RHIZOCTONIA TOLERANCE IN SCARLETRZ1

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RHIZOCTONIA TOLERANCE IN SCARLET-RZ1
Pat Okubara
WSU Extension Weed and Rhizoctonia Management
Workshop Spangle, WA February 19, 2008
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Tolerance Targets
Rhizoctonia solani AG-8 R. oryzae grp
III Disease in the field 20 to 85 ppg Goal
4X or 300 ppg in greenhouse
Paulitz and Schroeder (2005) Plant Dis. 89
767-772
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Previous Searches for Resistance Kidwell,
Smiley Paulitz
Higginbotham R et al (2004) Plant Dis 88
1027-1032. Smith JD et al (2003) Crop Sci 43
694-700. Smith JD et al (2003) Crop Sci 43
701-709.
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Chemical Mutagenesis Steber Laboratory
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Screen for Tolerant Plants Kidwell Paulitz

• Plant height
• No. of infected seminal roots
• Root length

M3 re-screen
Height Inf. Root Length
Scarlet 35.1 cm 4.3 254.2 cm S-015 6-4 34.8
cm 0 324.5 cm S028 8-3 40.4 cm 0
267.3 cm S028 10-1 41.2 cm 0 216.1 cm
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Characterize the Mutant Okubara Laboratory

• Independently confirm seedling tolerance
• -- R. solani AG-8 and R. oryzae III
• Quantify tolerance how much protection
• Determine mode of inheritance dominant vs.
  recessive
• Examine tolerance to other pathogens activity
  range

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Not like stripe rust
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Preparing the Inoculum
Maintain on solid medium
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Germinating the Seeds -- to avoid damping-off
Germinate 2-3 da
Transfer to infested soil
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Greenhouse Tolerance Assay

• Minimized cone to cone variation
• -- thorough mixing of pathogen
• -- standardized amt. of soil
• -- standardized watering
• -- uniform planting depth
• Used 8 to 24 plants per treatment
• Conducted multiple trials
• Harvest after 14 days

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Confirming Seedling Tolerance in BC1F2

• Root length

Line/Treatment
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Seedling Tolerance in BC1F3, BC2F2, BC2F3
Av. rating Scarlet 4.3 Rz1 2.3
BC2F2
BC2F3
Av. rating Scarlet 4.2 Rz1 2.2
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Seedling Tolerance in BC2F4
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Quantifying Tolerance
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Mode of Inheritance in BC2F2
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Pythium Tolerance in BC2F4
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Ritzville, WA - 2007
Scarlet-Rz1
Scarlet
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Mutagenized gene Rot1

• Heritable in 3 generations
• Confers tolerance to AG-8, R. oryzae III, P.
  ultimum
• and P. irregulare I but not Ggt (take-all)
• Segregates as dominant or co-dominant trait
• Field performance
• Rot1 in non-Scarlet background deployability
• Molecular markers deployability
• Mutations in Louise, Hollis, Macon

Current future
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Collaborators
Kim Kidwell Camille Steber Vic DeMacon Nathalie
Walter Tim Paulitz
originators
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