What is an avirulence gene?

What is an avirulence gene?

Avirulence (avr) genes are defined as genes of the pathogen that govern its specific recognition by particular plant genotypes. Recognition depends upon the presence of a pair of matching genes, an avr gene in the pathogen and a resistance (R) gene in the plant.

What is avirulence factor?

Virulence factors are the molecules produced by pathogens that help them to invade the host and hence cause disease. From: Brenner’s Encyclopedia of Genetics (Second Edition), 2013.

What is HRP gene?

Abstract. hrp genes control the ability of phytopathogenic bacteria to cause disease and to elicit hypersensitive reactions on resistant plants.

What do AVR genes encode?

Avirulence (Avr) genes interact in a gene-for-gene relation with resistance genes. Viral Avr genes encode for coat proteins, replicase or movement proteins. (Hammond-Kosack KE, Jones JD.

What is a resistance gene?

Resistance genes (R-Genes) are genes in plant genomes that convey plant disease resistance against pathogens by producing R proteins. The main class of R-genes consist of a nucleotide binding domain (NB) and a leucine rich repeat (LRR) domain(s) and are often referred to as (NB-LRR) R-genes or NLRs.

What are Elicitors in botany?

Elicitors in plant biology are extrinsic or foreign molecules often associated with plant pests, diseases or synergistic organisms. This response results in the enhanced synthesis of metabolites which reduce damage and increase resistance to pest, disease or environmental stress.

Are Adhesins virulence factors?

Adhesins are virulence factors that allow bacteria to attach to host cells. Although many pathogenic bacteria express various kinds of adhesins, often they are encoded on the bacterial backbone DNA (such as S fimbriae and Type 1 fimbriae expressed by E.

Why is LPS a virulence factor?

As a surface structure, LPS interacts with the host; host defense systems recognize a bacterium by the elicited immune responses to its LPS. Therefore, the LPS is an immunoreac- tive surface antigen. The LPS is therefore an important factor in the pathogenicity of infec- tions due to gram-negative bacteria.

Why pathogens have avirulence genes?

Avirulence genes are originally defined by their negative impact on the ability of a pathogen to infect their host plant. Many avirulence genes are now known to represent a subset of virulence factors involved in the mediation of the host-pathogen interaction.

What is the role of AVR gene in pathogenesis?

Avr genes have dual functions: Pathogens containing Avr genes are avirulent to plants carrying the matching R genes, while they are virulent in race, strain, pathovar or species-specific way to plants without carrying the matching R genes.

What is an example of genetic resistance?

For example, specific resistance genes against Puccinia graminis tritici incorporated into new wheat varieties frequently become obsolete within a few years due to the emergence of new races of the pathogen.

What is a resistance determinant?

Resistance determinant: A catch-all term that includes both resistance genes and resistance mutations that give a microbe the ability to resist the effects of one or more drugs. Resistance gene: A gene that gives microbes the ability to resist the effects of one or more drugs.