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...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.展开更多
From the progenies of a telotrisomic of chromosome 9 short arm of an indica rice variety, Zhongxian 3037, a phenotypical variant was selected. The variant plant had rolled leaves, dispersed plant type, as well as a lo...From the progenies of a telotrisomic of chromosome 9 short arm of an indica rice variety, Zhongxian 3037, a phenotypical variant was selected. The variant plant had rolled leaves, dispersed plant type, as well as a low seed-setting rate. Cytological and molecular cytological investigations revealed two extra chromosomes, which were the shortest in somatic cells of the variant. Fluorescent in situ hybridization （FISH） analysis using a rice centromere specific DNA （RCS2） and a DNA sequence specific for chromosome 9 on premetaphase and pachytene chromosomes showed that these two chromosomes were the short arms of chromosome 9. That is to say, the variant was a telotetrasomic of chromosome 9. Among the 25 pachytene cells, the two telosomic chromosomes paired each other to form a bivalent and didn＇t pair with other normal chromosome 9 as multivalents in 96% cells. However, the bivalent was easy to disassociate in advance.展开更多
基金funded by the Startup Foundation from Nantong University (03083074)partially supported by the National Natural Science Foundation of China (31771862)+1 种基金Special Funds for Technology Innovation of Fujian Agriculture and Forestry University(KFA20001A)the Research Program of Guangxi Key Laboratory for Sugarcane Biology (GXKLSCB-20190203)。
文摘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.
基金supported by the National Natural Science Foundation of China (Grant No. 30600345, No. 30770131 and No. 30771210).
文摘From the progenies of a telotrisomic of chromosome 9 short arm of an indica rice variety, Zhongxian 3037, a phenotypical variant was selected. The variant plant had rolled leaves, dispersed plant type, as well as a low seed-setting rate. Cytological and molecular cytological investigations revealed two extra chromosomes, which were the shortest in somatic cells of the variant. Fluorescent in situ hybridization （FISH） analysis using a rice centromere specific DNA （RCS2） and a DNA sequence specific for chromosome 9 on premetaphase and pachytene chromosomes showed that these two chromosomes were the short arms of chromosome 9. That is to say, the variant was a telotetrasomic of chromosome 9. Among the 25 pachytene cells, the two telosomic chromosomes paired each other to form a bivalent and didn＇t pair with other normal chromosome 9 as multivalents in 96% cells. However, the bivalent was easy to disassociate in advance.
