S.M. Rozov, F.L. Gorel and V.A. Berdnikov.

Institute of Cytology and Genetics, Novosibirsk, 630090, RUSSIA

In the M2 progeny of the EMS-treated SG line a mutant SGE-0264 was found. This mutant is characterised by the presence of large bracts on the inflorescence, an open flower with a non-joint keel and sometimes with the sepals form a widened bract-ring-like structure. The upper surface of SGE-0264 leaflets is glossy due to the lack of wax. The lower leaflets surface, stipulae, stem and pods of this mutant have a normal wax coverage.

Previously Gottschalk (1) described his mutant line carrying a recessive allele of the brac gene forming large bracts and causing the appearence of an open flowers in pea. The chromosome location of gene brac was not determined. We crossed SGE-0264 mutant with the line WL-6115, carrying the original Gottschalk's brac. The F1 hybrid plants possessed large bracts and flowers of open type. If our newly obtained brac mutant behaves as recessive trait, the results of this test evidenced that our brac mutant and Gottschalk's brac are allelic to each other. SGE-0264 line was crossed with testerline WL-1238. The F1 progeny of this cross did not carry any bract structures, so we can suggest that SGE-0264 brac mutant is of a recessive nature and can be named by the same Gottschalk's genesymbol - brac.

While studying the segregation in F2 progeny of cross GSE-0264 it was found, that the presence of bracts and absence of wax layer on the upper surface of leaflets, characteristic for parent SGE-0264 phenotype, are not absolutely linked to each other - in F2 population both plants with wax / without bracts and without wax/with bracts were found. So, we can suggest that the effect of wax coverage is produced by another, distinct from brac, mutant gene in line SGE-0264. SGE-0264 was crossed with line WL-1255, carrying the gene wlo, which causes exactly the same wax coverage disturbances as our mutant gene. The F1 plants were of normal wax-type, so this genes are non-allelic. In such case we propose to name the newly obtained in line SGE-0264 wax mutant gene as wlo-2. The results of segregation analysis of genes brac, wlo-2 and d after the cross SGE-0264 x WL-1238 are shown in table 1.

The data presented in this table is an obvious evidence for all the three studied genes are linked to each other and locate in d-segment of the pea linkage map in the following order:

Now we have no sufficient evidence for the proper location of d-segment on the pea linkage map. Some years ago it was excluded from the linkage group I, recently some arguments were obtained for this chromosome segment to belong to the linkage group VI (2). We hope that in the subsequent studies, which now are in progress, the use of this new convenient markers, brac and wlo-2, located far enough from gene d, will soon help in solving this problem.

This work was partially supported by the Russian State Program for Fundamental Research.

References:

1. Gottschalk W., 1961, Planta, v.57, p.313-330.

2. Temnykh S.V., Gorel F.L., Berdnikov V.A. Weeden N.F.,1995 Pisum Genetics, v.27, p.23-25.