| With the global warming and decline in soil quatity, plants often suffer from various abiotic stresses during the growth and development. These abiotic stresses ultimately play a role through metablic disturbance of water, ions, and reactive oxygen species. In addition to the above several typical metabolites, Methylglyoxal(MG), on behalf of keto-aldehydes, is a toxic metabolite. Modification of proteins, lipids and DNA by MG result in change of their structure and function. This eventually lead to cell damage and death. To alleviate the damage caused by MG on the plant growth and development, plants have developed complex degradation mechanism. The glyoxalase system is the main pathway. MG was converted to lactate upon this system to regulate plant growth and development, the stress tolerance of plants can be improved.In this study, the glyoxalase genes were screened from the maize genome by bioinformatic methods. Structure, evolutionary relationships, gene expression patterns of various members of three glyoxalase gene families were analyzed. Simultaneously, the ZmGLYI-8 gene was isolated from the maize germplasm POB21 by homologue cloning method, and the sequence, expression pattern and biological function of the gene were analyzed systematically. The main results are as follows:(1) Using bioinformatics techniques, 13 glyoxalase I genes(GLYI), 3 glyoxalase II genes(GLYII) and 7 glyoxalaseIII genes(GLYIII) were obtained from the B73 genome. Using Arabidopsis thaliana as a reference genome, we analyzed the homology, genic structure, protein domains and chromosome mapping of glyoxalase genes. The results showed that three kinds of glyoxalase genes belong to different family without evolutionary consistency. Within the same glyoxalase family, evolutionary conservation and asynchronization of gene duplication can be found. There is also a certain species preference in gene duplication of different glyoxalase gene family between Arabidopsis and maize genome.(2) Using genevestigator database and qRT-PCR technology, the expression characteristics of the glyoxalase genes in maize were analyzed and tested. A certain preference of gene expression of three glyoxalse families in different developmental stages suggested the functional difference of these genes. Tissue-specific assay by qRT-PCR method of GLYI and GLYII gene expression indicated that the expression level of all genes in the root is lowest and the expression levels of most genes(9 GLYI genes, 1 GLYII gene) is high in the leaves. Under abiotic stresses of high temperature, drought and high salt as well as the treatment of metabolite MG, H2O2 and hormone abscisic acid(ABA), ET and MeJA, regulatory direction and expression level of most genes presented rich diversity. This result showed that the majority of glyoxalase genes were widely involved in various abiotic stress response and signal transduction pathways.(3) A homologue of glyoxalase gene ZmGLYI-8 in POB21 genome was cloned by homology cloning technique. Sequence analysis revealed that the 1044 bp of full-length CDS encoded a protein of 347 amino acids, the isoelectric point of the protein is 6.49 and the predicted molecular weight is 38223.83 Da. Sequence alignment and phylogenetic analysis demonstrated that this gene is high homology with GRMZM2G076006 in B73 genome. As qRT-PCR analysis indicated, the expression level of ZmGLYI-8 in leaves was significantly higher than that in roots and stems. The gene expression were indced by treatment of PEG, high temperature, MG, ABA and MeJA by different degrees.(4) Using heterogenous overexpression of the ZmGLYI-8 gene, we analyzed the biological function of this gene in Arabidopsis and Escherichia coli.. Results showed that overexpression of the gene could improve the tolerance of the Escherichia coli against high concentration of MG, mannitol and NaCl. Likewise, it also can enhance resistance of Arabidopsis young seedlings and adult plants to drought and high salt. |
PDF Full Text Request