For both isolation and culture of the microspores, a filter sterilized
Nitsch and Nitsch (1967) medium, as modified by Lichter (1981) and
by Takahata and Keller (1991) with 9% sucrose (NLN-9), at pH 5.8 was
used. After heat treatment for seven days, the swollen anthers were
chosen, mixed with NLN-9 medium and immediately extrusion
with glass rod to isolate microspores. Microspores suspension was
obtained by filtration through 150 μm nylon screens. This suspension was centrifuged 3 times at 500 rpm for 5 min and resuspended in NLN-
9 medium. The microspore density was adjusted to 8 × 104–10 × 104
per ml. Isolated microspores were cultured in 60 mm Petri dishes containing
2 ml microspore suspension.
The cultures were incubated at 28 °C with 80% air humidity and
maintained in the dark for three weeks, and then transferred to a gyratory
shaker agitating at 60 rpm in darkness at 28 °C.