What is race specific resistance?
Race-specific resistance is characterized by the presence of differential genetic interactions between host and pathogen genotypes. It implies the possibility to identify races. Non-race-specific resistance is characterized by the absence of genetic interactions between host and pathogen genotypes.
What is specific resistance in plants?
Apart from physical barriers, plants have two major types of defense against potential pathogens. In ‘race-specific’ resistance, plants match single mendelian resistance genes with the ‘avirulence’ genes possessed by races of a pathogen.
Why horizontal resistance is durable?
Horizontal resistance theoretically provides a fairly stable resistance in preventing epidemics of plant diseases. Because the resistance is not absolute, it does not exert an extreme selection pressure on the pathogen population for the evolution of new races.
How is horizontal resistance used?
Horizontal resistance is polygenic, and acts against all races of blight. Vertical resistance, conferred by the R-genes, is oligogenic, and can be overcome by a change of race. Horizontal resistance slows down the rate at which disease increases in the field.
What is gene for gene concept?
One is a plant gene called the resistance (R) gene. The other is a parasite gene called the avirulence (Avr) gene. Plants producing a specific R gene product are resistant towards a pathogen that produces the corresponding Avr gene product.
What is qualitative resistance?
Qualitative resistance results in phenotypes that fit into distinct categories according to Mendelian ratios. Genetic mapping of qualitative resistance results in a single genetic locus that often maps to genes encoding RLK or NLR proteins.
What is non host resistance?
Nonhost resistance is a broad-spectrum plant defense that provides immunity to all members of a plant species against all isolates of a microorganism that is pathogenic to other plant species.
Which is considered as durable resistance?
Durable disease resistance is defined as resistance that has remained effective while a cultivar possessing it has been widely cultivated in an environment favoring the disease. Durable resistance is often achieved against diseases that show little or no specialisation into races pathogenic to particular cultivars.
What is durable resistance a general outline?
Summary. Resistance to pathogens may be durable for several reasons. iv) Resistance genes themselves are durable; the pathogen cannot adapt to these genes at least not within short time spans. The genetically durable resistance is often of a quantitative nature.
Who introduced the vertical and horizontal resistance?
In genetics, the term horizontal resistance was first used by J.E. Vanderplank to describe many-gene resistance, which is sometimes also called generalized resistance. This contrasts with the term vertical resistance which was used to describe single-gene resistance. Raoul A.
What are R proteins?
The R protein guards another protein that detects degradation by an Avr gene (see Guard Hypothesis). The R protein may detect a Pathogen-Associated Molecular Pattern or PAMP (alternatively called MAMP for microbe-associated molecular pattern). The R protein encodes enzyme that degrades a toxin produced by a pathogen.
What is modern gene concept?
A. A segment of DNA capable of crossing over. It encodes the synthesis of a gene product either RNA or protein. During a gene expression, the DNA is first copied into RNA and then RNA can be directly functional or be the intermediate template for a protein that performs a function.
How is vertical resistance different from race-nonspecific resistance?
In comparison to vertical resistance, race-nonspecific resistance is often controlled by several genes or quantitative trait loci (QTLs), which is partial resistance against multiple races of the pathogen.
How is a race defined in biological terms?
Race (biology) Races may be genetically distinct populations of individuals within the same species, or they may be defined in other ways, e.g. geographically, or physiologically. Genetic isolation between races is not complete, but genetic differences may have accumulated that are not (yet) sufficient to separate species.
What does microbiology have to do with antibiotic resistance?
The Microbiology Module addresses the intricate science behind the antibiotic resistance phenomenon. It will explain what takes place within the bacterial cell to enable antimicrobial resistance and how it can be detected and measured.
Which is an example of a biological arms race?
Commercial Cucumis melo (cantaloupe and muskmelon) production, for example, has been engaged in a biological “arms race”, since 1925, against cucurbit powdery mildew, caused by successively arising races of Podosphaera xanthii fungus, with new cultivars of melons being developed for resistance to these pathogens.