Related Experiment Videos
Genome evolution in the genus Sorghum (Poaceae)
H James Price1, Sally L Dillon, George Hodnett
1Department of Soil and Crop Sciences, Texas Agricultural Experiment Station, Texas A&M University, College Station, TX 77843-2474, USA. hj-price@tamu.edu
Annals of Botany
|December 15, 2004
Summary
Sorghum genome size varies significantly, with perennials having larger DNA content than annuals. Phylogenetic analysis reveals distinct lineages with differing genome sizes, challenging previous theories on grass genome evolution.
Area of Science:
- Plant evolutionary biology
- Genomics
- Phylogenetics
Background:
- The role of DNA content variation in plant evolution and adaptation is poorly understood.
- Investigating genome size and chromosome number in Sorghum offers insights into evolutionary processes.
Purpose of the Study:
- To determine chromosome number and 2C DNA content for 21 Sorghum species.
- To analyze these variations within a phylogenetic framework to understand plant evolution and adaptation.
Main Methods:
- Flow cytometry was used to measure 2C DNA content.
- A Sorghum phylogeny was constructed using combined nuclear ITS and chloroplast ndhF DNA sequences.
Main Results:
- Chromosome counts ranged from 2n = 10 to 40, with new numbers reported for two species.
- 2C DNA content varied 8.1-fold across species, with significant differences between annual and perennial species.
- Perennial Sorghum species exhibited significantly larger mean 2C DNA content and genome size compared to annual species, particularly in Australian populations.
Conclusions:
- Phylogenetic analysis revealed two main Sorghum lineages: one with 2n = 10 species and large genomes, and another with 2n = 20, 40 species and smaller genomes.
- Evidence suggests a phylogenetic reduction in genome size within the 2n = 10 lineage.
- Genome size evolution in Sorghum appears more complex than a simple increase, contradicting the 'genomic obesity' hypothesis in grasses.