Monday, February 28, 2011

Cherokee Tiger Project

The Cherokee Tiger Project began by crossing a heritage tomato called Cherokee Purple with a tiger striped dwarf tomato variety. The project is a group effort between tomato growing friends to select, expand and perpetuate the tastiest and most interesting looking sister lines that evolve from growing out subsequent generations of the original cross.

To create the original cross, I emasculated a blossom on a Cherokee Purple tomato vine, and applied pollen from a dwarf tomato variety which has unusually pale green, rugose foliage, and bears yellow fleshed, grape shaped saladette tomatoes with darker yellow tiger stripes in the skin. Cherokee Purple is a large, dense fleshed, sweet, beefsteak tomato with deep red flesh, and possessing the gf (green flesh) gene that causes a retention of chlorophyll in the fully ripened tomatoes, resulting in a brownish or maroon undertone that makes the tomato appear "purple" rather than pink.

The dwarf gene from the tiger striped parent is recessive, so in the F1 hybrid generation, all the plants express the indeterminate, long vine characteristic of the Cherokee Purple parent. In addition to being dwarf, the tiger striped parent also is determinate and chartreuse foliaged, both results of recessive genes, so the F1 hybrid plants all appear the same with realtively tall vines and smallish, deep red, globe shaped tomatoes the result of the dominant genes masking the recessive genes in fully heterozygotous pairings.

But when the F2 vines emerge, they display the segregating genes recombined in all sorts of unusual and interesting expressions. One quarter of the F2 plants will be determinate, 1/4 will be dwarf, 1/4 will have the chartreuse foliage, 1/4 will have yellow flesh instead of blood red, and so on with regard to all the recessive traits. However, not all the dwarf plants will possess all the other recessive traits, and conversely many of the fully indeterminate long vine plants will express one or more of the recessive traits. Additionally, since the gs (green stripe) gene that causes the skin striping is sort of "intermediately" recessive, it appears faint on the skin of the F1 tomatoes, but fully expresses on the fruit of 1/4 or more of the F2 plants.

To display the wide variability expected in the F2 Cherokee Tiger plants, one tray of 16 randomly planted seeds sprouted the last week of January 2011, now have grown into 16 seedlings with no two looking the same on this the last day of February! One is a 1-inch tall "micro dwarf" seedling, two are obviously fully dwarfed 2.5-inch rugose seedlings with one being dark green and the other chartreuse, and there are 13 others of various heights up to 7 inches tall with a variety of leaf shapes, leaf textures, and various degrees of green tint. By comparison, every F1 hybrid plant last year was identical, as should be the case with first generation, fully heterozygoteous hybrids.

This blog will track the progress of the Cherokee Tiger Project. Stay tuned.


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