 7.5 ice 10 min.

8. Add 1/10 Vol 2 M potassium acetate pH 5.5 ice 10 min.

9. Centrifuge 13000 rpm for 10 min.

10. Collect supernatant, add 0.9 Volume of isoproponol (or 2.5 volume of ethanol), -20 °C,1 h or -70 °C, 30 min.

11. Centrifuge, max speed.

12. Wash with 70 to 80% ethanol.

13. Air dry pellet.

14. Resuspend RNA in 50 to 100 µL nuclease free water.

However, the final product contained a high amount of DNA (Figure 01), By DNase treatment can’t remove all amounts of DNA in the RNA sample.