ARS | Publication request: Rhizoctonia Resistant Wheat -- Potential New Resources for Control for Soilborne Pathogens.

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: May 20, 2009
Publication Date: N/A

Technical Abstract: Pacific Northwest (PNW) wheat, barley, legume and canola varieties are susceptible to the broad host-range soilborne pathogens that cause Rhizoctonia root rot and Pythium root rot. Effective control of these diseases will likely require additional approaches and resources. We have identified promising new sources of genetic resistance against Rhizoctonia solani AG-8 and R. oryzae, Pythium ultimum and P. irregulare group I. These four pathogens are among the most damaging to PNW dryland cereal production systems. Until the generation of the Rhizoctonia-resistant wheat genotype Scarlet-Rz1 by mutagenesis, non-GMO resistance to root diseases has been elusive. The resistance in Scarlet-Rz1 is readily deployable by wheat breeders, making it unique. In greenhouse trials, Scarlet-Rz1 seedlings are resistant to about ten-fold more pathogen than is detected in symptomatic field soils. Field trials are being planned to determine how seedling resistance impacts field traits, such as heading date and yield. Chromosome 4 from the wild grass Thinopyrum confers resistance to eyespot, an important disease of winter wheat caused by the soilborne pathogen Tapesia yallunde, when introduced into hexaploid wheat Chinese Spring. We have determined that seedlings of Chinese Spring carrying Thinopyrum chromosome 4 also are resistant to R. solani AG-8 and P. ultimum. Scarlet-Rz1, Chinese Spring-chromosome 4 addition lines and other genotypes of wheat under development offer novel genetic resources for combating Rhizoctonia and Pythium in the PNW.