Rozov, S.M., Gorel, F.L.                                                              Institute of Cytology and Genetics
and Berdnikov, V.A.                                                                     Novosibirsk 630090, Russia

Mutant SGE-0264 was found in the M2 progeny of the EMS-treated SG line. This mutant is characterised by the presence of large bracts on the inflorescence, an open flower with a non-joined keel, and wings fused basally with keel elements; sometimes the sepals form a widened, bract-like ring structure. The upper surface of SGE-0264 leaflets is glossy due to the lack of wax. The stipules, stem, pods and lower surface of the leaflets have a normal wax coverage. Following crosses with other lines, it became clear that SGE-0264 is a double mutant and the two traits ‘presence of bracts’ and ‘absence of wax on the upper surface of leaflets’ are the result of recessive mutations at two different loci (e.g. Table 1).

Previously, Gottschalk (1) described his mutant pea line carrying a recessive allele of the brac gene. The brac plants are characterised by large bracts on the inflorescence and flowers with an open appearance. The chromosomal location of the brac gene was not determined. We crossed mutant SGE-0264 with line WL-6115, which carries Gottschalk’s original brac mutation. The F1 hybrid plants possessed large bracts and flowers of an open type. Thus our bract mutant and Gottschalk’s brac are allelic. We suggest WL-6115 as type line for mutant allele brac-1 and SGE-0264 as type line for mutant allele brac-2.

The mutation in SGE-0264 that causes loss of wax from the upper surface of the leaflets results in a phenotype the same as, or at least very similar to, that caused by the wlo mutation. We therefore crossed SGE-0264 with line WL-1255, which carries wlo. The F1 plants had normal wax, so the two mutations are in different genes. We propose to name the second gene wlo2, with line SGE-0264 as the type line for mutant allele wlo2-1.

Line SGE-0264 was crossed with multiple marker line WL-1238. The dihybrid segregation data for brac, wlo2 and marker d are given in Table 1. The data indicate that all three genes are in linkage group IB in the sequence d…28…brac…36…wlo2. With only one established marker (d) involved, it remains to be shown on which side of d the new genes are located. The identity of linkage group IB is not yet wholly resolved as eight linkage groups are shown in the 1996 pea map (3). Temnykh et al. (2) have presented arguments that the d segment may belong to linkage group VI. We hope that studies now in progress using these new convenient markers, brac and wlo2, will help in solving this problem.

Table 1. Joint segregation data in the F2 of cross SGE-0264 (brac, wlo2) x WL-1238 (d).

¹ A, a first locus; B, b second locus. ***P < 0.0001.

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

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