The document discusses the Vertifolia effect and boom-bust cycle in plant breeding. The Vertifolia effect refers to the loss of horizontal resistance that occurs during breeding for vertical resistance in the presence of fungicides/insecticides. An example is the loss of horizontal resistance to potato blight after the discovery of fungicides. The boom-bust cycle describes how a resistant cultivar with a single resistance gene is widely adopted by farmers, but then virulent pathogens spread and break the resistance, leading farmers to abandon the cultivar. Maintaining horizontal resistance and incorporating resistance genes later in breeding can help reduce these effects.

1. Vertifolia Effect and Boom & Bust Cycle
in Plant Breeding
SUBMITTED TO
Dr. G. R. Lanvanya
Associate Professor
Seminar Incharge
Genetics & Plant Breeding
SUBMITTED BY
Muppala Tanuja
Credit Seminar
Semester- IV

2. J. E. Van der Plank (1963)
 Coined the term Vertifolia effect.
 Father of Epidemiology.
 Founder of horizontal and
vertical resistance

3. Definition Of Vertifolia Effect
The process of neglecting and losing
horizontal resistance in the causes of
breeding for vertical resistance will be
called as Vertifolia effect.

4. Definition Of Vertifolia Effect
The 'vertifolia effect' is a loss of horizontal
resistance that occurs when the plant
breeding is conducted either in the
presence of a functioning vertical
resistance, or under the protection of a
fungicide or insecticide.

5.  Vertifolia effect derived from the German
potato variety ‘Vertifolia’ having the late
blight resistance genes R3 and R4.
 Vertifolia effect refers to an epidemic
development in a variety carrying vertical
resistance genes and a low level of HR,
leading to heavy economic losses.

6. An Example of Vertifolia Effect
 The prime example of the vertifolia effect is the
loss of horizontal resistance to Potato blight
(Phytophthora infestans).

7.  The loss of horizontal resistance to potato blight
began soon after the discovery of the first
fungicide, called Bordeaux mixture, in 1882.
This fungicide made the breeding much easier
because, so many seedlings were no longer being
killed by blight.

8. NOTE -
 Every host has horizontal resistance to all
it’s parasites but the level of horizontal
resistance is low in most modern cultivars
due to the Vertifolia effect.

9. Implications of Vertifolia Effect on
Plant Breeding
 Breeding of disease resistant crops.
Opting to cross in ‘R’ genes at the end of
the breeding cycle to maintain levels of
horizontal resistance.
Enhancing horizontal resistance to avoid
potential catastrophic crop losses.

10. Boom & Bust Cycle
 Proposed by Pristley (1970).
In a boom-and-bust cycle, a resistant
cultivar with single, major resistance gene
is introduced into an agro ecosystem to
control a plant disease.

11. Boom and Bust cycle in
Plant Breeding
Figure (2.1)

12. Boom & Bust Cycle
 If the resistant cultivar has good agronomic
characters and is widely accepted by farmers
because of it’s disease-resistant character, the
cultivar spreads and is planted over a large area.
 This is the "boom" part of the cycle.
Boom & Bust Cycle

13. Boom & Bust Cycle
 The virulent pathotypes spread and infect all fields
with the resistant cultivar, causing an epidemic and
leading to a loss of effectiveness of the resistance
gene.
 Because the resistance is "broken", farmers stop
planting the resistant cultivar and the
corresponding resistance gene decreases in
frequency.
 This is the "bust" part of the cycle.
Boom & Bust Cycle

14. Boom and Bust cycle in
Plant Breeding
Figure (2.1)

15. Figure (2.2)

16. Boom & Bust Cycle
 It is characterized by an increase in the area
planted to the resistance gene (Figure 2.2).
 Selection imposed by the resistant cultivar
increases the frequency of pathogen strains with
the virulence mutation, usually in a time-lagged
manner that shadows the increase in frequency of
the resistance gene (Figure 2.2).
Boom & Bust Cycle

17. Boom and Bust Cycle

19. References
 Vanderplank, J.E. (1963) Plant Diseases: Epidemics and Control.
Academic Press, New York and London, 194-195pp.
 Brown, J.K.M.; Rant, J.C. (2016). "Fitness costs and trade‐offs of
disease resistance and their consequences for breeding arable
crops". Plant Pathology. British Society for Plant
Pathology. 62 (51): 83–95.
 Grunwald, Niklaus; Cadena Hinojosa, Mateo (2002). "Potato
cultivars from the mexican national program: Sources and
durability of resistnace against late blight". Phytopathology. The
American Phytopathological Society. 92 (7):
688. doi:10.1094/phyto.2002.92.7.688.