Extensive Genetic Diversity is Present within North American Switchgrass Germplasm

Area of Science:

• Plant Genetics
• Bioinformatics
• Ecology

Background:

• Switchgrass (Panicum virgatum) exists in upland and lowland ecotypes across North America.
• Prior genetic studies primarily focused on northern switchgrass, necessitating broader genetic diversity analysis.

Purpose of the Study:

• To expand the understanding of genetic diversity in a wider range of North American switchgrass, particularly lowland ecotypes.
• To identify ecotype-specific and population-specific single nucleotide polymorphisms (SNPs) for germplasm evaluation.

Main Methods:

• Exome capture sequencing data were generated for 632 lowland switchgrass individuals.
• Analysis of over 37 million single nucleotide polymorphisms (SNPs) from 1169 individuals across 140 populations.
• Population structure and genetic diversity analyses were performed using high-confidence SNPs.

Main Results:

• Seven distinct population groups were identified with moderate genetic differentiation between lowland and upland ecotypes (Fst = 0.06).
• High nucleotide diversity (0.0135) was observed across all switchgrass individuals, attributed to outcrossing and polyploidy.
• Ecotype-specific and population-specific SNPs were identified.

Conclusions:

• Glaciation events, ploidy, and flowering time differences contribute to distinct gene pools in switchgrass across ecotypes and regions.
• The identified genetic resources support trait association for forage, restoration, and biofuel feedstock development.
• This study provides a valuable genetic resource for future switchgrass improvement efforts.