Subgenome Discrimination in Brassica and Raphanus Allopolyploids Using Microsatellites

Area of Science:

• Plant genetics
• Cytogenetics
• Molecular biology

Background:

• Intergeneric crosses between Brassica species and Raphanus sativus create novel crops.
• Distinguishing donor genomes is vital for assessing cytogenetic stability in distant crosses.
• Microsatellite repeats are effective tools for subgenome discrimination in allopolyploids.

Purpose of the Study:

• To identify genome-specific microsatellites for discriminating Brassica (A, C, B) and Raphanus (R) genomes.
• To validate the specificity of identified microsatellites using fluorescence in situ hybridization (FISH).
• To assess the utility of these microsatellites in analyzing genetic stability of synthetic polyploids.

Main Methods:

• Exploration of microsatellite content in Brassica rapa (AA), B. oleracea (CC), B. nigra (BB), and R. sativus (RR).
• Validation of genome specificity using fluorescence in situ hybridization (FISH).
• Localization of microsatellites, including ACBR_msat20, within rDNA arrays.

Main Results:

• Three microsatellites with A, C, and B/R genome specificity were identified.
• ACBR_msat14 and ACBR_msat20 showed specificity for A and C genomes, respectively.
• ACBR_msat01 detected in both B and R genomes; no marker distinguished B from R.
• Localization of ACBR_msat20 within the 45S rDNA array in ×Brassicoraphanus 977 indicated genome rearrangement.

Conclusions:

• Identified microsatellites are valuable probes for subgenome identification in Brassica and Raphanus species.
• These markers facilitate the analysis of genetic stability in newly synthesized polyploids.
• Combined use of microsatellites, rDNA, and telomeric probes aids homologous chromosome identification.