ry, a modifier gene for red color in yellow tomato fruits.
G1458 tomato (PI 125831 from Afghanistan) in 4 generations bore green fruits that turned yellow but remained firm during a few days. Finally, these fruits became soft-ripe and red, orange or yellow, or combinations of these colors over parts or all of the surface area. The cuticle was yellow and often attached to red cells in the rind to a depth of 1 to 5 mm. The central flesh remained pale yellow except for occasional red streaks or masses of red flesh. Different fruits on the same plants sometimes varied much in the amounts of red and orange colors. However, some of the yellow-fruit plants had more red color in their-fruits than occurred in the fruits of other plants. Associated characters were large plants with hairy stems, non-wilty leaflets, smooth peel and dark green tops on the unripe fruits. The fruits were 3 to 6 cm. in diameter; small fruits were globular but most of the large fruits were oblate, lobed, fasciated and catfaced.
G1458 was crossed with Marglobe (for G1734) and with Rutgers (G1735, G1736, G1738 and G1739) as female parents. The first generation of plants from these crosses bore only red fruits, showing the dominance of the r^+ allele. The F2 generation was represented by 245 plants from 11 selections.
They segregated as follows:
________________________________________________________________ No. plants with Total ________________________________________ number Red Yellow fruits containing Cross of plants fruits red and orange colors ________________________________________________________________ G1734 105 75 30 G1735 34 26 8 G1736 29 24 5 Gl738 38 32 6 G1739 39 31 8 Total 245 188 57 ________________________________________________________________The segregations deviate a little from a 3:1 ratio maybe due to inaccuracy in calculations based on small numbers or because the red-color modifier makes the segregation complex.
The development of red color in yellow tomato fruits apparently is due to a recessive gene. The symbol, ry, is proposed for a modifier-gene that causes the development of red color in yellov tomato fruits of G1458 and Golden Sphere. It appears to be a modifier of the r-allele for yellow flesh color. A similar "Pink color in yellow fruit" was described in Texas Agr. Exp. Station Bul. 698. 1947. The ry-allele may darken red flesh color when associated with the R-allele.
More evidence will be needed to prove that ry is distinct from r.