Allelic interactions defining Raphanus raphanistrum AHAS resistance level: strong vs weak target-site AHAS resistance...

Area of Science:

• Plant genetics
• Herbicide resistance mechanisms
• Molecular biology

Background:

• Investigated chlorsulfuron resistance and genetic dominance in Raphanus raphanistrum.
• Utilized genotypes with target-site resistance mutations (Ala-122-Tyr, Asp-376-Glu) in the AHAS gene.

Purpose of the Study:

• To evaluate chlorsulfuron resistance and genetic dominance in Raphanus raphanistrum.
• To compare the efficacy of different AHAS target-site resistance mutations.

Main Methods:

• Assessed acetohydroxyacid synthase (AHAS) enzyme activity and I50 values.
• Determined whole-plant survival rates and median lethal doses (LD50) under varying chlorsulfuron concentrations.
• Evaluated aboveground growth reduction using GR50 values.

Main Results:

• The Ala-122-Tyr allele conferred significantly higher resistance (higher I50, LD50, and GR50 values) compared to the Asp-376-Glu allele.
• Homozygous and heterozygous genotypes with the 122-Tyr allele showed greater survival and reduced growth inhibition.
• The 122-Tyr allele demonstrated dominance over the 376-Glu allele.

Conclusions:

• The Ala-122-Tyr mutation represents a stronger target-site resistance allele in R. raphanistrum compared to the 376-Glu allele.
• Results enhance understanding of AHAS target-site resistance evolution in weeds.