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Articles by Ya-Xi Liu
Total Records ( 7 ) for Ya-Xi Liu
  Li-Juan Yang , Ya-Xi Liu , Bi-Ling Xu , Wei Li and Guo-Yue Chen
  One hundred and thirteen low-molecular-weight glutenin subunits encoding sequences and parts of upstream were characterized from Triticum dicoccoides. The encoded proteins of 113 genes had similar structures to previously characterized LMW-GS. These sequences had 856~1402 nucleotides in length with 2~26 repeat motifs. Most of the sequences were typical LMW-m glutenin subunits genes and the frequency of SNPs was 1.6 out of 10 bases and A-G mutation was the most frequent. Fourteen deduced amino acid sequences were found to be possessed with an additional cysteine residue in C-ter I. Thirty-six haplotypes were detected and phylogenetic analysis indicated that the 36 haplotypes could be classified into 3 haplotype groups. Individually classifications based on the four main domains of LMW-GS DNA sequences, 5’flanking, single peptide, N-terminals and C-terminal, were in agreement with the classification based on the coding regions. Consilient evolution was found between domains of LMW-GS as well as each domain and the whole coding region. The results revealed the important information of low-molecular-weight glutenin subunit gene family and contributed to our understanding of functional aspects of the low-molecular-weight glutenin subunit genes.
  Wei Li , An-Jun Liu , Yu-Zhen Sheng , Guo-Yue Cheng , Zi-En Pu and Ya-Xi Liu
  In order to exploiting new genetic resources for the wheat breeding, nine waxy genes (granule-bound starch synthase, GBSSI) were obtained from wild species, Aegilops tauschii (DD) by special primer PCR cloning. These sequences showed the higher similarity to the sequences of Wx-D1 locus in common wheat. The analysis of variation and alignment of sequences showed that all the sequences could be distinguished, although from the same species. Out of 35 variable sites of nucleotide in the whole sequences, twelve variable sites located on the region of exon and made six amino acid residues change. Most of variable sites located on transit peptide. Using neighbour-joining method, phylogenetic tree suggested that the sequences of waxy gene from Ae. tauschii were clustered closely with the sequences of Wx-D1 locus and far with the sequence of Wx-A1 and Waxy-B1 loci in Triticum L.. Moreover, Ae. tauschii showed more close relationship with Triticum L. and barley and had more close relationship with barley and far distance with rice, potato, pea and Arabidopsis. These results would contribute to the deep understanding of functional aspects and evolution of waxy gene and the improving of starch quality in common wheat.
  Wei Li , An-Jun Liu , Yu-Zhen Sheng , Zi-En Pu , Ya-Xi Liu and Guo-Yue Cheng
  In order to knowing the variation of starch synthase I (SSI) in Triticum L. and Aegilops and exploiting new gene resources for the improving of starch quality in common wheat, using PCR cloning, eight sequences of SSI genes were obtained from AS60 (DD, Aegilops tauschii), AS2255 (AABB, Triticum turgidum), SHW-L1 (AABBDD, synthetic hexaploid wheat) and Chuanmai 32 (AABBDD, Triticum aestivum), respectively. These sequences of SSI gene showed the higher conservative characterization between different materials. A total of 10 variable nucleotide bases and two substitutions of amino acid residues (Ser/Asn and Ala/Val) were observed in the cloning sequences. Alignment of all sequences, including SSI gene from T. aestivum, Hordeum vulgare, Brachypodium distachyon, Zea mays and Oryza sativa suggested that the sequences from Ae, tauschii, T. turgidum and synthetic hexaploid wheat, were more similar to SSI gene from common wheat and barley and far distance with sequences from Brachypodium distachyon, Zea mays and Oryza sativa. Using neighbor-joining method, phylogenetic tree including a total of 28 sequences could be clustered into four groups. Most of sequences of SSI from different species were clustered together and SSI gene showed the clear difference with other starch synthases, including Granule-bound Starch Synthase (GBSS), SSII, SSIII and SSIV. These results suggested that there was variation fro SSI gene in Triticum L. and Aegilops. It necessary to developing molecular markers for exploit genetic resources and the improving of wheat starch quality.
  Ya-Xi Liu , Wei Li , Yu-Ming Wei , Guo-Yue Chen and You-Liang Zheng
  This study characterizes 15 waxy genes from 15 accessions of the einkorn wheats Triticum urartu, T. boeoticum and T. monococcum. The mature protein coding sequences of waxy genes were analyzed. Nucleotide sequence variations in these regions resulted from base substitution and/or indel mutations. This work identified 8 distinct haplotypes from the diploid wheat waxy gene sequences. A main haplotype was found in 7 gene samples from the Au genome and Am genome. The waxy gene sequences from the Au and Am genomes could be obviously clustered into two clades, but the sequences from the Am genome of T. boeoticum and T. monococcum could not be clearly distinguished. The phylogenetic analysis revealed that the waxy gene sequences from the Am genome had accumulated fewer variations and evolved at a slower rate than the sequences from the Au genome. These results would contribute to the understanding of functional aspects and efficient utilization of waxy genes.
  Ya-Xi Liu , Xiao-Huan Sun , Bi-Ling Xu and Guo-Yue Chen
  Plant architecture is governed by the action of meristems. During vegetative development, the shoot apical meristem is responsible for initiating all of the above-ground structures including the nodes, internodes, leaves, axillary meristems and the inflorescence. Five barley mutants with low-tiller have been found, currently including, low number of tillers1 (lnt1.a), absent lower laterals1 (als1), intermedium-b (int-b), uniculm2 (cul2.b), uniculm4 (cul4) and semi brachytic (uzu). Specifically, the cul2.b mutant failed to develop tillers, while the lnt1.a mutant can produce 1-4 tillers. Genetic analysis indicated that two mutant phenotypes were caused by two recessive genes cul2.b and lnt1.a, respectively. In this study, two F2 populations, 279 individuals derived from BowmanxGSHO 531 and 184 individuals derived from BowmanxGSHO 1984 were developed for mapping the cul2.b and lnt1.a genes using Simple Sequence Repeats (SSR) markers. F3 populations were created to identify genotypes of F2 individuals. Ultimately, cul2.b was located between SSR markers GBM1212 and Bmag 0613 on the long arm of chromosome 6H, with distances of 12.7 and 13.2 cm to the two markers, respectively. Another five SSR markers (GBM 1319, GBM 1423, Bmag 0807, Bmag 0378 and Bmag 0003) on chromosome 6H were also found around the cul2 gene, with distances of 19.6, 33.3, 34.1, 71.5 and 80 cm to the cul2.b gene. The lnt1.a gene was positioned 7.8 cm away from GBM 1043 on chromosome 3H. This study narrowed the block of tiller development gene in the cul2 and lnt1 mutant. It is a benefit for further map-based clone of the genes.
  Ze-Hou Liu , Yong Zhou , Jia Li , Yu-Jiao Liu and Ya-Xi Liu
  Alpha-amylase enzyme is the important member in physiological metabolism of high plant, especially during seed germination stage. The current study identified 19 amy1 genes from 19 hexaploid wheat (Triticum aestivum L.) accessions. The nucleotide and deduced amino acid sequences of amy1 genes were analyzed in detail, respectively. It showed that two main variation types were characterized due to the base substitution and/or indel mutations in genomic nucleotide sequences and the exon and intron domains were presented different variation degree. This study identified 8 clustered haplotypes from hexaploid wheat accessions through characterization of exon domains. The haplotype 8 was the major variation types and the others were low relative frequency. The haplotype 7 was a special kind of haplotypes among amy1 genes in wheat accession PI243793 because of the variation of amino acid sequences at 155-161 sites. These results would contribute to the understanding in functional aspects and efficient utilization of amy1 genes in hexaploid wheat cultivars.
  Wei Li , An-Jun Liu , Yu-Zhen Sheng , Guo-Yue Cheng , Zi-En Pu , Ya-Xi Liu and Li Kong
  In order to exploit new genetic resources for the improving of starch quality of common wheat, the genetic diversity of null alleles of Granule-bound starch synthase I (waxy gene) was investigated by special PCR molecular markers in Triticum L. The results indicated that there was relative abundant genetic diversity of waxy alleles in all accessions. Accession AS2347, AS2356, AS2317 and AS2308 with null allele at Waxy-B1 locus and AS2310 and AS2335 with null alleles at Waxy-A1 and Waxy-B1, were observed in 81 landraces of Triticum turdigum L. from China. In 53 landraces of Triticum aestivum L. from Sichuan, China, eight accessions at Waxy-A1, Waxy-B1 and Waxy-D1 loci and accession AS1668 at Waxy-D1, were observed null alleles. In 29 Triticum macha, Accession PI361862 and PI572911 at three Waxy loci, PI572913 at Waxy-B1 and Waxy-D1, PI572910 at Waxy-A1 and Waxy-D1, PI 290507 at Waxy-B1 and PI572906 at Waxy-D1, respectively, were observed null alleles. Seven accessions with null alleles at Waxy-B1 locus was observed in 28 Triticum sphaerococcum. Specially, the accessions of two regions, Anyue in Sichuan, China and Georgia, had the high frequency of the mutations with null alleles of waxy gene. Landraces of Triticum aestivum L. with the high frequency of waxy wheat, could be considered as a unique genetic resource for improving of waxy wheat. These result suggested that the special molecular marker could be used reliably in evaluation of genetic resources and these mutations also could be directly used in the improving of common wheat.
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