Characterization of meiotic chromosome behavior in the autopolyploid Saccharum spontaneum reveals preferential chromosome pairing without distinct DNA sequence variation

• Published in: Crop Journal
• Main Authors: Xin Zhang, Zhuang Meng, Jinlei Han, Haris Khurshid, Ayman Esh, Robert Hasterok, Kai Wang
• Format: Article
• Language: English
• Published: KeAi Communications Co., Ltd. 2023-10-01
• Subjects: Autopolyploidy; Saccharum spontaneum; Meiosis I; Chromosome behavior; Chromosome pairing
• Online Access: http://www.sciencedirect.com/science/article/pii/S2214514123000296

Autopolyploidy and allopolyploidy may represent an evolutionary advantage and are more common in plants than assumed. However, less attention has been paid to autopolyploidy than to allopolyploidy, and its evolutionary consequences are largely unclear, especially for plants with high ploidy levels. In this study, we developed oligonucleotide (oligo)-based chromosome painting probes to identify individual chromosomes in S. spontaneum. Using fluorescence in situ hybridization (FISH), we investigated chromosome behavior during pachytene, metaphase, anaphase, and telophase of meiosis I (MI) in autotetraploid, autooctoploid, and autodecaploid S. spontaneum clones. All autopolyploid clones showed stable diploidized chromosome behavior; so that homologous chromosomes formed almost exclusively bivalents during MI. Two copies of homologous chromosome 8 with similar sizes in the autotetraploid clone showed preferential pairing with each other with respect to the other copies. However, sequence variation analysis showed no apparent differences among homologs of chromosome 8 and all other chromosomes. We suggest that either the stable diploidized pairing or the preferential pairing between homologous copies of chromosome 8 in the studied autopolyploid sugarcane are accounted for by unknown mechanisms other than DNA sequence similarity. Our results reveal evolutionary consequences of stable meiotic behavior in autopolyploid plants.