Recent Crop-To-Weed Adaptive Introgression Has Reshaped the Genomic Composition and Geographical Structure of US...

Area of Science:

• Agricultural Science
• Genetics
• Ecology

Background:

• Weedy rice (Oryza sativa) is a major agricultural pest impacting global rice yields.
• Herbicide-resistant (HR) rice cultivars were introduced in the US South to control weedy rice.
• The adoption of HR rice and hybrid cultivars created new selective pressures for crop-weed interactions.

Purpose of the Study:

• To investigate the genomic and population genetic consequences of adaptive introgression in US weedy rice.
• To understand the role of hybridization and selection in weedy rice adaptation to herbicide resistance.

Main Methods:

• Genotyping-by-sequencing (GBS) was performed on 178 weedy rice samples from the southern US.
• Genomic data were analyzed alongside existing rice and weedy rice genome sequences.
• Population genetic analyses were used to infer recent evolutionary changes.

Main Results:

• Southern US weedy rice populations exhibited a reshaped geographical structure.
• Evidence of purging crop-derived alleles was found in some hybrid-origin weed strains.
• Widespread presence of herbicide resistance alleles was detected in both hybrid-derived and nonadmixed weedy rice samples.

Conclusions:

• Weedy rice populations are evolving and adapting through diverse genetic mechanisms in response to agricultural practices.
• Hybridization and selection for herbicide resistance are key drivers of weedy rice adaptation.
• Understanding these evolutionary dynamics is crucial for effective weed management strategies.