PNL Volume 15
Blixt, S.
Weibullsholm Plant Breeding Institute
Landskrona, Sweden
Plant Experiment Station, Wiatrowo, Poland
Swiecicki, W. K.
Yellow and green cotyledon color, due to dominance and recessivity
in I, respectively, have been known since the time of Mendel. During
routine determinations of the probable genotypes of accessions held in
the gene bank at Wiatrowo, a line was found with seeds of a clearly dif-
ferent color. This line, obtained from the Chinese Academy of
Agricultural Sciences under the name "Ren-shou da bai Wan dou", was
designated as AO 113 by the donor. It was assigned number WT 11145 in
the Wiatrowo catalogue. The seed color of the whole seed with seed coat
(genotype a.) seemed to be pink, but the cotyledons had more of an orange
hue after the seed coat was removed. Because the character was clearly
different from the typical expression of gene I the line was immediately
crossed with WT 3527. Later we found that the original sample actually
contained two types, which we here designate as brick and orange.
Interpretation of the F2 segregation presented difficulties from the
outset. Despite seemingly clear color differences, it was impossible to
establish any regular segregations in orange and yellow observed on
whole seeds, i.e., seeds with seed coat. After removing the seed coat
from all the F2 seeds, the cotyledons showed a range of hues from yellow
to orange. The whole population could be divided into five classes:
yellow, dark-yellow, light-orange, orange, and brick-red. Though the
differences betweeen neighboring classes were slight, the classes were
more or less discrete with little overlapping (Table 1). An interpreta-
tion in terms of segregation ratios is not possible because the color of
the individual parent plants of Wt 11145 was not ascertained before
crossing and we now know that Wt 11145 contains two types. It can only
be stated that the segregation non-yellow to yellow is normal 3:1. The
character behaves as a cotyledon character, i.e., segregating within the
plant as does I or R.
Very recently F^ seeds from three new crosses were obtained
(Table 2). These results seem to indicate that brick and orange
cotyledon colors may be alleles of I perhaps also showing intermediate
inheritance, which would be interesting, as semidominance is not common
in Pisum. It is also possible at this stage that the different hues are
due to modifying effects of other color genes.
A closer look in wiatrowo' scollection showed some more accessions
with the orange cotyledons (e.g., Wt 4401). A first screening of the
Weibullsholm collection up to now resulted in at least two different
hues of yellow. There is also a very slight indication that "bleaching"
might be involved.
We will continue this analysis of cotyledon colors but wanted to
publish these preliminary results with the hope it will encourage
coleagues to screen their material for possible deviations from ordinary
yellow and green. Whatever the results, we would very much appreciate
being informed of the outcome and receiving small samples of any such
deviating material.
10 PNL Volume 15 1983