THE INFLUENCE OF MALE STERILITY ON OUTCROSSING IN PEAS

62 PNL Volume 16 1984

RESEARCH REPORTS

Myers, J. R. and E. T. Gritton

Department of Agronomy

University of Wisconsin, Madison, WI USA

Because the pea has a cletstogaraous flower, the frequency of out-

crossing is low in most northern environments (1, 3). Thus, methods of

enhancing hybridization may be of interest to the breeder. We obtained

several pea lines segregating for male sterility and have characterized

them genetically and cytologically (2). Working in the field with F2

segregates of marker line-male sterile crosses, we observed pod set on

ms plants (Table 1). The percentage of ms plants with at least one pod

varied considerably among ms genes. Crosses between different marker

lines to the same male sterile exhibited similar pod set behavior.

However, plant height affected the amount of pod set with short plants

(le le) showing a lower percentage pod set than tall plants (Le/-).

Short plants of ms-2 and ms-6 exhibited lower percentage pod set, while

ms-7 had the highest percentage of both tall and dwarf plants. Seed

from the open pollinated pods were grown to determine floral phenotype.

It was expected that fertile progeny were the result of outcrossing

while most ms progeny were due to selfing. However, as much as

one-third of the progeny could be male sterile due to outcrossing in a

closed, randomly mating F_ population. Because these ms lines were

grown in the nursery among many other pea lines, the percentage of ms

progeny due to outcrossing would be somewhat less than one-third. As

shown in Table 2, ms-2, ms-5, and ms-6 exhibited 25.2% or fewer male

sterile progeny, suggesting that these genes confer a high degree of

male sterility. All other male steriles showed 43.2% or greater ms

progeny which indicates varying amounts of fertility restoration.

Bumblebees appeared to be the primary insect vector and were ob-

served gathering both pollen and nectar from older flowers. In

particular ms-2, ms-5, and ms-6 may have some value In facilitating

recombination where large amounts of crossed seed are required.

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

Myers, J. R., and E. T. Gritton. 1984. PNL 16:60-61.

White, 0. 1917. Proc. Am. Phil. Soc. 56:487-588.