Tiss~~e C~~ltl~res
Acer saccl~arutn tissue culture derived from root was
obtained from James Marvin of the University of Vermont
and was grown in suspension culture in the dark
at 25°C on a Linsmaier and Skoog medium (6) containing
2 mg/litre indoleacetic acid (IAA) and 0.2 mg/litre kinetin
(referred to as Acer medium). Haplopappus gracilis
tissue cultures were derived from seeds and were grown
in suspension culture in light at 30°C on a modified
Eriksson's medium (3) with 1 mg/litre naphthaleneacetic
acid (NAA) 20 pg/litre kinetin. Petunia suspension cultures
were grown at 30°C in the light in Nagata and
Takebe medium (1 1) with 3% sucrose and without
mannitol.
The Acer culture contains few large clumps of cells
but consists mainly of elongated cells in chains of two
to six cells. Log-stage and late-log-stage cultures were
used directly for experiments without sizing. For experiments
with Haploppapl~s, cultures were first filtered
through Nitex mesh screens (505, 202, 120 microns (p);
Tobler, Ernst, and Traber, Inc.) to remove large cell
clumps. Single cells and small clumps of two to eight
cells were collected on a 53-p pore-size mesh.