A Mendelian breeding technique designed to transfer a single gene, usually a resistance gene, from a wild plant into a cultivar. The cultivar and the wild plant are cross-pollinated to produce a hybrid progeny. A hybrid individual that carries the resistance gene is then back-crossed with the cultivar parent to produce a second breeding cycle. This process of back-crossing is repeated for several breeding cycles until the hybrid is indistinguishable from the cultivar parent, except that it carries the resistance gene from the wild parent. Note that back-crossing is an excellent technique when breeding for vertical resistance, but that it dilutes polygenically inherited characters, and it should not be used when breeding for horizontal resistance. See also: Pedigree breeding. Bacteriocide
A pesticide that kills bacteria. Bacteriophage
A bacterium (pl. bacteria) is the most primitive of the cellular organisms. About 1,600 species of bacteria are known to science and some of these are parasitic on plants. Bacteria are prokaryotes. That is, although their cells do contain DNA, they do not contain a nucleus.
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