Evening star., 1938-10-08
OF STARS,
MEN AND ATOMS
Notebook of Science Progress
in Field, Laboratory
and Study.
Bv THOMAS R. HENRY.

Plants never before known on eartn,
some of which may have great potential-
ties of adding to the food suppsy OF man
kind, now are being produced with the
aid of colchicine, a drug obtained from
the seeds and bulbs Of the autumn crocus
and long used as gout remedy.
Discovery of the potent action OF this
drug in changing the genetic constitution
of plants first was reported at the annual
exhibit of the Carnegie Institution OF
Washington last fall Since then Its po-
tentialities have been explored In many
experiment stations, especially at the New
York State Agricultural Experiment Sta
ton.
Some of the results obtained there have
been reported to the American Chemical
Society by DR.. Bernard r. Nebel. Differ
ent plant races are being developed, IN.
cluding larger fruits and more coloriul
flowers, and hitherto sterile hybrids are
being propagated The experimentation
soon will be at the stage Of commercial
application DR.. Nebel believes.
Several other drugs, 1t has been 1ouno,
have a similar effect Colchicine, how
ever, has the advantage OF acting Tor
long time within the cell without being
yery poisonous. Others tend to Kill the
cells, or do not penetrate far enough into
the cell structure to bring about any very
notable results
Said DR.. Nebel. "Plants grow by cell
division and cell enlargement. After a
cell has been laid down its potentialities
are eenetically fixed. Genes are carried
in chromosomes The number and struc-
ture of both are stable. Genes and
chromosomes have the power to repro
duce themselves previous to each cell d.
vision. This process OF reproouction anu
distribution of the mc.t vital cell units Is
well protected from the outside worlo py
a series Of barriers, including the cell
wall, the plasma membrane, the cyto-
plasm proper and the nuclear r7nembrane.
Because of the effectiveness OF these bar
riers specific chemical ceil-nuclear appn-
cations are unknown.
"Colchicine arrests cell division In the
stage at which the chromosomes have
multiplied and the halves normally would
commence to move apart. Instesd OF
sending each of two identical sister nalf-
chromosomes to distinct daughter nuclei,
these daughter chromosomes remain to-
gether and a new giant nucleus, with
twice the original chromoSome number, Is
formed The drug action gradually Is
overcome and the giant nucleus may
commence to divide normally again.
New plants. or even shoots, originate
in this way only If the initial CELL or
cells, are affected and these are usually
well protected. II the chromosome num-
ber from the original cell, or diploid. Is
doubled one obtains amphidiploid or tet-
raploid plants. If one started with
triplod with three sets one would expect
a hexaploid Genetical theory had pre-
dicted that any method OF producing
polyploids-cells having chromosome
number which is multipl: of the basic
number, would have the following results:
"Polyploid strains of given race would
be different from the originals. showing
differences in shape and physiology. .
"Polyploid strains might be crossed aod
give fertile offspring where the original
races failed.
"Polyploid branches, or shoots, OF sterile
hybrids, would be expected to be fertile.
"Polypsoid races offer more chances OF
selection than diploids
Large numbers of so-called aneuploids
cells having q chromosome number
which is not q multiple of the basic
number-with gains or losses OF few
chromosomes become available and X
ray variants can be obtained with In
creased chances of selection.
I'm the marigolds OF the African type
three generations of induced tetraploids
with increased size and greater rugged
ness were developed. Giant tetraploid
snapdragons of different varieties show
ing Increased flower size and ruggedness
of stems were produced. Tetraploid an
nual phlox were produced, and induced
tetraploid petunias with deeper flower
color and fringed flower margins.
Tomatoes readily yield chromosome
alterations. Among many forms one
type was found with pulpy fruit center
and large size. Other workers have sue
ceeded in coupling the chromosomes Of
peach, strawberry, grape and lettuce. 1t
may thus be predicted that all genera OF
plants not already having evolved high
chromosome numbers may be consider
ably changed and improved through COL
chicine. The past five years have shown
how the knowledge Of physiologic regu-
lating n1echanisms, such as plant vita
minis and hormones, lead to commercial
applications on large scale. 1t is safe
to predict that in time the system OF
generatic regulation will be accessible to
experimental treatment"
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