Divergence in Glyphosate Susceptibility between Steinchisma laxum Populations Involves a Pro106Ser Mutation

Area of Science:

• Agricultural Science
• Plant Science
• Weed Science

Background:

• Herbicide resistance in weeds poses a significant threat to global food security.
• Effective weed management programs rely on understanding resistance mechanisms.
• Steinchisma laxum is an economically important weed in rice cultivation.

Purpose of the Study:

• To characterize the resistance level of a glyphosate-resistant (R) Steinchisma laxum population.
• To identify the primary mechanisms conferring glyphosate resistance in this population.
• To inform future weed management strategies in Colombian rice fields.

Main Methods:

• Enzymatic activity assays of 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS).
• EPSPS gene sequencing to identify target-site mutations.
• Comparison of resistant (R) and susceptible (S) Steinchisma laxum populations.

Main Results:

• The R population exhibited 11.2-fold higher resistance to glyphosate compared to the S population.
• Non-target site resistance mechanisms were not implicated in glyphosate resistance.
• The Pro106Ser mutation in the EPSPS gene was identified as the primary resistance mechanism.

Conclusions:

• The Pro106Ser mutation confers significant glyphosate resistance in Steinchisma laxum.
• Integrated weed management, including diverse herbicide modes of action, is essential for controlling resistant populations.
• Findings are critical for sustainable rice production in Colombia.