Difference between revisions of "Disease resistance to fungal diseases"

Revision as of 18:57, 19 February 2013

Media:Potential_Genes_of_Interest.xlsx

Background on Resistance (R) genes and avirulence (Avr) genes (Hammond-Kosack & Jones 1997)

R genes are found in the plant, while corresponding Avr gene is in the pathogen

Presumed roles of R genes:

1. help plants detect pathogenic Avr gene products
2. initiate signal transduction pathways that will help defend against the pathogen
3. "have the capacity to evolve new R gene specificities rapidly"

If the R gene or corresponding pathogenic Avr gene are not present or altered, then plant is infected with the disease

The R protein recognizes the Avr gene product (ligand), activating a signal transduction cascade that initiates the defense against the pathogen. Thus, the R gene is turned on in healthy plants. R proteins must be able to evolve quickly in order to target new pathogens specifically. The evolution of the Avr genes directly impacts the evolution of the related R gene (coevolution).

Explanation of Chitin Signaling and Fungal Invasion Response

-plants can recognize “surface-derived molecules” that elicit a general immune response (this is in addition to R gene-mediated pathways)
–pathogen-associated or microbe-associated molecular patterns (PAMPs/MAMPs)
-PAMPs are important for microbial invasion of a host cell
-glucans, chitins, and proteins derived from fungal cell walls serve as elictors, or “pathogen derived molecules” (Montesano et al 2003)
-during fungal infection, chitinases in the infected cell degrade the chitin on the cell wall of the invading fungus
-the remaining chitin fragments (chitooligosaccarides) then also serve as elicitors that provoke necessary “defense response genes”
-LysM RLKs (LsyM domain-containing receptor-like kinases): relatively large plant-specific protein family that researchers may suggest play a significant role in detecting fungal chitin

Ceasar & Ignacimuthu 2012 identified genes (mainly chitinases and glucanases) used into genetic engineering of crop plants. The tables below list important list the genes transformed and their source organism.

3 Common Blueberry Fruit Rots: ([ohioline.osu.edu/hyg-fact/3000/pdf/3213.pdf OSU])

1. Alternaria - postharvest rot; most common

Caused by Alternaria tenuissima

1. Anthracnose - serious pre- and postharvest disease

Caused by Colletotrichum acutatum (Yoshida et al. 2007)

1. Botrytis - normally minor, but can be severe

Caused by Botrytis cinerea

Things to Look Up:

abscisic acid?

KEGG Pathway - environmental information processing - signal transduction - plant hormone transduction

(look at dormancy)