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

 Marx (1) identified a new gene py (precocious yellowing) and reported linkage between py and the group V marker gp with a distance of 22 cM. In order to map the position of the py locus, we crossed line WL2134 (py) with our tester-line RT-9, which carries eight markers for linkage group V. Dihybrid F₂ segregation data from this cross are shown in Table 1. The data show py is located between det and gp and generate the map shown opposite for the det to gp segment of group V.

Table 1. Joint segregation data in the F₂ population of cross RT-9 ґ WL2134 (py).

^{1 A/a, first gene; B/b, second gene; h, heterozygous. When both genes are dominant, the capital letter stands for the dominant allele. When the second gene is codominant, the capital A stands for the dominant allele of the first gene and capital B for an allele of the second gene in coupling with A. When both genes are codominant, the capital letter stands for an allele of the first parent.}

^{*,**,*** P < 0.01, 0.001, and 0.0001, respectively.}

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

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 1. Marx, G.A. 1971. Pisum Newsletter 3:20.