Initially, a rapid method for isolating of high quality DNA from
spindle leaves of coconut was developed. DNA was extracted from
approximately 1 g of fresh young leaves, collected from field grown
parental plants and crushed in liquid nitrogen. The crushed powder
was added to a tube containing 10 ml pre-heated extraction buffer
(100 mM Tris–HCl, 50 mM NaCl; pH 8.0). To the above, 1 ml of 10%
SDS and 50 l of -mercaptoethanol were added. The mixture was
incubated at 65 ◦C for 1 h with intermittent mixing. An equal volume
of chloroform:isoamyl alcohol mixture (24:1, V/V) was added
after incubation and homogenized by gentle inversion for 20 min
and centrifuged at 10,000 rpm for 20 min at 4 ◦C. The clear aqueous
phase containing the nucleic acid was transferred to a fresh tube
and 2/3rd volume ice-cold isopropanol was added to precipitate
the nucleic acids. It was kept at 4 ◦C for 30 min and DNA pool was
collected in 1.5 ml micro tubes. The pooled DNA was washed thrice
with 70% alcohol. The alcohol was discarded and DNA pellet was
air-dried completely and DNA pellet dissolved in 0.5 ml TE buffer
(10 mM Tris–HCl, pH 8.0 and 1 mM EDTA). RNase (4 l) was added
to the tube and incubated at 37 ◦C for 1 h. After RNase treatment, the
supernatant containing the DNA was extracted with equal volume
of chloroform: isoamyl alcohol (24:1) twice. The purified DNA was
precipitated by adding double the volume of ethanol. The precipitated
DNA was air-dried and dissolved in 0.75 ml TE buffer (10 mM
Tris–HCl, pH 8.0 and 1 mM EDTA).