RFLP-based assay of Sorghum bicolor (L.) Moench genetic diversity

Area of Science:

• Plant Genetics
• Molecular Biology
• Agricultural Science

Background:

• Sorghum (Sorghum bicolor) exhibits significant morphological diversity within its cultivated (bicolor) and wild (verticilliflorum) subspecies.
• Understanding the genetic diversity and relationships between these subspecies is crucial for crop improvement and conservation.

Purpose of the Study:

• To compare the nuclear DNA diversity between cultivated and wild sorghum subspecies using restriction fragment length polymorphism (RFLP) analysis.
• To investigate the phylogenetic relationships and gene flow mechanisms between sorghum subspecies.

Main Methods:

• Sixty-two single-copy DNA clones were used to analyze RFLP patterns in 53 sorghum accessions from Africa, Asia, and the United States.
• Phylogenetic analysis using parsimony and population statistics were employed to assess genetic diversity and differentiation.

Main Results:

• Greater nuclear diversity was observed in the wild subspecies (verticilliflorum) compared to the cultivated subspecies (bicolor).
• Phylogenetic analysis revealed distinct clusters for the subspecies, with some intermediate accessions.
• Morphological races generally grouped together based on RFLP similarities, though exceptions were noted, particularly in the bicolor race.

Conclusions:

• Outcrossing appears to be a more significant driver of gene flow between wild and cultivated sorghum than seed dispersal.
• Morphological classification may not always align with genetic similarity, potentially due to selection for specific traits like forage quality.
• Low but significant heterozygosity was detected, indicating limited genetic differentiation between the subspecies.