Wheat Genotype(s) with Genetic Tolerance to the Soilborne Pathogens Rhizoctonia solani, Rhizoctonia oryzae, Pythium ultimum, and Pythium irregulare

Abstract

The invention is a new genotype of wheat with tolerance to the root pathogens Rhizoctonia solani, Rhizoctonia oryzae, Pythium ultimum, and Pythium irregulare group IV.  This genotype was originally generated by screening mutagenized seed of the spring wheat for increased tolerance to Rhizoctonia solani.  Later experiments determined that tolerance is due to a transmissible semi-dominant, single gene trait.  This wheat genotype represents the first case of genetic tolerance to the Rhizoctonia root rot in wheat. 

Rhizoctonia root rot is an important yield-limiting disease in direct-seeded wheat production in the US Pacific Northwest, Canada, and Australia.  Under severe disease pressure, plants are stunted, and seedlings are killed, creating uneven stands and bare patches in the field, which severely reduces grain yields and grain quality.  No fungicide capable of controlling this pathogen is available.  Currently, Rhizoctonia is managed through crop rotation, tillage, or by using glyphosate (Roundup) to eliminate infected plants from the previous crop year (green bridge).  As Rhizoctonia and Pythium exhibit broad host ranges, rotation is less effective compared to other pathogens.  These practices increase reduced profitability, increase the risk of soil loss due to erosion, and increase risk of developing glyphosate tolerant weed populations due to excessive application.  The commercial release of a Rhizoctonia tolerant wheat variety could increase acceptance of reduced tillage/direct-seeded farming systems, thereby decreasing soil erosion, reducing production costs, and increasing profitability.

Applications and Advantages

Offers effective and cost-saving measure to effectively control soilborne pathogens, thereby increasing crop yield and profitability.

IP Status

US and PCT applications pending                 

Publication

PCT publication WO 2007092907