Showing papers by "Guangmin Xia published in 2007"

Arabidopsis DREB1A / CBF3 bestowed transgenic tall fescue increased tolerance to drought stress

Abstract: In order to improve drought tolerance of tall fescue (Festuca arundinacea Schreb.), an important perennial cool-season grass, we introduced Arabidopsis DREB1A/CBF3 driven by the inducible rd29A promoter into tall fescue mediated by Agrobacterium tumefaciens strains AGL1. PCR and Southern blot analysis confirmed that DREB1A/CBF3 gene had been integrated into the genome of tall fescue. AtDREB1A gene was stably inherited and expressed in T1 plants, as indicated by PCR, RT-PCR and Western blotting analysis. The transgenic plants also showed an increased expression of AtP5CS2, which was confirmed to be a downstream target gene of DREB in Arabidopsis. We found that the transgenic tall fescue showed increased resistance to drought and accumulated high level of proline, indicating ability of the CBF3 gene to induce stress related response in tall fescue. The result here provides evidence for drought improvement of tall fescue via transformation with stress-related transcription factor and stress-induced promoter.

Generation of novel high quality HMW-GS genes in two introgression lines of Triticum aestivum/Agropyron elongatum.

Abstract: Background High molecular weight glutenin subunits (HMW-GS) have been proved to be mostly correlated with the processing quality of common wheat (Triticum aestivum). But wheat cultivars have limited number of high quality HMW-GS. However, novel HMW-GS were found to be present in many wheat asymmetric somatic hybrid introgression lines of common wheat/Agropyron elongatum.

Genotyping of somatic hybrids between Festuca arundinacea Schreb. and Triticum aestivum L.

Abstract: In order to genotype hybrid genomes of distant asymmetric somatic hybrids, we synthesized hybrid calli and plants via PEG-mediated protoplast fusion between recipient tall fescue (Festuca. arundinacea Schreb.) and donor wheat (Triticum aestivum L.). Seventeen and 25 putative hybrid clones were produced from the fusion combinations I and II, each with the donor wheat protoplast treated by UV light for 30 s and 1 min, respectively. Isozyme and RAPD profiles confirmed that ten hybrid clones were obtained from combination I and 19 from combination II. Out of the 29 hybrids, 12 regenerated hybrid plants with tall fescue phenotype. Composition and methylation-variation of the nuclear and cytoplasmic genomes of some hybrids, either with or without regenerative ability, were compared by genomic in situ hybridization, restriction fragment length polymorphism, and DNA methylation-sensitive amplification polymorphism. Our results indicated that these selected hybrids all contained introgressed nuclear and cytoplasmic DNA as well as obvious methylation variations compared to both parents. However, there were no differences either in nuclear/cytoplasmic DNA or methylation degree between the regenerable and non-regenerable hybrid clones. We conclude that both regeneration complementation and genetic material balance are crucial for hybrid plant regeneration.

Analysis of remote asymmetric somatic hybrids between common wheat and Arabidopsis thaliana

Abstract: Callus-derived protoplasts of common wheat (Triticum aestivum L. cv. Hesheng 3) irradiated with ultraviolet light were fused by using the PEG method with cell suspension-derived protoplasts of Arabidopsis thaliana. Regenerated calli and green plants resembling that of wheat were obtained. The hybrid nature of putative calli and plants were confirmed by isozyme, random amplified polymorphic DNA and genomic in situ hybridization (GISH) analyses. GISH results indicated that 1∼3 small chromosome fragments of A. thaliana were found introgression into the terminals of wheat chromosomes, forming highly asymmetric hybrids. Cytoplasmic genome tests did not show any cytoplasmic genetic materials from A. thaliana. However, variations from the normal wheat cytoplasmic genome were found, indicating recombination or rearrangement occurred during the process of somatic hybridization. The chromosome elimination in the asymmetric somatic hybridization of remote phylogenetic relationship was discussed. A miniature inverted-repeat transposable element related sequence was found by chance in the hybrids which might accompany and impact the process of somatic hybridization.

Variation and potential value in wheat breeding of low-molecular-weight glutenin subunit genes cloned by genomic and RT-PCR in a derivative of somatic introgression between common wheat and Agropyron elongatum

Abstract: In order to exploit the composition, origination and possible relationship with quality, 26 low-molecular-weight glutenin subunit (LMW-GS) open reading frames (ORFs) were cloned and sequenced from a derivative of an asymmetric somatic hybrid between wheat and Agropyron elongatum and parent wheat. Most of these (23) were of LMW-m type. One sequence derived from the selected derivative has a unique N-terminal peptide sequence NGRLDASL. Most of the deduced peptide sequences have eight Cys residues, but two have nine and two others ten. Reverse transcriptase polymerase chain reaction (RT-PCR) results show the LMW-GS genes that can express in the endosperm of the derivative. Lmwgh-15 from the derivative has four extra deduced Cys residues and comprises 14.6% of the total expression sequences, which may play an important role in wheat flour quality. A phylogenetic analysis, based on both deoxyribonucleic acid (DNA) and peptide sequences, indicated that most of derivative’s LMW-GS genes were inherited from the receptor wheat, but a few could be traced to the donor A. elongatum. There was evidence for both chimerism and mutation in a number of the derivative’s LMW-GS genes. We conclude that somatic hybridization is able not only to introduce alien genes but also to generate novel LMW-GS alleles.