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Unstable Allotetraploid Tobacco Genome due to Frequent Homeologous Recombination, -. Segmental Deletion, and Chromosome Loss

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Molecular Plant 2018年第7期11卷 914-927页

作者： Shumin Chen Feihong Ren Lei Zhang Yong Liu Xuejun Chen Yuanmei Li Liang Zhang Bin Zhu Pan.Zeng Zaiyun Li Robert M. Larkin Hanhui Kuang Key Laboratory of Horticultural Plant Biology Ministry of Education Key Laboratory of Horticultural Crop Biology and Genetic Improvement (Central Region) MOA College of Horticulture and Forestry Sciences Huazhong Agricultural University Wuhan 430070 People's Republic of China Yunan Academy of Tobacco Agricultural Science Kunming Yunnan Province People's Republic of China College of Plant Science Huazhong Agricultural University Wuhan 430070 People's Republic of China These authors contributed equally to this article.

The types of mutations and their corresponding frequencies are difficult to measure in complex genomes. In this study, a high-throughput method was developed to identify spontaneous loss-of-function alleles for the resistance gene N and the transgenic avirulence gene P50 in allotetraploid tobacco. A total of 2134 loss- of-function alleles of the N gene were identified after screening 14 million F1 hybrids. Analysis of these mutants revealed striking evolutionary patterns for genes in polyploids. Only 14 of the loss-of-function mutations were caused by spontaneous point mutations or indels, while the others were caused by home- ologous recombination （with a frequency of 1/12 000） or chromosome loss （1/15 000）. Loss of the chromosome with the PS0 insertion occurred at a similar frequency （1/13 000）, and the frequency of spon- taneous segmental deletion in this chromosome was 1/16 000. Both homeologous recombination and chromosome loss considerably decreased the viability of the mutants. Our data suggest that the high mutation rate in polyploids is probably due to the occurrence of homeologous recombination and the toler- ance of large mutations such as chromosome loss in polyploid genomes. Frequent mutations tend to drive polyploids to extinction unless a novel mutation helps the polyploid to effectively compete with diploids or find a new ecological niche.

关键词： polyploid genome evolution homeologous recombination chromosome loss spontaneous mutation

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New mechanism of partial duplication and deletion of chromosome 8:A case report

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World Journal of Clinical Cases 2021年第24期9卷 7139-7145页

作者： Yan Jiang Shuang Tang Fang He Jue-Xin Yuan Zhu Zhang Office of Prenatal Diagnosis Mianyang People’s HospitalMianyang 621000Sichuan ProvinceChina Department of Obstetrics Mianyang People’s HospitalMianyang 621000Sichuan ProvinceChina Office of Prenatal Diagnosis West China Second University HospitalSichuan UniversityChengdu 610000Sichuan ProvinceChina

BACKGROUND During meiosis,the recombination of homologous chromosomes produces some new heritable mutations,which are the basis of biological evolution and ***,when there is pericentric inversion of chromosomes,unbalanced gametes will be formed in the process of germ cell *** SUMMARY A 23-year-old pregnant woman at 25 wk of gestation wanted to terminate her pregnancy due to fetal chromosomal *** had no exposure to toxic or hazardous substances before and during pregnancy,no history of medication usage during pregnancy,and she underwent cystectomy of ovarian cysts in *** the second day of the 16th week of gestation,non-invasive prenatal testing showed chromosome 8 copy number *** genetic counseling,her pregnancy was *** Recombinant offspring chromosome is rarely seen when the inversion segment is shorter than one-third of the chromosome *** terms of the mechanism of chromosome 8 duplication/deletion occurrence,attention should be paid to the production of unbalanced gametes by the pairing of homologous chromosome during meiosis,and the possibility of mitotic recombination exchange as well.

关键词： Chromosome 8 spontaneous mutation Mitosis Non-invasive prenatal testing Case report

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