38 PNL Volume 16 1984

RESEARCH REPORTS

CROSS FERTILIZATION IN PEAS UNDER DIFFERENT ECOLOGICAL CONDITIONS

Loennig, W.-E. Institute of Genetics, University of Bonn

Federal Republic of Germany

A simple method to determine the frequency of cross fertilizations

occurring in cultivated peas recently was described (1). The work has

been continued with WL 6040 which has green cotyledons (gene i) and is

linearly fasciated. Table 1 shows ten and Table 2 eleven control groups

of this line on two ecologically different fields (locations I and II).

Location II has a richer insect fauna than location 1. The control

groups were distributed among 20,000 plants with the dominant allele

(gene I, yellow cotyledons) on location I and about 7,000 plants with

this allele on location II.

The tables show that nearly one third of all plants bear one or

more cross fertilizations. In comparison with the data from location 1

( = 100%), the number of seeds arising from cross pollinations was 59.13%

higher on location II (non-rounded numbers as basis). Unexpectedly, the

percentage of contaminated plants was only slightly higher on location

II (+ 1.29%). I have not yet found a satisfactory explanation for this.

PNL VoLume 16 1984

RESEARCH REPORTS

Table 2. Percent cross fertilizations on location II.

The percentage of cross fertilizations in the ten most severely

contaminated plants is given in Table 3.

Table 3. Percent cross fertilizations of the 10 most severely

contaminated plants.

To make sure whether the seeds of the stated cross fertilizations had

really been correctly determined, 54 plants grown from such yellow

seeds were investigated. Of these, 51 plants segregated for yellow and

green cotyledons; the other three plants which did not show segregation

produced 9, 10, and 37 yellow seeds respectively. For the first two a

deficit of the recessives may be the explanation; for the last plant the

problem is open. Nevertheless, all seeds had been correctly determined

as yellow.

40 PNL Volume 16 1984

RESEARCH REPORTS

Special marker genes of the plants growing around the control groups

(for example, for the structure and color of the seed coats of ecotype

arvense and the fasciated type line WL 6) were identified in the F2

proving that cross-po1lination was the cause for the yellow seeds.

Bombus agrorum Fabricius and Bombus terrestris L. were the most likely

candidates for the pollen transfer (Figs. 1 and 2).

1. Loennig, W.-E. 1983. PNL 15:40.

Fig. 1. Bombus agrorum in younger Fig. 2. B. agrorum on older

pea-blossom. blossom.

(Original colored photos converted to black and white.)