PNL Volume 13 1981
RESEARCH REPORTS
7
TWO NEW DOUBLE MUTANTS OF PISUM
Gottschalk, W. Institute of Genetics, Bonn, Federal Republic of Germany
After X-irradiation of dry seeds, mutant 38E was selected in an M family.
The plants are very long. They begin to flower under field conditions
about one week earlier than the initial line due to the formation of the first
flowers at very low nodes. In this respect, mutant 38E corresponds with the
early flowering and ripening mutant 46A of our collection homozygous for gene
efr as was borne out in the F1's between the two genotypes. In F2, all the
plants were early flowering, confirming the F1 findings. The following segre-
gation for stem length was obtained:
- 88 plants like 38E
- 29 plants like 46A
(expectation for 3:1=87.75:29.25).
Thus, mutant 38E is a double mutant homozygous for efr and a gene for
very long internodes, with two genes having mutated more or less simultaneously
in the same initial cell during irradiation. The neutron-induced mutant 2590A
of our collection, like 38E, proved to be a double mutant for the same two
genes. Furthermore, it was shown that the early flowering mutant 45C, obtained
after X-irradiation, is identical with mutant 46A, both being homozygous for
efr.
Thus, gene efr has mutated four times in our X-ray and neutron trials.
In mutants 45C and 46A, only efr mutated, whereas efr and a gene for long
internodes mutated in the embryos giving rise to mutants 38E and 2590A.
Long-stemmed pea mutants often show a markedly increased seed production
as compared to the control values of the initial line or of other mutants
with shorter internodes. This is to some extent also the case in mutant 38E.
Its seed production was compared over 5 successive generations with the
corresponding values of mutant 46A (Table 1).
Thus, the gene for long internodes improves the selection value of gene efr
if we take the seed production of the two genotypes as parameter.
