• Aimin Zhang

      Articles written in Journal of Genetics

    • A complete mitochondrial genome of wheat (Triticum aestivum cv. Chinese Yumai), and fast evolving mitochondrial genes in higher plants

      Peng Cui Huitao Liu Qiang Lin Feng Ding Guoyin Zhuo Songnian Hu Dongcheng Liu Wenlong Yang Kehui Zhan Aimin Zhang Jun Yu

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      Plant mitochondrial genomes, encoding necessary proteins involved in the system of energy production, play an important role in the development and reproduction of the plant. They occupy a specific evolutionary pattern relative to their nuclear counterparts. Here, we determined the winter wheat (Triticum aestivum cv. Chinese Yumai) mitochondrial genome in a length of 452 and 526 bp by shotgun sequencing its BAC library. It contains 202 genes, including 35 known protein-coding genes, three rRNA and 17 tRNA genes, as well as 149 open reading frames (ORFs; greater than 300 bp in length). The sequence is almost identical to the previously reported sequence of the spring wheat (T. aestivum cv. Chinese Spring); we only identified seven SNPs (three transitions and four transversions) and 10 indels (insertions and deletions) between the two independently acquired sequences, and all variations were found in non-coding regions. This result confirmed the accuracy of the previously reported mitochondrial sequence of the Chinese Spring wheat. The nucleotide frequency and codon usage of wheat are common among the lineage of higher plant with a high AT-content of 58%. Molecular evolutionary analysis demonstrated that plant mitochondrial genomes evolved at different rates, which may correlate with substantial variations in metabolic rate and generation time among plant lineages. In addition, through the estimation of the ratio of non-synonymous to synonymous substitution rates between orthologous mitochondrion-encoded genes of higher plants, we found an accelerated evolutionary rate that seems to be the result of relaxed selection.

    • Distribution of genes associated with yield potential and water-saving in Chinese Zone II wheat detected by developed functional markers

      Zhenxian Gao Zhanliang Shi Aimin Zhang Jinkao Guo

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      Functional markers (FMs) developed from sequence polymorphisms are present in allelic variants of a functional gene at a locus and are directly associated with phenotypic variations. In this study, FM linked to Rht-B1, Rht-D1, TaCwi-A1, TaSus2-2B, TaGW2-6A and Dreb-B1 genes conferring to yield potential and water-saving were selected to analyse the distribution in 102 wheat varieties, most of which were authorized in the past decade and adapted to grow in Zone II of China. First, the semi-dwarfing genes Rht-B1b and Rht-D1b (mutant alleles) conferring to grain yield were analysed. The frequencies of favourable alleles Rht-B1b and Rht-D1b were 32.4 and 58.8%, respectively. Comparing with the previous report, the frequency of Rht-B1b among cultivars in this study is similar to the frequency among cultivars released in the 1990s, while the frequency of Rht-D1b is slightly lower than the previous report 63.9%. Twelve (11.8%) cultivars neither contained Rht-B1b nor Rht-D1b, while only Yumai 66 contained both semidwarfing genes. Linyuan8 and Xinong 928 are heterozygous at RhtB1 locus and Zhengmai 9023 is heterozygous at both RhtB1 and Rht-D1 loci. Second, the TaCwi-A1, TaSus2-2B and TaGW2-6A genes considered as candidate genes related to grain weight were detected. We found that the frequencies of the favourable alleles were 76.5, 56.9 and 69.6%, respectively. Among the 102 wheat varieties, 30 contained all the three favourable genes, 45 contained two of the three favourable genes and 27 contained only one. There are eight wheat varieties (7.8%) in hybrid state at the TaCWI-A1 locus. Third, the designed FM linked to water-saving gene Dreb-B1 were validated on 102 wheat varieties. The results showed that the haplotypes of 47 wheat varieties at the Dreb-B1 locus were same as that of Opata 85, and 55 wheat varieties showed the signal expected for W7984 (Opata 85 and W7984 are parents of the ITMI mapping population). This information will be useful for the wheat breeding programmes aiming at improving yield and water use efficiency in Shijiazhuang located in China Zone II.

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