Yingxin Zhang1,2, Chengming Fan3, Yuhong Chen1, Richard R-C Wang4, Xiangqi Zhang1, Fangpu Han1, Zanmin Hu5,6. 1. State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, 100101, China. 2. College of Agriculture, Yangtze University, Jingzhou, 434000, Hubei, China. 3. State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, 100101, China. cmfan@genetics.ac.cn. 4. United States Department of Agriculture, Agricultural Research Service, Forage and Range Research Laboratory, Utah State University, Logan, UT, 84322-6300, USA. 5. State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, 100101, China. zmhu@genetics.ac.cn. 6. College of Agriculture, University of Chinese Academy of Sciences, Beijing, 100049, China. zmhu@genetics.ac.cn.
Abstract
BACKGROUND: During the bread wheat speciation by polyploidization, a series of genome rearrangement and sequence recombination occurred. Simple sequence repeat (SSR) sequences, predominately located in heterochromatic regions of chromosomes, are the effective marker for tracing the genomic DNA sequence variations. However, to date the distribution dynamics of SSRs on chromosomes of bread wheat and its donors, including diploid and tetraploid Triticum urartu, Aegilops speltoides, Aegilops tauschii, Triticum turgidum ssp. dicocoides, reflecting the genome evolution events during bread wheat formation had not been comprehensively investigated. RESULTS: The genome evolution was studied by comprehensively comparing the distribution patterns of (AAC)n, (AAG)n, (AGC)n and (AG)n in bread wheat Triticum aestivum var. Chinese Spring and its progenitors T. urartu, A. speltoides, Ae. tauschii, wild tetroploid emmer wheat T. dicocoides, and cultivated emmer wheat T. dicoccum. Results indicated that there are specific distribution patterns in different chromosomes from different species for each SSRs. They provided efficient visible markers for identification of some individual chromosomes and SSR sequence evolution tracing from the diploid progenitors to hexaploid wheat. During wheat speciation, the SSR sequence expansion occurred predominately in the centromeric and pericentromeric regions of B genome chromosomes accompanied by little expansion and elimination on other chromosomes. This result indicated that the B genome might be more sensitive to the "genome shock" and more changeable during wheat polyplodization. CONCLUSIONS: During the bread wheat evolution, SSRs including (AAC)n, (AAG)n, (AGC)n and (AG)n in B genome displayed the greatest changes (sequence expansion) especially in centromeric and pericentromeric regions during the polyploidization from Ae. speltoides S genome, the most likely donor of B genome. This work would enable a better understanding of the wheat genome formation and evolution and reinforce the viewpoint that B genome was originated from S genome.
BACKGROUND: During the bread wheat speciation by polyploidization, a series of genome rearrangement and sequence recombination occurred. Simple sequence repeat (SSR) sequences, predominately located in heterochromatic regions of chromosomes, are the effective marker for tracing the genomic DNA sequence variations. However, to date the distribution dynamics of SSRs on chromosomes of bread wheat and its donors, including diploid and tetraploid Triticum urartu, Aegilops speltoides, Aegilops tauschii, Triticum turgidum ssp. dicocoides, reflecting the genome evolution events during bread wheat formation had not been comprehensively investigated. RESULTS: The genome evolution was studied by comprehensively comparing the distribution patterns of (AAC)n, (AAG)n, (AGC)n and (AG)n in bread wheatTriticum aestivum var. Chinese Spring and its progenitors T. urartu, A. speltoides, Ae. tauschii, wild tetroploid emmer wheat T. dicocoides, and cultivated emmer wheatT. dicoccum. Results indicated that there are specific distribution patterns in different chromosomes from different species for each SSRs. They provided efficient visible markers for identification of some individual chromosomes and SSR sequence evolution tracing from the diploid progenitors to hexaploid wheat. During wheat speciation, the SSR sequence expansion occurred predominately in the centromeric and pericentromeric regions of B genome chromosomes accompanied by little expansion and elimination on other chromosomes. This result indicated that the B genome might be more sensitive to the "genome shock" and more changeable during wheat polyplodization. CONCLUSIONS: During the bread wheat evolution, SSRs including (AAC)n, (AAG)n, (AGC)n and (AG)n in B genome displayed the greatest changes (sequence expansion) especially in centromeric and pericentromeric regions during the polyploidization from Ae. speltoides S genome, the most likely donor of B genome. This work would enable a better understanding of the wheat genome formation and evolution and reinforce the viewpoint that B genome was originated from S genome.
Authors: Zhiyun Gong; Yufeng Wu; Andrea Koblízková; Giovana A Torres; Kai Wang; Marina Iovene; Pavel Neumann; Wenli Zhang; Petr Novák; C Robin Buell; Jirí Macas; Jiming Jiang Journal: Plant Cell Date: 2012-09-11 Impact factor: 11.277