50 PNL Volume 17 1985 RESEARCH REPORTS
Loennig, W. E. Institute of Genetics
University of Bonn, Federal Republic of Germany
As described previously (3), streptomycin blocks chlorophyll-syn-
thesis in pea. A similar effect was found in pea seedlings when the
seeds were treated with chloramphenicol, but treatment with the antibio-
tics nitrofurazon and neomycinsulphate produced no such effect.
With respect to the streptomycin treatment, 87 families (altogether
1424 plants) of the prospective M2 were investigated. No chlorophyll
mutants were detected among these plants. Two out of 87 families
yielded no plants at all. The mother plant of one of these two had pro-
duced only six seeds, all of which were smaller than those of DGV and
were of greenish color (instead of the normal yellow of DGV); none
germinated. For the second case no special features were noticed. A
weak mutagenicity of streptomycin would be in agreement with the
findings of Manna and Karmakar (2), but in disagreement with other
authors (see review by Suter and Jaeger [4]). The present results seem
still too scanty to decide the question, but if streptomycin is a muta-
genic agent it does not seem to be very potent. Normally the production
of different chlorophyll mutations is the first indication of a potent
mutagen in plants.
Chloramphenicol proved to be mutagenic in several bacterial tests,
but non-mutagenic in others (see [4]). As a pilot test, 200 seeds were
treated with chloramphenicol (100 seeds in 0.25% and 100 in 0.50%
chloramphenicol solution for 14 hours). Only six seeds germinated of
the group treated with the 0.5% solution and 19 of the other; two from
the latter group showed white spots in the lower leaves and lower parts
of the stems in the M1. The resulting 25 M2 families consisted of 653
plants. One of these M2 families (with 40 plants in all [M1 treated
with 0.25% chloramphenicol-solution]) showed a mutant with relatively
large white sectors in the leaves in the upper part of the plant.
Inasmuch as our mutant collection contains no mutants resembling this
phenotype and inasmuch as no 3:1 segregation took place in the M2, a
cross fertilization can be excluded. The M3 corroborated the conclu-
Most of the descendents of the mutant plant showed the same fea-
tures as the mother plant. Moreover, several families were descended
from the family in which the new mutant first appeared. The mother
plants had not shown the mutant character, but in some M3 families the
new mutant segregated, demonstrating that the mutation event had actual-
ly taken place in the M1 plant. I want to provisionally suggest the
symbol 1ws (large white spots) for this mutant.
So the pilot test with this small sample of only 25 families has
already produced at. least one mutant (another possible mutant affecting
internode length has not yet been proved). To verify the mutagenic
potential of chloramphenicol and its mutation spectrum in pea, a large
scale study is needed. As there have been several reports that chloram-
phenicol is also very dangerous in man (1), mutation tests with higher
plants may corroborate the bacterial test results concerning the "posi-
tive" mutagenic potential of chloramphenicol.
1. Langbein, et. al. (eds.). 1983. 'Bittere Pillen', pp. 368-
369. Kiepenheuer & Witsch, Cologne.
2. Manna, G. K., and M. Karmaker. 1979. The Nucleus 22:96-103,
3. Loennig, W.-E. PNL 15:36-37.
4. Suter, W. and I. Jaeger. 1982. Mutation Res. 97:1-18.
PNL Volume 17 1985
Fig. 1. M3: Descendants of chlorophyll mutant which appeared
after treatment with chloramphenicol.