A GRAY-GREEN FOLIAGE MUTANT, POSSIBLY WELLENSIEK'S "lead"
Marx, G. A. New York State Agricultural Experiment Station, Geneva, NY U.S.A.
Among four mutants reported by Prof. Wellensiek in 1971, one was designated
as "lead" (PNL 3:46). The term "lead" was not used as a symbol but as a
short description of the phenotye, viz. gray-green foliage. An attempt to
procure the mutant from Prof. Wellensiek was unsuccessful because somehow
the seed got lost after Prof. Wellensiek retired but before he had sent it
to other workers. We therefore became resigned to putting this potentially
useful mutant in the extinct category.
However, in the summer of 1977 I noted that plants of PI 244109, grown
by the Northeast Regional Plant Introduction Station (Geneva, NY) that year,
had a distinctive gray-green foliage color, thus raising the possibility
that the accession carries the "lead" mutant. This PI accession originated
in The Netherlands and represents a cultivar named 'Ceres'. Seed of PI 244109
was sent to Prof. Wellensiek for an opinion on whether or not the plants
appeared to be identical with plants of his original mutant "lead". He
concluded (personal communication) that the PI line indeed appeared to be
phenotypleally identical with "lead", with "a probability approaching cer-
tainty". Hereafter in this discussion "lead" is also used to designate the
phenotype of the mutant in PI 244109.
PI 244109 was crossed with a number of stock lines in my collection.
The F1's from these crosses had the normal phenotype and the F2 populations
gave good monogenic segregation ratios (Table 1). Moreover, 13 of 19 pro-
genies from single, normal F2 plants segregated for "lead" whereas 6 pro-
genies remained constant for the normal, non-mutant phenotype. The 13
segregating progenies showed good agreement with the expected 3 normal :
1 "lead" ratio (Table 2). Since Wellensiek had found linkage between "lead"
and fa on chromosome 4 (CrO=25%), we looked for a linkage of the mutant in
our material with chromosome 4 markers. We found no clearcut evidence of
linkage between "lead" and Le, fa, or was. The population sizes were not,
however, sufficiently large to conclude that the mutant in PI 244109 either does
or does not show the same linkage relations as Wellensiek found for his
"lead" mutant. New experiments will have to be initiated to settle the
matter. The determination of linkage relationships for "lead" would be
desirable because if it is linked with fa it would be a welcome and much
needed marker for that region of chromosome 4. But, regardless of where it
is located, it will serve as a very good seedling marker.
The basis for the phenotype is not known. The gray-green or bluish-
green foliage color somewhat resembles the phenotype of Arg but is easily
distinguished from it because Arg plants have a silvery cast; besides,
Arg is a dominant mutant whereas "lead" is recessive. There is also some
similarity between "lead" and wex, but plants of the former show no evidence
of weakness whereas the latter typically are weak and unproductive.
Since we can never really be certain if the gene found in the variety
Ceres is the same as Wellensiek's "lead", we don't know if we have a new mutant
or the resurrection of an old mutant. This poses a problem of assigning
a symbol. Provisionally, I shall suggest the symbol led for the mutant present
in the variety Ceres.
