Horizontal resistance

In genetics, the term horizontal resistance was first used by J. E. Vanderplank^[1] to describe many-gene resistance, which is sometimes also called generalized resistance.^[2] This contrasts with the term vertical resistance which was used to describe single-gene resistance. Raoul A. Robinson^[3] further refined the definition of horizontal resistance. Unlike vertical resistance and parasitic ability, horizontal resistance and horizontal parasitic ability are entirely independent of each other in genetic terms.^{[citation needed]}

Successive rounds of breeding for horizontal resistance proceed in a more traditional fashion, selecting plants for disease resistance as measured by yield. These plants are exposed to native regional pathogens, and given minimal assistance in fighting them.^[4]