• Lingxia Zhao

      Articles written in Journal of Biosciences

    • Isolation and characterization of a new mannose-binding lectin gene fromTaxus media

      Guoyin Kai Lingxia Zhao Jingui Zheng Lei Zhang Zhiqi Miao Xiaofen Sun Kexuan Tang

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      In this paper, we report the cloning and characterization of the first mannose-binding lectin gene from a gymnosperm plant species,Taxus media. The full-length cDNA ofT. media agglutinin (TMA) consisted of 676 bp and contained a 432 bp open reading frame (ORF) encoding a 144 amino acid protein. Comparative analysis showed that TMA had high homology with many previously reported plant mannose-binding lectins and thattma encoded a precursor lectin with a 26-aa signal peptide. Molecular modelling revealed that TMA was a new mannosebinding lectin with three typical mannose-binding boxes like lectins from species of angiosperms. Tissue expression pattern analyses revealed thattma is expressed in a tissue-specific manner in leaves and stems, but not in fruits and roots. Phylogenetic tree analyses showed that TMA belonged to the structurally and evolutionarily closely related monocot mannose-binding lectin superfamily. This study provides useful information to understand the molecular evolution of plant lectins.

    • Transgenic tobacco plants expressingBoRS1 gene fromBrassica oleracea var.acephala show enhanced tolerance to water stress

      Dongqin Tang Hongmei Qian Lingxia Zhao Danfeng Huang Kexuan Tang

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      Water stress is by far the leading environmental stress limiting crop yields worldwide. Genetic engineering techniques hold great promise for developing crop cultivars with high tolerance to water stress. In this study, theBrassica oleracea var.acephala BoRS1 gene was transferred into tobacco throughAgrobacterium- mediated leaf disc transformation. The transgenic status and transgene expression of the transgenic plants was confirmed by polymerase chain reaction (PCR) analysis, Southern hybridization and semi-quantitative one step RT-PCR analysis respectively. Subsequently, the growth status under water stress, and physiological responses to water stress of transgenic tobacco were studied. The results showed that the transgenic plants exhibited better growth status under water stress condition compared to the untransformed control plants. In physiological assessment of water tolerance, transgenic plants showed more dry matter accumulation and maintained significantly higher levels of leaf chlorophyll content along with increasing levels of water stress than the untransformed control plants. This study shows thatBoRS1 is a candidate gene in the engineering of crops for enhanced water stress tolerance.

    • Molecular evolution of the E8 promoter in tomato and some of its relative wild species

      Lingxia Zhao Liya Lu Lida Zhang Aoxue Wang Ning Wang Zhuobin Liang Xiaowen Lu Kexuan Tang

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      The E8 gene is related to ethylene biosynthesis in plants. To explore the effect of the expression pattern of the E8 gene on different E8 promoters, the molecular evolution of E8 promoters was investigated. A total of 16 E8 promoters were cloned from 16 accessions of seven tomato species, and were further analysed. The results from 19 E8 promoters including three previously cloned E8 promoters (X13437, DQ317599 and AF515784) showed that the size of the E8 promoters varied from 2101 bp (LA2150) to 2256 bp (LA2192); their sequences shared 69.9% homology and the average A/T content was 74.9%. Slide-window analysis divided E8 promoters into three regions – A, B and C – and the sequence identity in these regions was 72.5%, 41.2% and 70.8%, respectively. By searching the cis-elements of E8 promoters in the PLACE database, mutant nucleotides were found in some functional elements, and deletions or insertions were also found in regions responsible for ethylene biosysnthesis (–1702 to –1274) and the negative effect region (–1253 to –936). Our results indicate that the size of the functional region for ethylene biosynthesis in the E8 promoter could be shortened from 429 bp to 113 bp (–1612 to –1500). The results of molecular evolution analysis showed that the 19 E8 promoters could be classified into four clade groups, which is basically consistent with evolution of the tomato genome. Southern blot analysis results showed that the copy number of E8 promoters in tomato and some other wild species changed from 1 to 4. Taken together, our study provides important information for further elucidating the E8 gene expression pattern in tomato, analysing functional elements in the E8 promoter and reconstructing the potent E8 promoter.

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