Backcrosses to L. esculentum

Tomato fruits

Long Description: The cultivated tomato L. esculentum makes large red fruits and carries the mi allele for susceptibility to nematode infection. The wild tomato L. peruvianum makes small green fruits and carries the Mi allele for resistance to nematodes.

When these two tomato species are hybridized and then backcrossed to L. esculentum the a new cultivated tomato line with Mi gene can be produced.

Backcross of F1 hybrid to L. esculentum illustrated as bookstacks

image modified from Peggy Lemaux http://ucbiotech.org/

Long Description: The F1 hybrid bookstack is backcrossed repeatedly to the L. esculentum parent (represented as a red bookstack). Each generation is selected for plants that contain the Mi gene from the L. peruvianum parent. After many backcrosses the progeny is represented as a red bookstack with just one white book representing the DNA from the L. peruvianum parent which contains the desired Mi allele.

Unfortunately, after many backcrosses the new tomato had the Mi gene with over 99% tomato genes, but still had hundreds of wild tomato genes in its genome

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