Worldwide pattern of multilocus structure in barley determined by discrete log-linear multivariate analyses

Area of Science:

• Population Genetics
• Molecular Ecology
• Plant Breeding

Background:

• Understanding the genetic structure of cultivated barley (Hordeum vulgare L.) is crucial for crop improvement and evolutionary studies.
• Previous research has hinted at geographic variations in barley's genetic makeup, but comprehensive multilocus analyses were lacking.

Purpose of the Study:

• To analyze the multilocus genetic structure of 1,032 cultivated barley accessions.
• To investigate hierarchical organization within barley's genetic system across different loci and chromosomes.
• To determine how geographic origin influences barley's multilocus genetic structure.

Main Methods:

• Electrophoretic assay of seven enzyme loci from 1,032 cultivated barley accessions.
• Application of discrete log-linear multivariate techniques to analyze multilocus structure.
• Model construction involved identifying and eliminating inconsequential terms, building a descriptive log-linear model, and evaluating association terms.

Main Results:

• The multilocus genetic system of cultivated barley is organized into hierarchically structured complexes of loci, extending across different chromosomes.
• Significant differences in multilocus structure were observed across various geographical regions.
• Barley from Southwest Asia, the center of origin, shows intermediate structure. Genetic divergence increases with distance from this center, with West Europe, East Asia, and Ethiopia exhibiting maximal differences.

Conclusions:

• Cultivated barley possesses a complex, hierarchically organized multilocus genetic system.
• Geographic origin is a major determinant of barley's multilocus genetic structure, with clear divergence patterns radiating from the center of origin.
• These findings have implications for understanding barley evolution, domestication, and developing targeted breeding strategies.