Genetic resistance in plants refers to heritable traits that suppress pathogen development. It is controlled by one or more nuclear or cytoplasmic genes. Most plants are resistant to most diseases through non-host resistance. Resistance is more common than susceptibility. Genetic resistance can be categorized as horizontal/general resistance, effective against all pathogen races, or vertical/race-specific resistance, effective against only some races. Horizontal resistance involves polygenic, quantitative traits and allows some pathogen reproduction but not epidemic growth, while vertical resistance is often controlled by single major genes and provides complete resistance or susceptibility depending on pathogen virulence.

2.  Genetic resistance refers to those heritable features of a host plant
that suppress or retard development of a pathogen.
 It is controlled genetically by the presence of one, a few or many
genes for resistance in the plant i.e., either nuclear or cytoplasmic or
both in nature.
 Most plants are resistant to most diseases(Non-host resistance).o
Resistance is the rule and susceptibility is an exception.
 Disease resistance is a relative trait in plants rather than
anabsolute quality.

3.  These terms were coined by the late J. E. Van der plank (“Plant
Diseases: Epidemics and Control” 1963), who was possibly the
most important plant pathologist who ever lived.
 The terms are derived from his classic diagrams that define the
two kinds of host resistance.

4.  According to J.E.van der plank (1963) when the resistance is evenly
spread against all races ofpathogen it is called "horizontal" or
"lateral" resistance.
 All plants have a certain, but not always the same level of possibly
unspecific resistance that is effective against each of their pathogen.
 Such resistance is sometimes called partial, race non specific,
general, quantitative, polygenic,adult-plant, field, additive, durable,
stable, non-differential Rate-reducing, minor gene,incomplete or
multigenic resistance.
 In the case of horizontal resistance, reproduction rate of pathogen is
never zero, but it is less than one, ie., r>0 but<1.

5.  Breeding for horizontal resistance is cumulative: A good cultivar is
replaced only with a better cultivar.
 HR is present universally in wild and domesticated plants and
operates against all races of a pathogen, including the most
pathogenic ones.
 Horizontal resistance can be domesticated just as yield and quality
have already been domesticated.
 An inadequate level of horizontal resistance can be increased by
further breeding

7.  According to Van der plank(1963) vertical resistance is that kind of
resistance in plant varieties that effective against some races of
pathogen and not against others.
 Such resistance differentiates clearly between races of pathogen, as it is
effective against specific races of pathogen and ineffective against
others.
 It is also known as race-specific, major gene, strong, qualitative,
monogenic or oligogenic, hypersensitive resistance, R-gene resistance,
racial resistance, pathotype specific resistance, unstable resistance and
differential resistance.
 Pathotype-specificity denotes that the host carrying a gene for vertical
resistance is attacked by only that pathotypes, which is virulent toward
that resistance gene; to all other pathotypes the host will be resistant.