PNL Volume 15

1983

RESEARCH REPORTS

PRELIMINARY NOTE ON ORANGE COTYLEDONS: A NEW COTYLEDON COLOR

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.