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91.
TILLING to detect induced mutations in soybean 总被引:2,自引:0,他引:2
Jennifer L Cooper Bradley J Till Robert G Laport Margaret C Darlow Justin M Kleffner Aziz Jamai Tarik El-Mellouki Shiming Liu Rae Ritchie Niels Nielsen Kristin D Bilyeu Khalid Meksem Luca Comai Steven Henikoff 《BMC plant biology》2008,8(1):1-10
Background
Potato is a staple food in the diet of the world's population and also being used as animal feed. Compared to other crops, however, potato tubers are relatively poor in the essential amino acid, methionine. Our aim was to increase the methionine content of tubers by co-expressing a gene involved in methionine synthesis with a gene encoding a methionine-rich storage protein in potato plants.Results
In higher plants, cystathionine γ-synthase (CgS) is the first enzyme specific to methionine biosynthesis. We attempted to increase the methionine content of tubers by expressing the deleted form of theArabidopsis CgS (CgS Δ90), which is not regulated by methionine, in potato plants. To increase the incorporation of free methionine into a storage protein theCgS Δ90was co-transformed with the methionine-rich15-kD β-zein. Results demonstrated a 2- to 6-fold increase in the free methionine content and in the methionine content of the zein-containing protein fraction of the transgenic tubers. In addition, in line with higher methionine content, the amounts of soluble isoleucine and serine were also increased. However, all of the lines with high level of CgSΔ90 expression were phenotypically abnormal showing severe growth retardation, changes in leaf architecture and 40- to 60% reduction in tuber yield. Furthermore, the colour of the transgenic tubers was altered due to the reduced amounts of anthocyanin pigments. The mRNA levels of phenylalanine ammonia-lyase (PAL), the enzyme catalysing the first step of anthocyanin synthesis, were decreased.Conclusion
Ectopic expression of CgSΔ90 increases the methionine content of tubers, however, results in phenotypic aberrations in potato. Co-expression of the 15-kD β-zein with CgSΔ90 results in elevation of protein-bound methionine content of tubers, but can not overcome the phenotypical changes caused by CgSΔ90 and can not significantly improve the nutritional value of tubers. The level ofPAL mRNA and consequently the amount of anthocyanin pigments are reduced in the CgSΔ90 transgenic tubers suggesting that methionine synthesis and production of anthocyanins is linked. 相似文献92.
Background
Several techniques are available to study gene function, but many are less than ideal for soybean. Reverse genetics, a relatively new approach, can be utilized to identify novel mutations in candidate genes; this technique has not produced an allelic variant with a confirmed phenotype in soybean. Soybean raffinose synthase genes and microsomal omega-6 fatty acid desaturase genes were screened for novel alleles in mutagenized soybean populations. 相似文献93.
Background
In microarray data analysis, factors such as data quality, biological variation, and the increasingly multi-layered nature of more complex biological systems complicates the modelling of regulatory networks that can represent and capture the interactions among genes. We believe that the use of multiple datasets derived from related biological systems leads to more robust models. Therefore, we developed a novel framework for modelling regulatory networks that involves training and evaluation on independent datasets. Our approach includes the following steps: (1) ordering the datasets based on their level of noise and informativeness; (2) selection of a Bayesian classifier with an appropriate level of complexity by evaluation of predictive performance on independent data sets; (3) comparing the different gene selections and the influence of increasing the model complexity; (4) functional analysis of the informative genes. 相似文献94.
Flores T Karpova O Su X Zeng P Bilyeu K Sleper DA Nguyen HT Zhang ZJ 《Transgenic research》2008,17(5):839-850
RNA interference (RNAi) has been recently employed as an effective experimental tool for both basic and applied biological studies in various organisms including plants. RNAi deploys small RNAs, mainly small interfering RNAs (siRNAs), to mediate the degradation of mRNA for regulating gene expression in plants. Here we report an efficient siRNA-mediated gene silencing of the omega-3 fatty acid desaturase (FAD3) gene family in a complex genome, the soybean (Glycine max). The FAD3 enzyme is responsible for the synthesis of alpha-linolenic acids (18:3) in the polyunsaturated fatty acid pathway. It is this fatty acid that contributes mostly to the instability of soybean and other seed oils. Therefore, a significant reduction of this fatty acid will increase the stability of the seed oil, enhancing the seed agronomical value. A conserved nucleotide sequence, 318-nt in length, common to the three gene family members was used as an inverted repeat for RNA interference. The RNAi expression cassette was driven by a seed-specific promoter. We show that the transgene-produced siRNA caused silencing of FAD3 that was comparable to the fad3 mutant phenotype and, furthermore, that such a silencing is stably inherited in engineered soybean lines. Since the pool size of the alpha-linolenic acids is small relative to the other polyunsaturated fatty acids in soybean, the significant reduction of this fatty acid suggests a role and great potential for the siRNA strategy in silencing gene families in a complex genome. 相似文献
95.
Pham AT Lee JD Shannon JG Bilyeu KD 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2011,123(5):793-802
The alteration of fatty acid profiles in soybean to improve soybean oil quality has been a long-time goal of soybean researchers.
Soybean oil with elevated oleic acid is desirable because this monounsaturated fatty acid improves the nutrition and oxidative
stability of soybean oil compared to other oils. In the lipid biosynthetic pathway, the enzyme fatty acid desaturase 2 (FAD2)
is responsible for the conversion of oleic acid precursors to linoleic acid precursors in developing soybean seeds. Two genes
encoding FAD2-1A and FAD2-1B were identified to be expressed specifically in seeds during embryogenesis and have been considered
to hold an important role in controlling the seed oleic acid content. A total of 22 soybean plant introduction (PI) lines
identified to have an elevated oleic acid content were characterized for sequence mutations in the FAD 2-1A and FAD2-1B genes. PI 603452 was found to contain a deletion of a nucleotide in the second exon of FAD2-1A. These important SNPs were used in developing molecular marker genotyping assays. The assays appear to be a reliable and
accurate tool to identify the FAD 2-1A and FAD2-1B genotype of wild-type and mutant plants. PI 603452 was subsequently crossed with PI 283327, a soybean line that has a mutation
in FAD2-1B. Interestingly, soybean lines carrying both homozygous insertion/deletion mutation (indel) FAD2-1A alleles and mutant FAD2-1B alleles have an average of 82–86% oleic acid content, compared to 20% in conventional soybean, and low levels of linoleic
and linolenic acids. The newly identified indel mutation in the FAD2-1A gene offers a simple method for the development of high oleic acid commercial soybean varieties. 相似文献
96.
Comparison of the effects of concentration, pH and anion species on astringency and sourness of organic acids 总被引:3,自引:1,他引:3
The separate effects of concentration, pH and anion species on intensity of
sourness and astringency of organic acids were evaluated. Judges rated
sourness and astringency intensity of lactic, malic, tartaric and citric
acid solutions at three levels of constant pH varying in normality and at
three levels of constant concentration varying in pH. To assess the
comparative sourness and astringency of the organic acid anions of study,
binary acid solutions matched in pH and titratable acidity were also rated.
As pH was decreased in equinormal solutions, both sourness and astringency
increased significantly (P < 0.001). By contrast, as the normality of
the equi-pH solutions was increased, only sourness demonstrated significant
increases (P < 0.001) while astringency remained constant or decreased
slightly. At the lowest normality tested, all solutions were more
astringent than sour (P < 0.05). Although lactic acid was found to be
significantly more sour than citric acid (P < 0.05), no other sourness
or astringency differences among the organic acid anions were noted. This
study demonstrates for the first time that astringency elicited by acids is
a function of pH and not concentration or anion species, and confirms that
sourness is independently influenced by concentration, pH and anion species
of the acid.
相似文献
97.
Background
The rapid and accurate identification of species is a critical component of large-scale biodiversity monitoring programs. DNA arrays (micro and macro) and DNA barcodes are two molecular approaches that have recently garnered much attention. Here, we compare these two platforms for identification of an important group, the mammals. 相似文献98.
Igor Y Oshkin David AC Beck Andrew E Lamb Veronika Tchesnokova Gabrielle Benuska Tami L McTaggart Marina G Kalyuzhnaya Svetlana N Dedysh Mary E Lidstrom Ludmila Chistoserdova 《The ISME journal》2015,9(5):1119-1129
We report observations on the dynamics of bacterial communities in response to methane stimulus in laboratory microcosm incubations prepared with lake sediment samples. We first measured taxonomic compositions of long-term enrichment cultures and determined that, although dominated by Methylococcaceae types, these cultures also contained accompanying types belonging to a limited number of bacterial taxa, methylotrophs and non-methylotrophs. We then followed the short-term community dynamics, in two oxygen tension regimens (150 μM and 15 μM), observing rapid loss of species diversity. In all microcosms, a single type of Methylobacter represented the major methane-oxidizing partner. The accompanying members of the communities revealed different trajectories in response to different oxygen tensions, with Methylotenera species being the early responders to methane stimulus under both conditions. The communities in both conditions were convergent in terms of their assemblage, suggesting selection for specific taxa. Our results support prior observations from metagenomics on distribution of carbon from methane among diverse bacterial populations and further suggest that communities are likely responsible for methane cycling, rather than a single type of microbe. 相似文献
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