| Mongolian wheatgrass is an important genetic resource for improving forge grass and crops resistances which is excellent forage grass with many superior characteristics, such as Drought Resistance, Cold Resistance, Disease and Insect Resistance, Tolerance to Saline and Barren in Desert Grassland and Typical Grassland of China. Meanwhile, it is a precious diploid species with genetic and feeding value, ecological value and breeding value in Agropyron Gaertn. There are abundant germplasm resources of Mongolian wheatgrass in China. Discovering and cloning genes related to stress-tolerance are the foundation for improving the stress tolerance in crops with genetic modification, which also plays a crucial role in protecting, innovating germplasm resources and understanding the genetic mechanism of drought tolerance in Mongolian wheatgrass. In this research, Mongolian wheatgrass were used as experimental materials to clone genes related to drought resistance and study mechanism of stress tolerance. The main results are as follows:1. A group 4 of LEA gene, named as MwLEA, was cloned from Mongolian wheatgrass by PCR and 3'and 5'RACE amplification and sequencing, the full length gene of LEA-4 superfamily N-terminal conserved domains was 961 bp, which encodes 171 amino acids. C-terminal of this gene is not conservative.α-helix structure plays a dominant role in the secondary structure ,its expression induced by drought stresses,and it has stronger hydrophilicity of pre-140 amino acids and tail-end decreased.2. A group 3 of LEA gene, named as MwLEA3, was cloned from Mongolia wheatgrass by RT-PCR amplification and sequencing, the full length gene of 8 copies 11-amino acid sequence motif was 1004 bp, including of 3 introns and 3 exons regions ,which encodes 189 amino acids. Ala, Lys and Thr are about 50% of amino acids composition, and no Cys and Trp.α-helix structure plays a dominant role in the secondary structure and has stronger hydrophilicity. This gene is in the form of gene-family in genome by Southern analysis.3. Analysis on expression pattern of MwLEA3 was by RT-PCR. The results revealed that its mRNA level was positively related to the drought tolerance. The gene was also induced by high salt and exogenous ABA treatments. Substantially, the expression of MwLEA3 was higher in roots and stem than that in leaves and their expression patterns were different under different stresses. RNAi expression vector harboring the partial MwLEA3 gene were constructed to study on function of the MwLEA3 gene.4. A partial Actin gene of Mongolian wheatgrass, named as MwACT, was cloned by RT-PCR amplification. MwACT of constitutive expression is housekeeping gene without change with outside factors, which can be used as internal standard when study other genes'expression and regulation in Mongo1ian wheatgrass.5. A partial GSTs gene of Mongolian wheatgrass, named as MwGSTs, was cloned by RT-PCR amplification. The partial gene of GSTs superfamily C-terminal conserved domains. Analysis on the secondary structure and hydrophilicity revealed that it had substrate binding pocket (H- site ) and stronger hydrophobicity.6. 4 genes of Mongo1ian wheatgrass isolated in the research have high homology with wheat, and further illustrate evolution extent of Mongo1ia wheatgrass close to wheat. In theory, support to the View of Mongo1ian wheatgrass being wild relatives of wheat, and it is the optimal species for improving stress-tolerance in wheat was further confirmed.
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