Assessing genetic diversity and population structure in a citrus germplasm collection utilizing simple sequence...

Area of Science:

• * Plant genetics and genomics
• * Molecular markers and population genetics

Background:

• * Understanding citrus genetic diversity is crucial for breeding and conservation.
• * Citrus taxonomy is complex due to extensive hybridization.

Purpose of the Study:

• * To assess molecular polymorphism and genetic diversity in a large citrus germplasm collection.
• * To elucidate phylogenetic relationships and population structure within the Citrus genus.
• * To test the hypothesis of limited natural citrus species and extensive hybridization.

Main Methods:

• * Utilized 24 simple sequence repeat (SSR) markers to analyze 370 Citrus accessions.
• * Calculated genetic diversity statistics and constructed neighbor-joining trees for phylogenetic analysis.
• * Employed a model-based clustering approach for probabilistic population assignment.

Main Results:

• * Detected 275 alleles with an average of 11.5 alleles per locus and high polymorphism information content.
• * Phylogenetic analysis indicated Fortunella clustering within Citrus and Poncirus as a sister genus.
• * Identified five distinct populations, supporting a model of limited natural species and extensive hybridization.

Conclusions:

• * The study confirms significant genetic diversity within the analyzed citrus germplasm.
• * Phylogenetic and population structure analyses support a core of few natural Citrus species.
• * Most existing citrus varieties are products of hybridization between these ancestral forms.